Processes influencing estuarine phytoplankton growth occur over a range of time scales, but many conceptual and numerical models of estuarine phytoplankton production dynamics neglect mechanisms occurring on the shorter (e.g., intratidal) time scales. We used a numerical model to explore the influence of short time-scale variability in phytoplankton sources and sinks on long-term growth in an idealized water column that shallows and deepens with the semidiurnal tide. Model results show that tidal fluctuations in water surface elevation can determine whether long-term phytoplankton growth is positive or negative. Hourly-scale interactions influencing weekly-scale to monthly-scale phytoplankton dynamics include intensification of the depth-averaged benthic grazing effect by water column shallowing and enhancement of water column photosynthesis when solar noon coincides with low tide. Photosynthesis and benthic consumption may modulate over biweekly time scales due to spring-neap fluctuations in tidal range and the 15-d cycle of solar noon-low tide phasing. If tidal range is a large fraction of mean water depth, then tidal shallowing and deepening may significantly influence net phytoplankton growth. In such a case, models or estimates of long-term phytoplankton production dynamics that neglect water surface fluctuations may overestimate or underestimate net growth and could even predict the wrong sign associated with net growth rate.
","language":"English","publisher":"Springer","doi":"10.1007/BF02804885","issn":"01608347","usgsCitation":"Lucas, L., and Cloern, J., 2002, Effects of tidal shallowing and deepening on phytoplankton production dynamics: A modeling study: Estuaries, v. 25, no. 4 A, p. 497-507, https://doi.org/10.1007/BF02804885.","productDescription":"11 p.","startPage":"497","endPage":"507","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true},{"id":552,"text":"San Francisco Bay-Delta","active":false,"usgs":true},{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true},{"id":5079,"text":"Pacific Regional Director's Office","active":true,"usgs":true}],"links":[{"id":233162,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"25","issue":"4 A","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a080de4b0c8380cd51955","contributors":{"authors":[{"text":"Lucas, L.V.","contributorId":62777,"corporation":false,"usgs":true,"family":"Lucas","given":"L.V.","email":"","affiliations":[],"preferred":false,"id":401754,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Cloern, J. E.","contributorId":59453,"corporation":false,"usgs":true,"family":"Cloern","given":"J. E.","affiliations":[],"preferred":false,"id":401753,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70024332,"text":"70024332 - 2002 - Regional seismic wavefield computation on a 3-D heterogeneous Earth model by means of coupled traveling wave synthesis","interactions":[],"lastModifiedDate":"2012-03-12T17:19:59","indexId":"70024332","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3208,"text":"Pure and Applied Geophysics","active":true,"publicationSubtype":{"id":10}},"title":"Regional seismic wavefield computation on a 3-D heterogeneous Earth model by means of coupled traveling wave synthesis","docAbstract":"I present a new algorithm for calculating seismic wave propagation through a three-dimensional heterogeneous medium using the framework of mode coupling theory originally developed to perform very low frequency (f < ???0.01-0.05 Hz) seismic wavefield computation. It is a Greens function approach for multiple scattering within a defined volume and employs a truncated traveling wave basis set using the locked mode approximation. Interactions between incident and scattered wavefields are prescribed by mode coupling theory and account for the coupling among surface waves, body waves, and evanescent waves. The described algorithm is, in principle, applicable to global and regional wave propagation problems, but I focus on higher frequency (typically f ??????0.25 Hz) applications at regional and local distances where the locked mode approximation is best utilized and which involve wavefields strongly shaped by propagation through a highly heterogeneous crust. Synthetic examples are shown for P-SV-wave propagation through a semi-ellipsoidal basin and SH-wave propagation through a fault zone.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Pure and Applied Geophysics","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1007/s00024-002-8725-8","issn":"00334553","usgsCitation":"Pollitz, F., 2002, Regional seismic wavefield computation on a 3-D heterogeneous Earth model by means of coupled traveling wave synthesis: Pure and Applied Geophysics, v. 159, no. 9, p. 2085-2112, https://doi.org/10.1007/s00024-002-8725-8.","startPage":"2085","endPage":"2112","numberOfPages":"28","costCenters":[],"links":[{"id":207192,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s00024-002-8725-8"},{"id":231922,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"159","issue":"9","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"50e4a55be4b0e8fec6cdbe0e","contributors":{"authors":[{"text":"Pollitz, F. F.","contributorId":108280,"corporation":false,"usgs":true,"family":"Pollitz","given":"F. F.","affiliations":[],"preferred":false,"id":400874,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70024443,"text":"70024443 - 2002 - A Brownian model for recurrent earthquakes","interactions":[],"lastModifiedDate":"2012-03-12T17:20:01","indexId":"70024443","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1135,"text":"Bulletin of the Seismological Society of America","onlineIssn":"1943-3573","printIssn":"0037-1106","active":true,"publicationSubtype":{"id":10}},"title":"A Brownian model for recurrent earthquakes","docAbstract":"We construct a probability model for rupture times on a recurrent earthquake source. Adding Brownian perturbations to steady tectonic loading produces a stochastic load-state process. Rupture is assumed to occur when this process reaches a critical-failure threshold. An earthquake relaxes the load state to a characteristic ground level and begins a new failure cycle. The load-state process is a Brownian relaxation oscillator. Intervals between events have a Brownian passage-time distribution that may serve as a temporal model for time-dependent, long-term seismic forecasting. This distribution has the following noteworthy properties: (1) the probability of immediate rerupture is zero; (2) the hazard rate increases steadily from zero at t = 0 to a finite maximum near the mean recurrence time and then decreases asymptotically to a quasi-stationary level, in which the conditional probability of an event becomes time independent; and (3) the quasi-stationary failure rate is greater than, equal to, or less than the mean failure rate because the coefficient of variation is less than, equal to, or greater than 1/???2 ??? 0.707. In addition, the model provides expressions for the hazard rate and probability of rupture on faults for which only a bound can be placed on the time of the last rupture. The Brownian relaxation oscillator provides a connection between observable event times and a formal state variable that reflects the macromechanics of stress and strain accumulation. Analysis of this process reveals that the quasi-stationary distance to failure has a gamma distribution, and residual life has a related exponential distribution. It also enables calculation of \"interaction\" effects due to external perturbations to the state, such as stress-transfer effects from earthquakes outside the target source. The influence of interaction effects on recurrence times is transient and strongly dependent on when in the loading cycle step pertubations occur. Transient effects may be much stronger than would be predicted by the \"clock change\" method and characteristically decay inversely with elapsed time after the perturbation.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Bulletin of the Seismological Society of America","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1785/0120010267","issn":"00371106","usgsCitation":"Matthews, M., Ellsworth, W., and Reasenberg, P., 2002, A Brownian model for recurrent earthquakes: Bulletin of the Seismological Society of America, v. 92, no. 6, p. 2233-2250, https://doi.org/10.1785/0120010267.","startPage":"2233","endPage":"2250","numberOfPages":"18","costCenters":[],"links":[{"id":207088,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1785/0120010267"},{"id":231696,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"92","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e2cbe4b0c8380cd45c5d","contributors":{"authors":[{"text":"Matthews, M.V.","contributorId":70920,"corporation":false,"usgs":true,"family":"Matthews","given":"M.V.","email":"","affiliations":[],"preferred":false,"id":401305,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ellsworth, W.L.","contributorId":48541,"corporation":false,"usgs":true,"family":"Ellsworth","given":"W.L.","email":"","affiliations":[],"preferred":false,"id":401304,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Reasenberg, P.A.","contributorId":19959,"corporation":false,"usgs":true,"family":"Reasenberg","given":"P.A.","email":"","affiliations":[],"preferred":false,"id":401303,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024473,"text":"70024473 - 2002 - Comparison of stomach contents of haddock (Melanogrammus aeglefinus) from the 1981 and 1991 North Sea International Stomach Sampling Projects","interactions":[],"lastModifiedDate":"2012-03-12T17:20:05","indexId":"70024473","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1936,"text":"ICES Journal of Marine Science","active":true,"publicationSubtype":{"id":10}},"title":"Comparison of stomach contents of haddock (Melanogrammus aeglefinus) from the 1981 and 1991 North Sea International Stomach Sampling Projects","docAbstract":"This study analyses data from over 20 000 haddock stomachs collected during the 1981 and 1991 Stomach Sampling Projects of the North Sea. Sampling was within the framework of the Multispecies Virtual Population Analysis (MSVPA) for fisheries stock assessment. In 1981 stomachs were collected to calculate input feeding parameters from main predators. During 1991 the sampling exercise was repeated to test stability of the parameters in the region. We investigate stability of haddock stomach content weight between years accounting for ontogenic, spatial and temporal variations within the scope of the survey resolution. Analysis using generalized linear and additive models is performed for weight of the stomach content including and excluding empty stomachs and also for proportion of stomachs without food. Results indicate that haddock stomach contents varied significantly between years, quarters and North Sea roundfish areas. Content weights were overall higher in 1981 than in 1991. In 1981 levels were high from spring to fall and in 1991 mostly in spring. During both years levels were lowest in the central North Sea and in winter. Most of the deviance in modelling the stomach weight is explained by the length of the predator. Stomachs sampled in 1981 were most frequently empty in spring and those sampled in 1991 in winter. In both years, proportions decreased with fish length except in winter when levels increased. Proportion of empty stomachs was highest in the central region of the North Sea. Most of the proportion variation is explained by quarterly fluctuation. Variation of content weight can be related to prey composition found in the stomachs. High stomach contents are generally associated with high contribution of fish prey to the total stomach content, mainly sandeels. We propose that sandeels were more vulnerable to predation in 1981 than in 1991 due to colder temperatures. ?? 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"ICES Journal of Marine Science","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1006/jmsc.2002.1197","issn":"10543139","usgsCitation":"Adlerstein, S., Temming, A., and Mergardt, N., 2002, Comparison of stomach contents of haddock (Melanogrammus aeglefinus) from the 1981 and 1991 North Sea International Stomach Sampling Projects: ICES Journal of Marine Science, v. 59, no. 3, p. 497-515, https://doi.org/10.1006/jmsc.2002.1197.","startPage":"497","endPage":"515","numberOfPages":"19","costCenters":[],"links":[{"id":207904,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1006/jmsc.2002.1197"},{"id":233191,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"59","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f891e4b0c8380cd4d1b9","contributors":{"authors":[{"text":"Adlerstein, S.A.","contributorId":49960,"corporation":false,"usgs":true,"family":"Adlerstein","given":"S.A.","email":"","affiliations":[],"preferred":false,"id":401405,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Temming, A.","contributorId":84121,"corporation":false,"usgs":true,"family":"Temming","given":"A.","email":"","affiliations":[],"preferred":false,"id":401406,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mergardt, N.","contributorId":9430,"corporation":false,"usgs":true,"family":"Mergardt","given":"N.","email":"","affiliations":[],"preferred":false,"id":401404,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024655,"text":"70024655 - 2002 - The western pond turtle (Clemmys marmorata) in the Mojave River, California, USA: Highly adapted survivor or tenuous relict?","interactions":[],"lastModifiedDate":"2022-08-10T15:24:34.308271","indexId":"70024655","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2515,"text":"Journal of Zoology","active":true,"publicationSubtype":{"id":10}},"displayTitle":"The western pond turtle (Clemmys marmorata) in the Mojave River, California, USA: Highly adapted survivor or tenuous relict?","title":"The western pond turtle (Clemmys marmorata) in the Mojave River, California, USA: Highly adapted survivor or tenuous relict?","docAbstract":"Aspects of the ecology of populations of the western pond turtle Clemmys marmorata were investigated in the Mojave River of the central Mojave Desert, California, U.S.A. One population occupied man-made ponds and the other occurred in natural ponds in the flood plain of the Mojave River. Both habitats are severely degraded as a result of ground water depletion from human activities along the river and one is infested with the exotic shrub saltcedar Tamarix ramosissima. Mean female carapace length (CL) was significantly greater (14.4 cm) than that of males (13.7 cm). Live juveniles were not detected during the period of study. Shelled eggs were visible in X-radiographs from 26 May to 14 July. Mean clutch size was 4.46 and ranged from 3 to 6 eggs. Clutch size did not vary between 1998 and 1999 but was significantly correlated with CL for both years combined, increasing at the rate of 0.548 eggs/cm CL. Gravid female CL ranged from 13.3–16.0 cm. Some females nested in both years. Mean X-ray egg width (21.8 mm) was not significantly correlated with CL or clutch size. X-ray egg width differed more among clutches than within, whether including CL as a co-variate or not. Nesting migrations occurred from 6 June to 8 July with minimum round trip distances ranging from 17.5–585 m with a mean of 195 m. Mean estimated time of departure as measured at the drift fence was 18:13. Most females returned to the ponds in the early morning. Nesting migrations required females to be out of the water for estimated periods of 0.83 to 86 h. The destination of nesting females was typically fluvial sand bars in the channel of the dry riverbed. Overall, the ecology of C. marmorata in the Mojave River is very similar to that reported for populations in less severe habitats along the west coast of the United States. Notable exceptions include long nesting migrations to sandbars in the dry river channel, a possible result of human modifications to the environment, and an apparent lack of terrestrial overwintering behaviour in Mojave River populations. The general similarity of desert and coastal populations is possibly a reflection of their recent geographic separation. Overall, populations in the Mojave River exhibit few obvious adaptations to living in the desert and are considered to be tenuous relicts of the Pleistocene. The small size and tenuous status of these populations suggests that immediate conservation action is needed, including establishment of satellite populations as a hedge against extirpation.
","language":"English","publisher":"Zoological Society of London","doi":"10.1017/S0952836902000584","usgsCitation":"Lovich, J., and Meyer, K., 2002, The western pond turtle (Clemmys marmorata) in the Mojave River, California, USA: Highly adapted survivor or tenuous relict?: Journal of Zoology, v. 256, no. 4, p. 537-545, https://doi.org/10.1017/S0952836902000584.","productDescription":"9 p.","startPage":"537","endPage":"545","numberOfPages":"9","costCenters":[],"links":[{"id":232773,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","otherGeospatial":"Afton Canyon area, Camp Cady Wildlife Area, Mojave River","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -116.4935302734375,\n 34.83071390101431\n ],\n [\n -116.17767333984375,\n 34.83071390101431\n ],\n [\n -116.17767333984375,\n 35.08620310578525\n ],\n [\n -116.4935302734375,\n 35.08620310578525\n ],\n [\n -116.4935302734375,\n 34.83071390101431\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"256","issue":"4","noUsgsAuthors":false,"publicationDate":"2006-02-28","publicationStatus":"PW","scienceBaseUri":"505bb1dae4b08c986b325459","contributors":{"authors":[{"text":"Lovich, J.","contributorId":30944,"corporation":false,"usgs":true,"family":"Lovich","given":"J.","affiliations":[],"preferred":false,"id":402119,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Meyer, K.","contributorId":28204,"corporation":false,"usgs":true,"family":"Meyer","given":"K.","email":"","affiliations":[],"preferred":false,"id":402118,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70024475,"text":"70024475 - 2002 - Porometric properties of siliciclastic marine sand: A comparison of traditional laboratory measurements with image analysis and effective medium modeling","interactions":[],"lastModifiedDate":"2012-03-12T17:20:05","indexId":"70024475","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1941,"text":"IEEE Journal of Oceanic Engineering","active":true,"publicationSubtype":{"id":10}},"title":"Porometric properties of siliciclastic marine sand: A comparison of traditional laboratory measurements with image analysis and effective medium modeling","docAbstract":"During the 1999 sediment acoustics experiment (SAX99), porometric properties were measured and predicted for a well sorted, medium sand using standard laboratory geotechnical methods and image analysis of resin-impregnated sediments. Sediment porosity measured by laboratory water-weight-loss methods (0.372 ?? 0.0073 for mean ??1 standard deviation) is 0.026 lower than determined by microscopic image analysis of resin-impregnated sediments (0.398 ?? 0.029). Values of intrinsic permeability (m2) determined from constant-head permeameter measurements (3.29 ?? 10-11 ?? 0.60 ?? 10-11) and by microscopic image analysis coupled with effective medium theory modeling (2.78 ?? 10-11 ?? 1.01 ?? 10-11) are nearly identical within measurement error. The mean value of tortuosity factor measured from images is 1.49 ?? 0.09, which is in agreement with tortuosity factor determined from electrical resistivity measurements. Slight heterogeneity and anisotropy are apparent in the top three centimeters of sediment as determined by image-based porometric property measurements. However, the overall similarity for both measured and predicted values of porosity and permeability among and within SAX99 sites indicates sediments are primarily homogeneous and isotropic and pore size distributions are fairly uniform. The results indicate that an effective medium theory technique and two-dimensional image analysis accurately predicts bulk permeability in resin-impregnated sands.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"IEEE Journal of Oceanic Engineering","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1109/JOE.2002.1040940","issn":"03649059","usgsCitation":"Reed, A., Briggs, K., and Lavoie, D.L., 2002, Porometric properties of siliciclastic marine sand: A comparison of traditional laboratory measurements with image analysis and effective medium modeling: IEEE Journal of Oceanic Engineering, v. 27, no. 3, p. 581-592, https://doi.org/10.1109/JOE.2002.1040940.","startPage":"581","endPage":"592","numberOfPages":"12","costCenters":[],"links":[{"id":207928,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1109/JOE.2002.1040940"},{"id":233226,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"27","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a7dd8e4b0c8380cd7a1c4","contributors":{"authors":[{"text":"Reed, A.H.","contributorId":94818,"corporation":false,"usgs":true,"family":"Reed","given":"A.H.","email":"","affiliations":[],"preferred":false,"id":401412,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Briggs, K.B.","contributorId":52368,"corporation":false,"usgs":true,"family":"Briggs","given":"K.B.","email":"","affiliations":[],"preferred":false,"id":401411,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Lavoie, D. L.","contributorId":46640,"corporation":false,"usgs":true,"family":"Lavoie","given":"D.","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":401410,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024670,"text":"70024670 - 2002 - U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone","interactions":[],"lastModifiedDate":"2012-03-12T17:20:07","indexId":"70024670","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":835,"text":"Applied Geochemistry","active":true,"publicationSubtype":{"id":10}},"title":"U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone","docAbstract":"Uranium, Th and Pb isotopes were analyzed in layers of opal and chalcedony from individual mm- to cm-thick calcite and silica coatings at Yucca Mountain, Nevada, USA, a site that is being evaluated for a potential high-level nuclear waste repository. These calcite and silica coatings on fractures and in lithophysal cavities in Miocene-age tuffs in the unsaturated zone (UZ) precipitated from descending water and record a long history of percolation through the UZ. Opal and chalcedony have high concentrations of U (10 to 780 ppm) and low concentrations of common Pb as indicated by large values of 206Pb/204Pb (up to 53,806), thus making them suitable for U-Pb age determinations. Interpretations of U-Pb isotope systems in opal samples at Yucca Mountain are complicated by the incorporation of excess 234U at the time of mineral formation, resulting in reverse discordance of U-Pb ages. However, the 207PB/235U ages are much less affected by deviation from initial secular equilibrium and provide reliable ages of most silica deposits between 0.6 and 9.8 Ma. For chalcedony subsamples showing normal age discordance, these ages may represent minimum times of deposition. Typically, 207Pb/235U ages are consistent with the microstratigraphy in the mineral coating samples, such that the youngest ages are for subsamples from outer layers, intermediate ages are from inner layers, and oldest ages are from innermost layers. 234U and 230Th in most silica layers deeper in the coatings are in secular equilibrium with 238U, which is consistent with their old age and closed system behavior during the past -0.5 Ma. The ages for subsamples of silica layers from different microstratigraphic positions in individual calcite and silica coating samples collected from lithophysal cavities in the welded part of the Topopah Spring Tuff yield slow long-term average growth rates of 1 to 5 mm/Ma. These data imply that the deeper parts of the UZ at Yucca Mountain maintained long-term hydrologic stability over the past 10 Ma. despite significant climate variations. U-Pb ages for subsamples of silica layers from different microstratigraphic positions in individual calcite and silica coating samples collected from fractures in the shallower part of the UZ (welded part of the overlying Tiva Canyon Tuff) indicate larger long-term average growth rates up to 23 mm/Ma and an absence of recently deposited materials (ages of outermost layers are 3-5 Ma.). These differences between the characteristics of the coatings for samples from the shallower and deeper parts of the UZ may indicate that the nonwelded tuffs (PTn), located between the welded parts of the Tiva Canyon and Topopah Spring Tuffs, play an important role in moderating UZ flow.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Applied Geochemistry","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/S0883-2927(02)00032-X","issn":"08832927","usgsCitation":"Neymark, L., Amelin, Y., Paces, J., and Peterman, Z.E., 2002, U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone: Applied Geochemistry, v. 17, no. 6, p. 709-734, https://doi.org/10.1016/S0883-2927(02)00032-X.","startPage":"709","endPage":"734","numberOfPages":"26","costCenters":[],"links":[{"id":478726,"rank":10000,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://digital.library.unt.edu/ark:/67531/metadc740548/","text":"External Repository"},{"id":207826,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0883-2927(02)00032-X"},{"id":233061,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"17","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bb9c3e4b08c986b327dba","contributors":{"authors":[{"text":"Neymark, L.A. 0000-0003-4190-0278","orcid":"https://orcid.org/0000-0003-4190-0278","contributorId":56673,"corporation":false,"usgs":true,"family":"Neymark","given":"L.A.","affiliations":[],"preferred":false,"id":402174,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Amelin, Y.","contributorId":62800,"corporation":false,"usgs":true,"family":"Amelin","given":"Y.","affiliations":[],"preferred":false,"id":402175,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Paces, J.B. 0000-0002-9809-8493","orcid":"https://orcid.org/0000-0002-9809-8493","contributorId":27482,"corporation":false,"usgs":true,"family":"Paces","given":"J.B.","affiliations":[],"preferred":false,"id":402173,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Peterman, Z. E.","contributorId":63781,"corporation":false,"usgs":true,"family":"Peterman","given":"Z.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":402176,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70024329,"text":"70024329 - 2002 - Low-maturity Kulthieth Formation coal: A possible source of polycyclic aromatic hydrocarbons in benthic sediment of the northern Gulf of Alaska","interactions":[],"lastModifiedDate":"2012-03-12T17:20:00","indexId":"70024329","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1537,"text":"Environmental Forensics","active":true,"publicationSubtype":{"id":10}},"title":"Low-maturity Kulthieth Formation coal: A possible source of polycyclic aromatic hydrocarbons in benthic sediment of the northern Gulf of Alaska","docAbstract":"The successful application of forensic geology to contamination studies involving natural systems requires identification of appropriate endmembers and an understanding of the geologic setting and processes affecting the systems. Studies attempting to delineate the background, or natural, source for hydrocarbon contamination in Gulf of Alaska (GOA) benthic sediments have invoked a number of potential sources, including seep oils, source rocks, and coal. Oil seeps have subsequently been questioned as significant sources of hydrocarbons present in benthic sediments of the GOA in part because the pattern of relative polycyclic aromatic hydrocarbon (PAH) abundance characteristic of benthic GOA sediments is inconsistent with patterns typical of weathered seep oils. Likewise, native coal has been dismissed in part because ratios of labile hydrocarbons to total organic carbon (e.g. PAH:TOC) for Bering River coal field (BRCF) sources are too low - i.e. the coals are over mature - to be consistent with GOA sediments. We present evidence here that native coal may have been prematurely dismissed, because BRCF coals do not adequately represent the geochemical signatures of coals elsewhere in the Kulthieth Formation. Contrary to previous thought, Kulthieth Formation coals east of the BRCF have much higher PAH: TOC ratios, and the patterns of labile hydrocarbons in these low thermal maturity coals suggest a possible genetic relationship between Kulthieth Formation coals and nearby oil seeps on the Sullivan anticline. Analyses of low-maturity Kulthieth Formation coal indicate the low maturity coal is a significant source of PAH. Source apportionment models that neglect this source will underestimate the contribution of native coals to the regional background hydrocarbon signature. ?? Published by Elsevier Science Ltd. on behalf of AEHS.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Environmental Forensics","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1006/enfo.2002.0096","issn":"15275922","usgsCitation":"Van Kooten, G.K., Short, J., and Kolak, J., 2002, Low-maturity Kulthieth Formation coal: A possible source of polycyclic aromatic hydrocarbons in benthic sediment of the northern Gulf of Alaska: Environmental Forensics, v. 3, no. 3-4, p. 227-241, https://doi.org/10.1006/enfo.2002.0096.","startPage":"227","endPage":"241","numberOfPages":"15","costCenters":[],"links":[{"id":207159,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1006/enfo.2002.0096"},{"id":231850,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"3","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a4a5be4b0c8380cd68cde","contributors":{"authors":[{"text":"Van Kooten, G. K.","contributorId":41499,"corporation":false,"usgs":true,"family":"Van Kooten","given":"G.","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":400859,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Short, J.W.","contributorId":65631,"corporation":false,"usgs":true,"family":"Short","given":"J.W.","email":"","affiliations":[],"preferred":false,"id":400861,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kolak, J.J.","contributorId":46246,"corporation":false,"usgs":true,"family":"Kolak","given":"J.J.","email":"","affiliations":[],"preferred":false,"id":400860,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024678,"text":"70024678 - 2002 - Uranium-series disequilibrium in tuffs from Yucca Mountain, Nevada, as evidence of pore-fluid flow over the last million years","interactions":[],"lastModifiedDate":"2012-03-12T17:20:07","indexId":"70024678","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":835,"text":"Applied Geochemistry","active":true,"publicationSubtype":{"id":10}},"title":"Uranium-series disequilibrium in tuffs from Yucca Mountain, Nevada, as evidence of pore-fluid flow over the last million years","docAbstract":"Samples of tuff from boreholes drilled into fault zones in the Exploratory Studies Facility (ESF) and relatively unfractured rock of the Cross Drift tunnels, at Yucca Mountain, Nevada, have been analysed by U-series methods. This work is part of a project to verify the finding of fast flow-paths through the tuff to ESF level, indicated by the presence of 'bomb' 36Cl in pore fluids. Secular radioactive equilibrium in the U decay series, (i.e. when the radioactivity ratios 234U/238U, 230Th/234U and 226Ra/230Th all equal 1.00) might be expected if the tuff samples have not experienced radionuclide loss due to rock-water interaction occurring within the last million years. However, most fractured and unfractured samples were found to have a small deficiency of 234U (weighted mean 234U/238U=0.95??0.01) and a small excess of 230Th (weighted mean 230Th/234U 1.10??0.02). The 226Ra/230Th ratios are close to secular equilibrium (weighted mean = 0.94??0.07). These data indicate that 234U has been removed from the rock samples in the last ???350 ka, probably by pore fluids. Within the precision of the measurement, it would appear that 226Ra has not been mobilized and removed from the tuff, although there may be some localised 226Ra redistribution as suggested by a few ratio values that are significantly different from 1.0. Because both fractured and unfractured tuffs show approximately the same deficiency of 234U, this indicates that pore fluids are moving equally through fractured and unfractured rock, More importantly, fractured rock appears not to be a dominant pathway for groundwater flow (otherwise the ratio would be more strongly affected and the Th and Ra isotopic ratios would likely also show disequilibrium). Application of a simple mass-balance model suggests that surface infiltration rate is over an order of magnitude greater than the rate indicated by other infiltration models and that residence time of pore fluids at ESF level is about 400 a. Processes of U sorption, precipitation and re-solution are believed to be occurring and would account for these anomalous results but have not been included in the model. Despite the difficulties, the U-series data suggest that fractured rock, specifically the Sundance and Drill Hole Wash faults, are not preferred flow paths for groundwater flowing through the Topopah Spring tuff and, by implication, rapid-flow, within 50 a, from the surface to the level of the ESF is improbable. ?? 2002 Elsevier Science Ltd. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Applied Geochemistry","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/S0883-2927(02)00038-0","issn":"08832927","usgsCitation":"Gascoyne, M., Miller, N., and Neymark, L., 2002, Uranium-series disequilibrium in tuffs from Yucca Mountain, Nevada, as evidence of pore-fluid flow over the last million years: Applied Geochemistry, v. 17, no. 6, p. 781-792, https://doi.org/10.1016/S0883-2927(02)00038-0.","startPage":"781","endPage":"792","numberOfPages":"12","costCenters":[],"links":[{"id":233170,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207891,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0883-2927(02)00038-0"}],"volume":"17","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bbe00e4b08c986b329362","contributors":{"authors":[{"text":"Gascoyne, M.","contributorId":74918,"corporation":false,"usgs":true,"family":"Gascoyne","given":"M.","affiliations":[],"preferred":false,"id":402209,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Miller, N.H.","contributorId":37117,"corporation":false,"usgs":true,"family":"Miller","given":"N.H.","email":"","affiliations":[],"preferred":false,"id":402207,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Neymark, L.A. 0000-0003-4190-0278","orcid":"https://orcid.org/0000-0003-4190-0278","contributorId":56673,"corporation":false,"usgs":true,"family":"Neymark","given":"L.A.","affiliations":[],"preferred":false,"id":402208,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024680,"text":"70024680 - 2002 - Complex earthquake rupture and local tsunamis","interactions":[],"lastModifiedDate":"2022-07-22T16:42:09.304213","indexId":"70024680","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2314,"text":"Journal of Geophysical Research B: Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"Complex earthquake rupture and local tsunamis","docAbstract":"In contrast to far-field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes, there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment. From a global catalog of tsunami runup observations this variability is greatest for the most frequently occurring tsunamigenic subduction zone earthquakes in the magnitude range of 7 < Mw < 8.5. Variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment: variations in the water depth in the source region, the combination of higher slip and lower shear modulus at shallow depth, and rupture complexity in the form of heterogeneous slip distribution patterns. The focus of this study is on the effect that rupture complexity has on the local tsunami wave field. A wide range of slip distribution patterns are generated using a stochastic, self-affine source model that is consistent with the falloff of far-field seismic displacement spectra at high frequencies. The synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field. For shallow subduction zone earthquakes it is demonstrated that self-affine irregularities of the slip distribution result in significant variations in local tsunami amplitude. The effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles. For a test region along the Pacific coast of central Mexico, peak nearshore tsunami amplitude is calculated for a large number (N = 100) of synthetic slip distribution patterns, all with identical seismic moment (Mw = 8.1). Analysis of the results indicates that for earthquakes of a fixed location, geometry, and seismic moment, peak nearshore tsunami amplitude can vary by a factor of 3 or more. These results indicate that there is substantially more variation in the local tsunami wave field derived from the inherent complexity subduction zone earthquakes than predicted by a simple elastic dislocation model. Probabilistic methods that take into account variability in earthquake rupture processes are likely to yield more accurate assessments of tsunami hazards.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2000JB000139","usgsCitation":"Geist, E.L., 2002, Complex earthquake rupture and local tsunamis: Journal of Geophysical Research B: Solid Earth, v. 107, no. B5, p. ESE 2-1-ESE 2-15, https://doi.org/10.1029/2000JB000139.","productDescription":"15 p.","startPage":"ESE 2-1","endPage":"ESE 2-15","costCenters":[],"links":[{"id":478717,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/2000jb000139","text":"Publisher Index Page"},{"id":233203,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"107","issue":"B5","noUsgsAuthors":false,"publicationDate":"2002-05-02","publicationStatus":"PW","scienceBaseUri":"5059f90de4b0c8380cd4d3db","contributors":{"authors":[{"text":"Geist, Eric L","contributorId":118729,"corporation":false,"usgs":true,"family":"Geist","given":"Eric","email":"","middleInitial":"L","affiliations":[],"preferred":false,"id":402212,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70024363,"text":"70024363 - 2002 - Sea-cliff erosion as a function of beach changes and extreme wave runup during the 1997-1998 El Nino","interactions":[],"lastModifiedDate":"2014-09-03T12:00:52","indexId":"70024363","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2667,"text":"Marine Geology","active":true,"publicationSubtype":{"id":10}},"title":"Sea-cliff erosion as a function of beach changes and extreme wave runup during the 1997-1998 El Nino","docAbstract":"Over time scales of hundreds to thousands of years, the net longshore sand transport direction along the central California coast has been driven to the south by North Pacific winter swell. In contrast, during the El Nin??o winter of 1997-1998, comparisons of before and after airborne lidar surveys showed sand was transported from south to north and accumulated on the south sides of resistant headlands bordering pocket beaches. This resulted in significant beach erosion at the south ends of pocket beaches and deposition in the north ends. Coincident with the south-to-north redistribution of sand, shoreline morphology became prominently cuspate with longshore wavelengths of 400-700 m. The width and elevation of beaches were least where maximum shoreline erosion occurred, preferentially exposing cliffs to wave attack. The resulting erosional hotspots typically were located in the embayments of giant cusps in the southern end of the pocket beaches. The observed magnitude of sea cliff retreat, which reached 14 m, varied with the number of hours that extreme wave runup exceeded certain thresholds representing the protective capacity of the beach during the El Nin??o winter. A threshold representing the width of the beach performed better than a threshold representing the elevation of the beach. The magnitude of cliff erosion can be scaled using a simple model based on the cross-shore distance that extreme wave runup exceeded the pre-winter cliff position. Cliff erosion appears to be a balance between terrestrial mass wasting processes, which tend to decrease the cliff slope, and wave attack, which removes debris and erodes the cliff base increasing the cliff slope. ?? 2002 Elsevier Science B.V. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Marine Geology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/S0025-3227(02)00316-X","issn":"00253227","usgsCitation":"Sallenger, A.H., Krabill, W., Brock, J., Swift, R., Manizade, S., and Stockdon, H., 2002, Sea-cliff erosion as a function of beach changes and extreme wave runup during the 1997-1998 El Nino: Marine Geology, v. 187, no. 3-4, p. 279-297, https://doi.org/10.1016/S0025-3227(02)00316-X.","startPage":"279","endPage":"297","numberOfPages":"19","costCenters":[],"links":[{"id":231815,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207142,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0025-3227(02)00316-X"}],"volume":"187","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b8801e4b08c986b316770","contributors":{"authors":[{"text":"Sallenger, A. H. Jr.","contributorId":8818,"corporation":false,"usgs":true,"family":"Sallenger","given":"A.","suffix":"Jr.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":400999,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Krabill, W.","contributorId":86524,"corporation":false,"usgs":true,"family":"Krabill","given":"W.","affiliations":[],"preferred":false,"id":401003,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Brock, J. 0000-0002-5289-9332","orcid":"https://orcid.org/0000-0002-5289-9332","contributorId":71658,"corporation":false,"usgs":true,"family":"Brock","given":"J.","affiliations":[],"preferred":false,"id":401001,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Swift, R.","contributorId":87716,"corporation":false,"usgs":true,"family":"Swift","given":"R.","affiliations":[],"preferred":false,"id":401004,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Manizade, S.","contributorId":76502,"corporation":false,"usgs":true,"family":"Manizade","given":"S.","affiliations":[],"preferred":false,"id":401002,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Stockdon, H.","contributorId":71351,"corporation":false,"usgs":true,"family":"Stockdon","given":"H.","affiliations":[],"preferred":false,"id":401000,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70024724,"text":"70024724 - 2002 - Source of solutes to the coastal sabkha of Abu Dhabi","interactions":[],"lastModifiedDate":"2022-01-14T17:15:29.997277","indexId":"70024724","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1786,"text":"Geological Society of America Bulletin","active":true,"publicationSubtype":{"id":10}},"title":"Source of solutes to the coastal sabkha of Abu Dhabi","docAbstract":"An ascending-brine model is proposed to address the observed isotope geochemistry, solute composition, and solute and water fluxes in the coastal sabkha of the Emirate of Abu Dhabi. Mass-balance measurements document that >95% of the solutes are derived from ascending continental brines; minor amounts are derived from rainfall and from groundwater entering from upgradient areas. Nearly 100% of the annual water loss is from evaporation and not lateral discharge. Direct rainfall on the sabkha and subsequent recharge to the underlying aquifer account for ~ 90% of the annual water input to the system; the remaining 10% comes from both lateral and ascending groundwater flow. Thus, the water and solutes in this system are from different sources. Solute concentrations of conservative (i.e., nonreactive) elements in the coastal, sabkha-covered aquifer are consistent with the fluid pore volumes of ascending brine calculated from hydrologic properties. Calcium to sulfate ratios and sulfur isotopes are consistent with this source of solute from the underlying Tertiary formations. Recharging rainwater dissolves halite and other soluble minerals on the surface, causing the solution to become more dense and sink to the bottom of the aquifer where it vertically mixes with less dense ascending brines. Solutes are returned to the surface by capillary forces and recycled or lost from the system by eolian or fluvial processes. Thus, the system becomes vertically mixed, consistent with the presence of tritium throughout the aquifer; but there is essentially no horizontal mixing of seawater with groundwater. The observed seawater solutes in the supratidal zone come from interstitial seawater trapped by the rapid progradation of the sediments into the Arabian Gulf and are not refluxed or laterally mixed. The ascending-brine model contrasts significantly with both the seawater-flooding and evaporative-pumping models previously proposed as a source of solutes to the coastal sabkha of the Emirate of Abu Dhabi. Use of these earlier models leads to incorrect conclusions and raises serious questions about their applicability in the evaluation of sabkhat in the geologic record.","language":"English","publisher":"GeoScienceWorld","doi":"10.1130/0016-7606(2002)114<0259:SOSTTC>2.0.CO;2","usgsCitation":"Wood, W., Sanford, W., and Al Habshi, A., 2002, Source of solutes to the coastal sabkha of Abu Dhabi: Geological Society of America Bulletin, v. 114, no. 3, p. 259-268, https://doi.org/10.1130/0016-7606(2002)114<0259:SOSTTC>2.0.CO;2.","productDescription":"10 p.","startPage":"259","endPage":"268","costCenters":[],"links":[{"id":233314,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United Arab Emirates","city":"Abu Dhabi","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n 54.228515625,\n 24.37712083961039\n ],\n [\n 54.33837890624999,\n 24.367113562651262\n ],\n [\n 55.26123046875,\n 24.926294766395593\n ],\n [\n 55.843505859375,\n 25.72073513441208\n ],\n [\n 55.447998046875,\n 25.562265014427492\n ],\n [\n 54.964599609375,\n 25.16517336866393\n ],\n [\n 54.228515625,\n 24.37712083961039\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"114","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b9333e4b08c986b31a362","contributors":{"authors":[{"text":"Wood, W.W.","contributorId":21974,"corporation":false,"usgs":true,"family":"Wood","given":"W.W.","email":"","affiliations":[],"preferred":false,"id":402420,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Sanford, W. E. 0000-0002-6624-0280","orcid":"https://orcid.org/0000-0002-6624-0280","contributorId":102112,"corporation":false,"usgs":true,"family":"Sanford","given":"W. E.","affiliations":[],"preferred":false,"id":402422,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Al Habshi, A.R.S.","contributorId":60416,"corporation":false,"usgs":true,"family":"Al Habshi","given":"A.R.S.","email":"","affiliations":[],"preferred":false,"id":402421,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024733,"text":"70024733 - 2002 - Long-term climate patterns in Alaskan surface temperature and precipitation and their biological consequences","interactions":[],"lastModifiedDate":"2017-04-10T09:54:31","indexId":"70024733","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1944,"text":"IEEE Transactions on Geoscience and Remote Sensing","active":true,"publicationSubtype":{"id":10}},"title":"Long-term climate patterns in Alaskan surface temperature and precipitation and their biological consequences","docAbstract":"Mean monthly climate maps of Alaskan surface temperature and precipitation produced by the parameter-elevation regression on independent slopes model (PRISM) were analyzed. Alaska is divided into interior and coastal zones with consistent but different climatic variability separated by a transition region; it has maximum interannual variability but low long-term mean variability. Pacific decadal oscillation (PDO)- and El Nino Southern Oscillation (ENSO)-type events influence Alaska surface temperatures weakly (1-2/spl deg/C) statewide. PDO has a stronger influence than ENSO on precipitation but its influence is largely localized to coastal central Alaska. The strongest influence of Arctic oscillation (AO) occurs in northern and interior Alaskan precipitation. Four major ecosystems are defined. A major eco-transition zone occurs between the interior boreal forest and the coastal rainforest. Variability in insolation, surface temperature, precipitation, continentality, and seasonal changes in storm track direction explain the mapped ecosystems. Lack of westward expansion of the interior boreal forest into the western shrub tundra is influenced by the coastal marine boundary layer (enhanced cloud cover, reduced insolation, cooler surface and soil temperatures).
","language":"English","publisher":"IEEE","doi":"10.1109/TGRS.2002.1010902","issn":"01962892","usgsCitation":"Simpson, J.J., Hufford, G.L., Fleming, M.D., Berg, J.S., and Ashton, J., 2002, Long-term climate patterns in Alaskan surface temperature and precipitation and their biological consequences: IEEE Transactions on Geoscience and Remote Sensing, v. 40, no. 5, p. 1164-1184, https://doi.org/10.1109/TGRS.2002.1010902.","productDescription":"21 p.","startPage":"1164","endPage":"1184","numberOfPages":"21","costCenters":[{"id":222,"text":"Earth Resources Observation and Science (EROS) Center","active":true,"usgs":true}],"links":[{"id":232853,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207694,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1109/TGRS.2002.1010902"}],"volume":"40","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a497fe4b0c8380cd6866b","contributors":{"authors":[{"text":"Simpson, James J.","contributorId":58811,"corporation":false,"usgs":true,"family":"Simpson","given":"James","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":402445,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hufford, Gary L.","contributorId":78502,"corporation":false,"usgs":true,"family":"Hufford","given":"Gary","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":402446,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Fleming, Michael D.","contributorId":98816,"corporation":false,"usgs":true,"family":"Fleming","given":"Michael","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":402449,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Berg, Jared S.","contributorId":78912,"corporation":false,"usgs":true,"family":"Berg","given":"Jared","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":402447,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Ashton, J.B.","contributorId":95653,"corporation":false,"usgs":true,"family":"Ashton","given":"J.B.","email":"","affiliations":[],"preferred":false,"id":402448,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70024734,"text":"70024734 - 2002 - Control of strong ground motion of mining-induced earthquakes by the strength of the seismogenic rock mass","interactions":[],"lastModifiedDate":"2013-03-24T17:02:58","indexId":"70024734","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2569,"text":"Journal of the South African Institute of Mining and Metallurgy","active":true,"publicationSubtype":{"id":10}},"title":"Control of strong ground motion of mining-induced earthquakes by the strength of the seismogenic rock mass","docAbstract":"The shear stress ?? that can be sustained by the rock mass in the environs of a mining-induced earthquake controls the near-fault peak ground velocity v of that event according to v???0.25(??/G) ??, where ?? is the shear wave speed and G is the modulus of rigidity. To estimate ?? at mining depths, I review the results of four studies involving Witwatersrand tremors that relate to the bulk shear strength. The first and most general analysis uses the common assumptions that the seismogenic crust is pervasively faulted, has hydrostatic pore pressure before mining, and an extensional stress state that is close to failure. Mining operations reduce the pore pressure to zero within the mine and redistribute the stresses such that, in localized regions, the state of stress is again at the point of failure. Laboratory friction experiments can be used to estimate ?? in the zero-pore-pressure regime. Second, model calculations of states of stress in the vicinity of milling at about 3 km depth indicated the shear stress available to cause faulting near the centre of a distribution of induced earthquakes. Third, laboratory experiments combined with microscopic analyses of fault gouge from the rupture zone of a mining-induced event provided an estimate of the average shear stress acting on the fault to cause this earthquake at a depth of 2 km. Fourth, moment tensors determined for mining- induced earthquakes usually show substantial implosive components, from which it is straightforward to estimate ??. These four different analyses yield estimates of ?? that fall in the range 30 to 61 MPa which implies that near-fault particle velocities could he as high as about 1.5 m/s. To the extent that the causative fault ruptures previously intact rock, both ?? and v, in localized regions, could be several times higher than 61 MPa and 1.5 m/s.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of the South African Institute of Mining and Metallurgy","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","issn":"0038223X","usgsCitation":"McGarr, A., 2002, Control of strong ground motion of mining-induced earthquakes by the strength of the seismogenic rock mass: Journal of the South African Institute of Mining and Metallurgy, v. 102, no. 4, p. 225-229.","startPage":"225","endPage":"229","numberOfPages":"5","costCenters":[],"links":[{"id":232887,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":269950,"type":{"id":11,"text":"Document"},"url":"https://www.saimm.co.za/Journal/v102n04p225.pdf"}],"volume":"102","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059fb44e4b0c8380cd4ddb8","contributors":{"authors":[{"text":"McGarr, Art 0000-0001-9769-4093","orcid":"https://orcid.org/0000-0001-9769-4093","contributorId":43491,"corporation":false,"usgs":true,"family":"McGarr","given":"Art","affiliations":[],"preferred":false,"id":402450,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70024735,"text":"70024735 - 2002 - Tectonics and distribution of gold deposits in China - An overview","interactions":[],"lastModifiedDate":"2022-08-15T14:41:44.358289","indexId":"70024735","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2746,"text":"Mineralium Deposita","active":true,"publicationSubtype":{"id":10}},"title":"Tectonics and distribution of gold deposits in China - An overview","docAbstract":"Gold exploration in China has expanded rapidly during the last two decades since a modern approach to economic development has become a national priority. China currently produces 180 tonnes (t) of gold annually, which is still significantly less than South Africa, USA, and Australia. However, China is now recognized as possessing significant gold resources in a wide range of mineral deposit types. Present estimates of gold resources in China exceed 4,500 t, which comprise 60% in gold-only deposits, more than 25% in base metal-rich skarn, porphyry, and vein deposits, and more than 10% in placer accumulations. The major gold provinces in China formed during the main episodes of Phanerozoic tectonism. Such tectonism involved interaction of China's three major Precambrian cratons, North China, Tarim, and Yangtze (or South China when combined with Cathaysia block), with the Angara (or Siberian), Kazakhstan–Kyrgyzstan, and Indian cratons. Resulting collisions included deformation of accreted oceanic sequences between the cratonic blocks. The most important ore-forming orogenies were (1) the late Paleozoic Variscan (405–270 Ma), which led to amalgamation of the Angara, North China and Yangtze cratons, (2) the Indosinian (270–208 Ma), which led to the collision of North China and South China cratons, (3) the Yanshanian (208–90 Ma), which was largely influenced by the subduction of the Izanagi–Pacific plates beneath eastern China, and (4) the Himalayan (<90 Ma) indentation of the Indian continent into Eurasia. No important Precambrian gold systems are recognized in China, mainly because of reworking of exposed Precambrian rocks by these younger orogenies, but there are a few Caledonian (600–405 Ma) gold-bearing systems in northern Xinjiang. Most of China's orogenic, epithermal, and Carlin-like gold deposits are in the reworked margins of major cratonic blocks and in metasedimentary rock-dominated fold belts adjacent to these margins. Accordingly, the major gold provinces are present along the northern, southeastern and southern margins of the North China craton, along the southwestern and northwestern margins of the Yangtze craton, in the Tianshan and Altayshan orogenic belts in northern Xinjiang, and throughout the southeastern China fold belt. Gold-placer deposits derived from these primary deposits are concentrated in the northernmost part of northeastern China and along the northwestern margin of the Yangtze craton. The major provinces with significant gold in porphyry-related copper systems and base metal skarns are present in the Yangtze River area along the northeastern and southeastern margin of the Yangtze craton, in the fold belt in southwestern China, and scattered through northern China. Three-quarters of the Chinese gold-only deposits occur within the North China craton margins. Half are located in the uplifted Precambrian metamorphic rocks and most of the remainder are hosted in the Phanerozoic granitoids that intruded the reworked Precambrian terranes. The abundance of granite-hosted gold contrasts the North China craton with other Precambrian cratons, such as those in Western Australia, central Canada, and Zimbabwe, where gold is mainly hosted in the Archean greenstone belts. This difference may be explained by the multiple episodes of Phanerozoic tectonism along the North China craton margins resulting from the collision of the Angara, North China, and South China cratons, and from subduction of the Izanagi–Pacific oceanic plates underneath the eastern China continent.
","language":"English","publisher":"Springer Link","doi":"10.1007/s00126-001-0237-4","usgsCitation":"Zhou, T., Goldfarb, R.J., and Phillips, N.G., 2002, Tectonics and distribution of gold deposits in China - An overview: Mineralium Deposita, v. 37, no. 3-4, p. 249-282, https://doi.org/10.1007/s00126-001-0237-4.","productDescription":"34 p.","startPage":"249","endPage":"282","numberOfPages":"34","costCenters":[{"id":171,"text":"Central Mineral and Environmental Resources Science 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T.","contributorId":93248,"corporation":false,"usgs":true,"family":"Zhou","given":"T.","email":"","affiliations":[],"preferred":false,"id":402452,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Goldfarb, Richard J. goldfarb@usgs.gov","contributorId":1205,"corporation":false,"usgs":true,"family":"Goldfarb","given":"Richard","email":"goldfarb@usgs.gov","middleInitial":"J.","affiliations":[{"id":171,"text":"Central Mineral and Environmental Resources Science Center","active":true,"usgs":true}],"preferred":false,"id":402451,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Phillips, Neil G.","contributorId":295239,"corporation":false,"usgs":false,"family":"Phillips","given":"Neil","email":"","middleInitial":"G.","affiliations":[],"preferred":false,"id":402453,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024736,"text":"70024736 - 2002 - A statistical evaluation of non-ergodic variogram estimators","interactions":[],"lastModifiedDate":"2012-03-12T17:20:14","indexId":"70024736","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1573,"text":"Environmental and Ecological Statistics","active":true,"publicationSubtype":{"id":10}},"title":"A statistical evaluation of non-ergodic variogram estimators","docAbstract":"Geostatistics is a set of statistical techniques that is increasingly used to characterize spatial dependence in spatially referenced ecological data. A common feature of geostatistics is predicting values at unsampled locations from nearby samples using the kriging algorithm. Modeling spatial dependence in sampled data is necessary before kriging and is usually accomplished with the variogram and its traditional estimator. Other types of estimators, known as non-ergodic estimators, have been used in ecological applications. Non-ergodic estimators were originally suggested as a method of choice when sampled data are preferentially located and exhibit a skewed frequency distribution. Preferentially located samples can occur, for example, when areas with high values are sampled more intensely than other areas. In earlier studies the visual appearance of variograms from traditional and non-ergodic estimators were compared. Here we evaluate the estimators' relative performance in prediction. We also show algebraically that a non-ergodic version of the variogram is equivalent to the traditional variogram estimator. Simulations, designed to investigate the effects of data skewness and preferential sampling on variogram estimation and kriging, showed the traditional variogram estimator outperforms the non-ergodic estimators under these conditions. We also analyzed data on carabid beetle abundance, which exhibited large-scale spatial variability (trend) and a skewed frequency distribution. Detrending data followed by robust estimation of the residual variogram is demonstrated to be a successful alternative to the non-ergodic approach.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Environmental and Ecological Statistics","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1023/A:1013771109591","issn":"13528505","usgsCitation":"Curriero, F., Hohn, M., Liebhold, A., and Lele, S., 2002, A statistical evaluation of non-ergodic variogram estimators: Environmental and Ecological Statistics, v. 9, no. 1, p. 89-110, https://doi.org/10.1023/A:1013771109591.","startPage":"89","endPage":"110","numberOfPages":"22","costCenters":[],"links":[{"id":207740,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1023/A:1013771109591"},{"id":232922,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"9","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e5afe4b0c8380cd46efe","contributors":{"authors":[{"text":"Curriero, F.C.","contributorId":95237,"corporation":false,"usgs":true,"family":"Curriero","given":"F.C.","email":"","affiliations":[],"preferred":false,"id":402456,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hohn, M.E.","contributorId":98470,"corporation":false,"usgs":true,"family":"Hohn","given":"M.E.","email":"","affiliations":[],"preferred":false,"id":402457,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Liebhold, A.M.","contributorId":91663,"corporation":false,"usgs":true,"family":"Liebhold","given":"A.M.","affiliations":[],"preferred":false,"id":402455,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Lele, S.R.","contributorId":49959,"corporation":false,"usgs":true,"family":"Lele","given":"S.R.","email":"","affiliations":[],"preferred":false,"id":402454,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":1016157,"text":"1016157 - 2002 - Predation by Oregon spotted frogs (Rana pretiosa) on Western toads (Bufo boreas) in Oregon, USA","interactions":[],"lastModifiedDate":"2021-12-09T16:03:21.278472","indexId":"1016157","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":737,"text":"American Midland Naturalist","active":true,"publicationSubtype":{"id":10}},"displayTitle":"Predation by Oregon spotted frogs (Rana pretiosa) on Western toads (Bufo boreas) in Oregon, USA","title":"Predation by Oregon spotted frogs (Rana pretiosa) on Western toads (Bufo boreas) in Oregon, USA","docAbstract":"Toads of the genus Bufo co-occur with true frogs (family Ranidae) throughout their North American ranges. Yet, Bufo are rarely reported as prey for ranid frogs, perhaps due to dermal toxins that afford them protection from some predators. We report field observations from four different localities demonstrating that Oregon spotted frogs (Rana pretiosa) readily consume juvenile western toads (Bufo boreas) at breeding sites in Oregon. Unpalatability thought to deter predators of selected taxa and feeding mode may not protect juvenile stages of western toads from adult Oregon spotted frogs. Activity of juvenile western toads can elicit ambush behavior by Oregon spotted frog adults. Our review of published literature suggests that regular consumption of toadlets sets Oregon spotted frogs apart from most North American ranid frogs. Importance of the trophic context of juvenile western toads as a seasonally important resource to Oregon spotted frogs needs critical investigation.
","language":"English","publisher":"BioOne","doi":"10.1674/0003-0031(2002)147[0145:PBOSFR]2.0.CO;2","usgsCitation":"Pearl, C., and Hayes, M., 2002, Predation by Oregon spotted frogs (Rana pretiosa) on Western toads (Bufo boreas) in Oregon, USA: American Midland Naturalist, v. 147, no. 1, p. 145-152, https://doi.org/10.1674/0003-0031(2002)147[0145:PBOSFR]2.0.CO;2.","productDescription":"8 p.","startPage":"145","endPage":"152","costCenters":[{"id":290,"text":"Forest and Rangeland Ecosystem Science Center","active":false,"usgs":true}],"links":[{"id":134074,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Oregon","otherGeospatial":"Oregon Cascade Range","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -123.42041015624999,\n 41.95131994679697\n ],\n [\n -121.92626953124999,\n 41.95131994679697\n ],\n [\n -121.92626953124999,\n 46.01222384063236\n ],\n [\n -123.42041015624999,\n 46.01222384063236\n ],\n [\n -123.42041015624999,\n 41.95131994679697\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"147","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4acfe4b07f02db680524","contributors":{"authors":[{"text":"Pearl, Christopher A. 0000-0003-2943-7321","orcid":"https://orcid.org/0000-0003-2943-7321","contributorId":84316,"corporation":false,"usgs":true,"family":"Pearl","given":"Christopher A.","affiliations":[{"id":289,"text":"Forest and Rangeland Ecosys Science Center","active":true,"usgs":true}],"preferred":false,"id":323648,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hayes, M.P.","contributorId":56174,"corporation":false,"usgs":false,"family":"Hayes","given":"M.P.","email":"","affiliations":[],"preferred":false,"id":323647,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70024824,"text":"70024824 - 2002 - Comments on baseline correction of digital strong-motion data: Examples from the 1999 Hector Mine, California, earthquake","interactions":[],"lastModifiedDate":"2012-03-12T17:20:08","indexId":"70024824","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1135,"text":"Bulletin of the Seismological Society of America","onlineIssn":"1943-3573","printIssn":"0037-1106","active":true,"publicationSubtype":{"id":10}},"title":"Comments on baseline correction of digital strong-motion data: Examples from the 1999 Hector Mine, California, earthquake","docAbstract":"Residual displacements for large earthquakes can sometimes be determined from recordings on modern digital instruments, but baseline offsets of unknown origin make it difficult in many cases to do so. To recover the residual displacement, we suggest tailoring a correction scheme by studying the character of the velocity obtained by integration of zeroth-order-corrected acceleration and then seeing if the residual displacements are stable when the various parameters in the particular correction scheme are varied. For many seismological and engineering purposes, however, the residual displacement are of lesser importance than ground motions at periods less than about 20 sec. These ground motions are often recoverable with simple baseline correction and low-cut filtering. In this largely empirical study, we illustrate the consequences of various correction schemes, drawing primarily from digital recordings of the 1999 Hector Mine, California, earthquake. We show that with simple processing the displacement waveforms for this event are very similar for stations separated by as much as 20 km. We also show that a strong pulse on the transverse component was radiated from the Hector Mine earthquake and propagated with little distortion to distances exceeding 170 km; this pulse leads to large response spectral amplitudes around 10 sec.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Bulletin of the Seismological Society of America","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1785/0120000926","issn":"00371106","usgsCitation":"Boore, D., Stephens, C., and Joyner, W.B., 2002, Comments on baseline correction of digital strong-motion data: Examples from the 1999 Hector Mine, California, earthquake: Bulletin of the Seismological Society of America, v. 92, no. 4, p. 1543-1560, https://doi.org/10.1785/0120000926.","startPage":"1543","endPage":"1560","numberOfPages":"18","costCenters":[],"links":[{"id":233071,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207833,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1785/0120000926"}],"volume":"92","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f7f2e4b0c8380cd4cdc8","contributors":{"authors":[{"text":"Boore, D.M. 0000-0002-8605-9673","orcid":"https://orcid.org/0000-0002-8605-9673","contributorId":64226,"corporation":false,"usgs":true,"family":"Boore","given":"D.M.","affiliations":[],"preferred":false,"id":402752,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Stephens, C.D.","contributorId":18752,"corporation":false,"usgs":true,"family":"Stephens","given":"C.D.","email":"","affiliations":[],"preferred":false,"id":402751,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Joyner, W. B.","contributorId":70746,"corporation":false,"usgs":true,"family":"Joyner","given":"W.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":402753,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024738,"text":"70024738 - 2002 - Regional estimates of radiated seismic energy","interactions":[],"lastModifiedDate":"2023-04-24T15:03:59.108845","indexId":"70024738","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1135,"text":"Bulletin of the Seismological Society of America","onlineIssn":"1943-3573","printIssn":"0037-1106","active":true,"publicationSubtype":{"id":10}},"title":"Regional estimates of radiated seismic energy","docAbstract":"We revise the spectral technique for estimating radiated energy from recordings of large earthquakes at regional distances (Δ < 200 km) by correcting for geometric spreading and for site amplification as explicit functions of frequency. We analyze 65 recordings of the 1999 Hector Mine earthquake as functions of frequency, distance, and azimuth. For r > 27.5 km from the source, we model the geometrical spreading of the regional wavefield as r–γ where γ = 0.5 for f ≤ 0.2 Hz and γ = 0.7 for f ≥ 0.25 Hz. We fit the spectral falloff with distance using a frequency-dependent attenuation Q = 400(f /1.5)0.6, where Q = 400 for f ≤ 1.5 Hz. There is little directivity apparent in the corrected velocity spectra: the velocity spectra observed to the northwest along strike are amplified by a factor of 2.5 from 0.3 to 1.0 Hz and those to the southeast are amplified by a factor of 1.6 from 0.3 to 0.7 Hz. We group the stations in NEHRP site classes, using average 1-D velocity structures to estimate site amplification as a function of frequency and assuming 0.40 ≤ κ ≤ 0.55 sec for the near-surface attenuation. We increase the amplification of the soft-soil sites from 0.1 to 1.0 Hz by a factor that reaches 1.7 at 0.3 Hz because they are more strongly amplified than the NEHRP-D velocity structure predicts. We combine the 65 single-station estimates of radiated energy using an equal-azimuth weighting scheme that compensates for station distribution and incorporates the observed directivity, yielding a regional estimate of Es = 3.4 ± 0.7 × 1022 dyne cm. This regional estimate of radiated energy corresponds closely to the teleseismic estimate of Es = 3.2 × 1022 dyne cm.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/0120000932","usgsCitation":"Boatwright, J., Choy, G.L., and Seekins, L.C., 2002, Regional estimates of radiated seismic energy: Bulletin of the Seismological Society of America, v. 92, no. 4, p. 1241-1255, https://doi.org/10.1785/0120000932.","productDescription":"15 p.","startPage":"1241","endPage":"1255","numberOfPages":"15","costCenters":[],"links":[{"id":232958,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"92","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"50e4a4c5e4b0e8fec6cdbc5f","contributors":{"authors":[{"text":"Boatwright, J.","contributorId":87297,"corporation":false,"usgs":true,"family":"Boatwright","given":"J.","email":"","affiliations":[],"preferred":false,"id":402461,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Choy, G. L. 0000-0002-0217-5555","orcid":"https://orcid.org/0000-0002-0217-5555","contributorId":78322,"corporation":false,"usgs":true,"family":"Choy","given":"G.","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":402460,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Seekins, L. C.","contributorId":99561,"corporation":false,"usgs":true,"family":"Seekins","given":"L.","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":402462,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024398,"text":"70024398 - 2002 - Fasting modifies Aroclor 1254 impact on plasma cortisol, glucose and lactate responses to a handling disturbance in Arctic charr","interactions":[],"lastModifiedDate":"2017-05-06T15:21:59","indexId":"70024398","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1296,"text":"Comparative Biochemistry and Physiology, Part C: Toxicology & Pharmacology","active":true,"publicationSubtype":{"id":10}},"title":"Fasting modifies Aroclor 1254 impact on plasma cortisol, glucose and lactate responses to a handling disturbance in Arctic charr","docAbstract":"Integrated effects of polychlorinated biphenyl (PCB) and nutritional status on responses to handling disturbance were investigated in the Arctic charr (Salvelinus alpinus). The fish were orally contaminated with Aroclor 1254 and held either with or without food for 5 months before they were subjected to a 10-min handling disturbance. Food-deprived fish were given 0, 1, 10 or 100 mg PCB kg−1 and the fed fish 0 or 100 mg PCB kg−1. Plasma cortisol, glucose and lactate levels were measured at 0 (pre-handling), 1, 3, 6 and 23 h after the handling disturbance. Food-deprived control fish had elevated plasma cortisol levels compared with fed fish before handling. These basal cortisol levels were suppressed by PCB in food-deprived fish, and elevated by PCB in fed fish. The immediate cortisol and glucose responses to handling disturbance were suppressed by PCB in a dose-dependent way in food-deprived fish. Although these responses were also lowered by PCB in the fed fish, the effect was much less pronounced than in food-deprived fish. There were only minor effects on plasma lactate responses. Our findings suggest that the stress responses of the Arctic charr are compromised by PCB and that the long-term fasting, typical of high-latitude fish, makes these species particularly sensitive to organochlorines such as PCB.
","language":"English","publisher":"Elsevier","doi":"10.1016/S1532-0456(02)00069-8","issn":"15320456","usgsCitation":"Jorgensen, E., Vijayan, M., Aluru, N., and Maule, A., 2002, Fasting modifies Aroclor 1254 impact on plasma cortisol, glucose and lactate responses to a handling disturbance in Arctic charr: Comparative Biochemistry and Physiology, Part C: Toxicology & Pharmacology, v. 132, no. 2, p. 235-245, https://doi.org/10.1016/S1532-0456(02)00069-8.","productDescription":"11 p.","startPage":"235","endPage":"245","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":654,"text":"Western Fisheries Research Center","active":true,"usgs":true}],"links":[{"id":232038,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"132","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a0effe4b0c8380cd536f6","contributors":{"authors":[{"text":"Jorgensen, E.H.","contributorId":13782,"corporation":false,"usgs":true,"family":"Jorgensen","given":"E.H.","affiliations":[],"preferred":false,"id":401120,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Vijayan, M.M.","contributorId":33087,"corporation":false,"usgs":true,"family":"Vijayan","given":"M.M.","email":"","affiliations":[],"preferred":false,"id":401121,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Aluru, N.","contributorId":80454,"corporation":false,"usgs":true,"family":"Aluru","given":"N.","email":"","affiliations":[],"preferred":false,"id":401123,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Maule, A.G.","contributorId":45067,"corporation":false,"usgs":true,"family":"Maule","given":"A.G.","email":"","affiliations":[],"preferred":false,"id":401122,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70024827,"text":"70024827 - 2002 - Cripple Creek and other alkaline-related gold deposits in the Southern Rocky Mountains, USA: Influence of regional tectonics","interactions":[],"lastModifiedDate":"2022-08-15T14:34:52.860218","indexId":"70024827","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2746,"text":"Mineralium Deposita","active":true,"publicationSubtype":{"id":10}},"title":"Cripple Creek and other alkaline-related gold deposits in the Southern Rocky Mountains, USA: Influence of regional tectonics","docAbstract":"Alkaline-related epithermal vein, breccia, disseminated, skarn, and porphyry gold deposits form a belt in the southern Rocky Mountains along the eastern edge of the North American Cordillera. Alkaline igneous rocks and associated hydrothermal deposits formed at two times. The first was during the Laramide orogeny (about 70–40 Ma), with deposits restricted spatially to the Colorado mineral belt (CMB). Other alkaline igneous rocks and associated gold deposits formed later, during the transition from a compressional to an extensional regime (about 35–27 Ma). These younger rocks and associated deposits are more widespread, following the Rocky Mountain front southward, from Cripple Creek in Colorado through New Mexico. All of these deposits are on the eastern margin of the Cordillera, with voluminous calc-alkaline rocks to the west. The largest deposits in the belt include Cripple Creek and those in the CMB. The most important factor in the formation of all of the gold deposits was the near-surface emplacement of relatively oxidized volatile-rich alkaline magmas. Strontium and lead isotope compositions suggest that the source of the magmas was subduction-modified subcontinental lithosphere. However, Cripple Creek alkaline rocks and older Laramide alkaline rocks in the CMB that were emplaced through hydrously altered LREE-enriched rocks of the Colorado (Yavapai) province have 208Pb/204Pb ratios that suggest these magmas assimilated and mixed with significant amounts of lower crust. The anomalously hot, thick, and light crust beneath Colorado may have been a catalyst for large-scale transfer of volatiles and crustal melting. Increased dissolved H2O (and CO2, F, Cl) of these magmas may have resulted in more productive gold deposits due to more efficient magmatic-hydrothermal systems. High volatile contents may also have promoted Te and V enrichment, explaining the presence of fluorite, roscoelite (vanadium-rich mica) and tellurides in the CMB deposits and Cripple Creek as opposed to deposits to the south. Deep-seated structures of regional extent that formed during the Proterozoic allowed the magmas to rise to shallow crustal levels. Proterozoic sites of intrusions at 1.65, 1.4, and 1.1 Ga were also important precursors to alkaline-related gold deposits. Many of the larger gold deposits are located at sites of Proterozoic intrusions, and are localized at the intersection of northeast-trending ductile shear zones formed during Mesoproterozoic deformation, and an important north-trending fault formed during 1.1 Ga rifting.
","language":"English","publisher":"Springer Link","doi":"10.1007/s00126-001-0229-4","usgsCitation":"Kelley, K.D., and Ludington, S., 2002, Cripple Creek and other alkaline-related gold deposits in the Southern Rocky Mountains, USA: Influence of regional tectonics: Mineralium Deposita, v. 37, no. 1, p. 38-60, https://doi.org/10.1007/s00126-001-0229-4.","productDescription":"23 p.","startPage":"38","endPage":"60","numberOfPages":"23","costCenters":[{"id":171,"text":"Central Mineral and Environmental Resources Science Center","active":true,"usgs":true}],"links":[{"id":233143,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Colorado, New Mexico","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -110,\n 31\n ],\n [\n -102,\n 31\n ],\n [\n -102,\n 42\n ],\n [\n -110,\n 42\n ],\n [\n -110,\n 31\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"37","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059fcafe4b0c8380cd4e3a4","contributors":{"authors":[{"text":"Kelley, Karen D. kdkelley@usgs.gov","contributorId":431,"corporation":false,"usgs":true,"family":"Kelley","given":"Karen","email":"kdkelley@usgs.gov","middleInitial":"D.","affiliations":[{"id":171,"text":"Central Mineral and Environmental Resources Science Center","active":true,"usgs":true}],"preferred":false,"id":402765,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ludington, Steve","contributorId":60657,"corporation":false,"usgs":true,"family":"Ludington","given":"Steve","affiliations":[],"preferred":false,"id":402766,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70024739,"text":"70024739 - 2002 - Preliminary comparison of landscape pattern-normalized difference vegetation index (NDVI) relationships to central plains stream conditions","interactions":[],"lastModifiedDate":"2022-07-22T16:08:14.104924","indexId":"70024739","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2262,"text":"Journal of Environmental Quality","active":true,"publicationSubtype":{"id":10}},"title":"Preliminary comparison of landscape pattern-normalized difference vegetation index (NDVI) relationships to central plains stream conditions","docAbstract":"We explored relationships of water quality parameters with landscape pattern metrics (LPMs), land use–land cover (LULC) proportions, and the advanced very high resolution radiometer (AVHRR) normalized difference vegetation index (NDVI) or NDVI-derived metrics. Stream sites (271) in Nebraska, Kansas, and Missouri were sampled for water quality parameters, the index of biotic integrity, and a habitat index in either 1994 or 1995. Although a combination of LPMs (interspersion and juxtaposition index, patch density, and percent forest) within Ozark Highlands watersheds explained >60% of the variation in levels of nitrite–nitrate nitrogen and conductivity, in most cases the LPMs were not significantly correlated with the stream data. Several problems using landscape pattern metrics were noted: small watersheds having only one or two patches, collinearity with LULC data, and counterintuitive or inconsistent results that resulted from basic differences in land use–land cover patterns among ecoregions or from other factors determining water quality. The amount of variation explained in water quality parameters using multiple regression models that combined LULC and LPMs was generally lower than that from NDVI or vegetation phenology metrics derived from time-series NDVI data. A comparison of LPMs and NDVI indicated that NDVI had greater promise for monitoring landscapes for stream conditions within the study area.
","language":"English","publisher":"American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America","doi":"10.2134/jeq2002.8460","usgsCitation":"Griffith, J.A., Martinko, E.A., Whistler, J.L., and Price, K.P., 2002, Preliminary comparison of landscape pattern-normalized difference vegetation index (NDVI) relationships to central plains stream conditions: Journal of Environmental Quality, v. 31, no. 3, p. 846-859, https://doi.org/10.2134/jeq2002.8460.","productDescription":"14 p.","startPage":"846","endPage":"859","numberOfPages":"14","costCenters":[{"id":222,"text":"Earth Resources Observation and Science (EROS) Center","active":true,"usgs":true}],"links":[{"id":232959,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Kansas, Missouri, Nebraska","otherGeospatial":"Central Plains","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -94.54833984375,\n 37.09023980307208\n ],\n [\n -92.48291015625,\n 38.13455657705411\n ],\n [\n -91.64794921875,\n 39.690280594818034\n ],\n [\n -91.58203125,\n 40.48038142908172\n ],\n [\n -95.69091796875,\n 40.58058466412761\n ],\n [\n -96.52587890625,\n 42.52069952914966\n ],\n [\n -100.48095703125,\n 42.97250158602597\n ],\n [\n -103.5791015625,\n 42.90816007196054\n ],\n [\n -103.6669921875,\n 41.60722821271717\n ],\n [\n -101.90917968749999,\n 41.178653972331674\n ],\n [\n -101.6015625,\n 38.95940879245423\n ],\n [\n -101.90917968749999,\n 37.19533058280065\n ],\n [\n -94.54833984375,\n 37.09023980307208\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"31","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a8359e4b0c8380cd7bef1","contributors":{"authors":[{"text":"Griffith, J. A.","contributorId":84118,"corporation":false,"usgs":true,"family":"Griffith","given":"J.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":402466,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Martinko, E. A.","contributorId":13784,"corporation":false,"usgs":true,"family":"Martinko","given":"E.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":402463,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Whistler, J. L.","contributorId":74171,"corporation":false,"usgs":true,"family":"Whistler","given":"J.","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":402465,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Price, K. P.","contributorId":16615,"corporation":false,"usgs":true,"family":"Price","given":"K.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":402464,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70024853,"text":"70024853 - 2002 - Empirical evidence for acceleration-dependent amplification factors","interactions":[],"lastModifiedDate":"2012-03-12T17:20:09","indexId":"70024853","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1135,"text":"Bulletin of the Seismological Society of America","onlineIssn":"1943-3573","printIssn":"0037-1106","active":true,"publicationSubtype":{"id":10}},"title":"Empirical evidence for acceleration-dependent amplification factors","docAbstract":"Site-specific amplification factors, Fa and Fv, used in current U.S. building codes decrease with increasing base acceleration level as implied by the Loma Prieta earthquake at 0.1g and extrapolated using numerical models and laboratory results. The Northridge earthquake recordings of 17 January 1994 and subsequent geotechnical data permit empirical estimates of amplification at base acceleration levels up to 0.5g. Distance measures and normalization procedures used to infer amplification ratios from soil-rock pairs in predetermined azimuth-distance bins significantly influence the dependence of amplification estimates on base acceleration. Factors inferred using a hypocentral distance norm do not show a statistically significant dependence on base acceleration. Factors inferred using norms implied by the attenuation functions of Abrahamson and Silva show a statistically significant decrease with increasing base acceleration. The decrease is statistically more significant for stiff clay and sandy soil (site class D) sites than for stiffer sites underlain by gravely soils and soft rock (site class C). The decrease in amplification with increasing base acceleration is more pronounced for the short-period amplification factor, Fa, than for the midperiod factor, Fv.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Bulletin of the Seismological Society of America","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1785/0120010170","issn":"00371106","usgsCitation":"Borcherdt, R., 2002, Empirical evidence for acceleration-dependent amplification factors: Bulletin of the Seismological Society of America, v. 92, no. 2, p. 761-782, https://doi.org/10.1785/0120010170.","startPage":"761","endPage":"782","numberOfPages":"22","costCenters":[],"links":[{"id":207811,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1785/0120010170"},{"id":233035,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"92","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a0909e4b0c8380cd51d87","contributors":{"authors":[{"text":"Borcherdt, R. D. 0000-0002-8668-0849","orcid":"https://orcid.org/0000-0002-8668-0849","contributorId":32165,"corporation":false,"usgs":true,"family":"Borcherdt","given":"R. D.","affiliations":[],"preferred":false,"id":402873,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70024396,"text":"70024396 - 2002 - Consistency of patterns in concentration‐discharge plots","interactions":[],"lastModifiedDate":"2018-11-06T13:49:42","indexId":"70024396","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3722,"text":"Water Resources Research","onlineIssn":"1944-7973","printIssn":"0043-1397","active":true,"publicationSubtype":{"id":10}},"title":"Consistency of patterns in concentration‐discharge plots","docAbstract":"Concentration‐discharge (c‐Q) plots have been used to infer how flow components such as event water, soil water, and groundwater mix to produce the observed episodic hydrochemical response of small catchments. Because c‐Q plots are based only on observed streamflow and solute concentration, their interpretation requires assumptions about the relative volume, hydrograph timing, and solute concentration of the streamflow end‐members. Evans and Davies [1998] present a taxonomy of c‐Q loops resulting from three‐component conservative mixing. Their analysis, based on a fixed template of end‐member hydrograph volume, timing, and concentration, suggests a unique relationship between c‐Q loop form and the rank order of end‐member concentrations. Many catchments exhibit variability in component contributions to storm flow in response to antecedent conditions or rainfall characteristics, but the effects of such variation on c‐Q relationships have not been studied systematically. Starting with a “baseline” condition similar to that assumed by Evans and Davies [1998], we use a simple computer model to characterize the variability in c‐Q plot patterns resulting from variation in end‐member volume, timing, and solute concentration. Variability in these three factors can result in more than one c‐Q loop shape for a given rank order of end‐member solute concentrations. The number of resulting hysteresis patterns and their relative frequency depends on the rank order of solute concentrations and on their separation in absolute value. In ambiguous cases the c‐Q loop shape is determined by the relative “prominence” of the event water versus soil water components. This “prominence” is broadly defined as a capacity to influence the total streamflow concentration and may result from a combination of end‐member volume, timing, or concentration. The modeling results indicate that plausible hydrological variability in field situations can confound the interpretation of c‐Q plots, even when fundamental end‐member mixing assumptions are satisfied.