The d'Entrecasteaux zone (DEZ) collides with the central New Hebrides island arc and consists of two subparallel ridges that strike east-west, stand 1–2 km above the surrounding oceanic plate, and subduct obliquely (15°) northward beneath the arc. Rocks dredged from the north ridge as well as reflections evident in multichannel seismic reflection data indicate that this ridge has a volcanic origin. Crystalline volcanic rocks are common along the lower flank of the ridge, but sedimentary, probably volcaniclastic, rock caps the ridge. Seismic reflection data collected over the lower arc slope reveal that mass wasting deposits locally make up most of the accretionary wedge. These deposits appear to form discrete bodies, suggesting that mass wasting occurred episodically. Large anticlines and thrust faults having large vertical separation are not readily evident where the colliding ridge intersects the arc slope; apparently, slope rocks have low strength so that mass wasting deposits formed instead of large-relief structures. Mass wasting is thought to occur as the accretionary wedge is uplifted in response to the northward oblique subduction of the north ridge. The toe of the north ridge flank marks an abrupt transition in the lithologies that make up the footwall of the interplate decollement. Footwall lithologies change from ocean basin to volcaniclastic ridge material, and this transition probably marks a discontinuity in friction along the decollement or in rock mechanical properties because north of the transition, thrust faults deform the accretionary wedge whereas south of the transition, steep reverse faults crosscut the wedge and pierce the north flank of the ridge. This piercement means that the decollement at least locally lies within the ridge and that ridge material exotic to the New Hebrides arc may be incorporated into the accretionary wedge.
The PLASM and Random Walk ground-water flow and contaminant transport models were used to assess the potential impact of various proposed regulatory compliance distances on landfill siting. Contaminant transport modeling was performed for 16 generalized geological sequences representative of hydrogeological conditions over an estimated 90 to 95 percent of Illinois. Results of this modeling indicate that about 50 percent of the state would be hydrogeologically suitable for landfilling of nonhazardous wastes if the compliance distance was 100 feet. With a compliance distance of 500 feet, about 55 percent of the state would be hydrogeologically suitable. This work demonstrates the utility of computer modeling in the development of regulations governing landfill siting.
Middle Eocene to middle Miocene mélange and broken formations are exposed in the coastal outcrops along the west side of the Olympic Peninsula, Washington. A petroleum geochemical assessment of these geologic units has included the investigation of biomarker compounds. A comparison was made of biomarkers in an oil sample from a middle Miocene reservoir penetrated in the Medina No. 1 well with biomarkers in extracts from two samples of middle Eocene Ozette mélange (one sample having a strong petroliferous odor, and the other sample lacking this characteristic odor). Distribution patterns of n-alkanes, tricyclic terpanes, pentacyclic triterpanes, steranes, and diasteranes are remarkably similar in the oil and rock extracts. Biomarker maturity parameters indicate higher maturity in the oil relative to the extracts. The presence of 17α(H)-23,28-bisnorlupane, 18α(H)- and 18β(H)-oleanane, and de-A-lupane and an odd-carbon-number dominance of the n-alkanes in the oil and extracts seems to tie the hydrocarbons to a common source that has a significant terrigenous component.
","language":"English","publisher":"Elsevier","doi":"10.1016/0009-2541(91)90066-Z","issn":"00092541","usgsCitation":"Kvenvolden, K.A., Hostettler, F.D., Rapp, J., and Snavely, P., 1991, Biomarkers in Tertiary mélange, western Olympic Peninsula, Washington, U.S.A.: Chemical Geology, v. 93, no. 1-2, p. 101-110, https://doi.org/10.1016/0009-2541(91)90066-Z.","productDescription":"10 p.","startPage":"101","endPage":"110","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[],"links":[{"id":223114,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":266074,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/0009-2541(91)90066-Z"}],"volume":"93","issue":"1-2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f188e4b0c8380cd4aca4","contributors":{"authors":[{"text":"Kvenvolden, Keith A. kkvenvolden@usgs.gov","contributorId":3384,"corporation":false,"usgs":true,"family":"Kvenvolden","given":"Keith","email":"kkvenvolden@usgs.gov","middleInitial":"A.","affiliations":[{"id":520,"text":"Pacific Coastal and Marine Science Center","active":true,"usgs":true}],"preferred":true,"id":373378,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hostettler, Frances D. fdhostet@usgs.gov","contributorId":3383,"corporation":false,"usgs":true,"family":"Hostettler","given":"Frances","email":"fdhostet@usgs.gov","middleInitial":"D.","affiliations":[],"preferred":true,"id":373379,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Rapp, John B.","contributorId":32028,"corporation":false,"usgs":true,"family":"Rapp","given":"John B.","affiliations":[],"preferred":false,"id":373377,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Snavely, Parke D. Jr.","contributorId":80328,"corporation":false,"usgs":true,"family":"Snavely","given":"Parke D.","suffix":"Jr.","affiliations":[],"preferred":false,"id":373376,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":5222588,"text":"5222588 - 1991 - Captive breeding and reintroduction of the endangered masked bobwhite","interactions":[],"lastModifiedDate":"2026-04-29T16:17:16.709146","indexId":"5222588","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3807,"text":"Zoo Biology","active":true,"publicationSubtype":{"id":10}},"title":"Captive breeding and reintroduction of the endangered masked bobwhite","docAbstract":"Efforts to restore the endangered masked bobwhite (Colinus virginianus ridgwayi) to its former range have required 1) habitat acquisition, restoration, and preservation; 2) captive propagation; and 3) reintroduction of captive-bred stock. In its role to recover the masked bobwhite, the Patuxent Wildlife Research Center (U.S. Fish and Wildlife Service) has refined captive breeding techniques; provided captive-produced stock for release; conducted field research on the distribution, limiting factors, and habitat characteristics of this species; and developed release methods. Techniques for the husbandry and captive management, breeding, artificial incubation and hatching of eggs, and rearing of young of the masked bobwhite have been developed. Successful reintroduction techniques for the masked bobwhite have included prerelease conditioning and/or cross-fostering of captive-reared masked bobwhite chicks to a wild-caught, related, vasectomized bobwhite species and their release to the wild as family units. In addition, the establishment by the U.S. Fish and Wildlife Service of the Buenos Aires National Wildlife Refuge in 1985 has further enhanced the potential for establishing a self-sustaining population of the masked bobwhite in the U.S. Through continued releases and active management of habitat, therefore, it is believed that the masked bobwhite can become permanently established at the refuge to ensure its continued survival in the wild.
","language":"English","publisher":"Wiley","doi":"10.1002/zoo.1430100602","usgsCitation":"Carpenter, J.W., Gabel, R.R., and Goodwin, J., 1991, Captive breeding and reintroduction of the endangered masked bobwhite: Zoo Biology, v. 10, no. 6, p. 439-449, https://doi.org/10.1002/zoo.1430100602.","productDescription":"11 p.","startPage":"439","endPage":"449","costCenters":[{"id":531,"text":"Patuxent Wildlife Research Center","active":true,"usgs":true}],"links":[{"id":194195,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"10","issue":"6","noUsgsAuthors":false,"publicationDate":"2005-05-13","publicationStatus":"PW","scienceBaseUri":"4f4e49e5e4b07f02db5e6d61","contributors":{"authors":[{"text":"Carpenter, J. W.","contributorId":81854,"corporation":false,"usgs":true,"family":"Carpenter","given":"J.","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":336619,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gabel, R. R.","contributorId":70500,"corporation":false,"usgs":true,"family":"Gabel","given":"R.","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":336618,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Goodwin, J.G.","contributorId":55919,"corporation":false,"usgs":true,"family":"Goodwin","given":"J.G.","affiliations":[],"preferred":false,"id":336617,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70016663,"text":"70016663 - 1991 - Low sulfur content in submarine lavas: An unreliable indicator of subaerial eruption","interactions":[],"lastModifiedDate":"2024-01-24T01:10:25.757251","indexId":"70016663","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1796,"text":"Geology","active":true,"publicationSubtype":{"id":10}},"title":"Low sulfur content in submarine lavas: An unreliable indicator of subaerial eruption","docAbstract":"Low S content (<250 ppm) has been used to identify subaerially erupted Hawaiian and Icelandic lavas. Large differences in S content of submarine-erupted lavas from different tectonic settings indicate that the behavior of S is complex. Variations in S abundance in undegassed, submarine-erupted lavas can result from different source compositions, different percentages of partial melting, and crystal fractionation. Low S concentrations in highly vesicular submarine lavas suggest that partial degassing can occur despite great hydrostatic pressure. These processes need to be evaluated before using S content as an indicator of eruption depth.
A vertically integrated two-dimensional lateral flow model of soil moisture has been developed. Derivation of the governing equation is based on a physical interpretation of hillslope processes. The lateral subsurface-flow model permits variability of precipitation and evapotranspiration, and allows arbitrary specification of soil-moisture retention properties. Variable slope, soil thickness, and saturation are all accommodated. The numerical solution method, a Crank-Nicolson, finite-difference, upstream-weighted scheme, is simple and robust. A small catchment in northeastern Kansas is the subject of an application of the lateral subsurface-flow model. Calibration of the model using observed discharge provides estimates of the active porosity (0.1 cm3/cm3) and of the saturated horizontal hydraulic conductivity (40 cm/hr). The latter figure is at least an order of magnitude greater than the vertical hydraulic conductivity associated with the silty clay loam soil matrix. The large value of hydraulic conductivity derived from the calibration is suggestive of macropore-dominated hillslope drainage. The corresponding value of active porosity agrees well with a published average value of the difference between total porosity and field capacity for a silty clay loam.
","language":"English","publisher":"Elsevier","doi":"10.1016/0309-1708(91)90012-D","usgsCitation":"Blain, C.A., and Milly, P., 1991, Development and application of a hillslope hydrologic model: Advances in Water Resources, v. 14, no. 4, p. 168-174, https://doi.org/10.1016/0309-1708(91)90012-D.","productDescription":"7 p.","startPage":"168","endPage":"174","numberOfPages":"7","costCenters":[],"links":[{"id":225181,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"14","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a0017e4b0c8380cd4f5ab","contributors":{"authors":[{"text":"Blain, C. A.","contributorId":45843,"corporation":false,"usgs":false,"family":"Blain","given":"C.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":374344,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Milly, P. C. D.","contributorId":100489,"corporation":false,"usgs":true,"family":"Milly","given":"P. C. D.","affiliations":[],"preferred":false,"id":374345,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70016434,"text":"70016434 - 1991 - Cenozoic prograding sequences of the Antarctic continental margin: a record of glacio-eustatic and tectonic events","interactions":[],"lastModifiedDate":"2019-06-11T09:47:47","indexId":"70016434","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","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":"Cenozoic prograding sequences of the Antarctic continental margin: a record of glacio-eustatic and tectonic events","docAbstract":"Sedimentary sections up to 6-14 km thick lie beneath many areas of the Antarctic continental margin. The upper parts of the sections contain up to 6 km of Cenozoic glacial and possibly non-glacial sequences that have prograded the continental shelf up to 85 km. We describe the Cenozoic sequences using two general categories based on their acoustic geometries. Type IA sequences, which account for most prograding of the Antarctic continental shelf, have complex sigmoidal geometries and some acoustic characteristics atypical of low-latitude margins, such as troughs and mounds lying parallel and normal to the shelf edge and high velocities (2.0-2.6 km/s) for flat layers within 150 m of the seafloor. Type IIA sequences, which principally aggrade the paleoshelf, lie beneath type IA sequences and have mostly simple geometries and gently dipping reflections. The prograding sequences are commonly located near the seaward edges of major Mesozoic and older margin structures. Relatively rapid Cenozoic subsidence has occurred due to the probable rifting in the Ross Sea, thermal subsidence in the Antarctic Peninsula, and isostatic crustal flexure in Wilkes Land. In Prydz Bay and the Weddell Sea, prograding sequences cover Mesozoic basins that have undergone little apparent Cenozoic tectonism. Grounded ice sheets are viewed by us, and others, as the principal mechanism for depositing the Antarctic prograding sequences. During the initial advance of grounded ice the continental shelf is flexurally overdeepened, the inner shelf is heavily eroded, and gently dipping glacial strata are deposited on the shelf (i.e type IIA sequences). The overdeepened shelf profile is preserved (a) during glacial times, by grounded ice sheets episodically crossing the shelf, eroding sediments from onshore and inner shelf areas, and depositing sediments at the front of the ice sheet as outer shelf topset-banks and continental slope foreset-aprons (i.e. type IA sequences), and (b) during interglacial times, like today, by little or no clastic sedimentation on the continental shelf other than beneath retreated ice shelves lying far from the continental sheld edge. Ice streams carve broad depressions across the shelf and carry abundant basal sediments directly to the continental shelf edge, thereby creating troughmouth fans and sheet-like prograding sequences (i.e. type IA sequences). Numerous acoustic unconformities and multiple overcompacted layers within the prograding sequences suggest major fluctuations of the Antarctic Ice Sheet. The available drilling and seismic interpretations provide the following history: (1) Cenozoic ice sheets have existed in places near the continental shelf since middle to late Eocene time. (2) A grounded Antarctic ice sheet first expanded to the continental shelf edge, with probable overdeepening of the outer shelf, in late Eucene to early Oligocene time in Prydz Bay, possibly in early Miocene time in the Ross Sea, and at least by middle Miocene time in the Weddell Sea. (3) The relative amounts of shelf prograding and inferred ice-volume variations (and related sea-level changes) have increased since middle to late Miocene time in the eastern Ross Sea, Prydz Bay, and possibly Weddell Sea. Our analysis is preliminary. Further acoustic surveys and scientific drilling are needed to resolve the proximal Antarctic record of glacio-eustatic, climatic, and tectonic events recorded by the prograding sequences.
","language":"English","publisher":"Elsevier","doi":"10.1016/0025-3227(91)90008-R","issn":"00253227","usgsCitation":"Cooper, A.K., Barrett, P.J., Hinz, K., Traube, V., Letichenkov, G., and Stagg, H., 1991, Cenozoic prograding sequences of the Antarctic continental margin: a record of glacio-eustatic and tectonic events: Marine Geology, v. 102, no. 1-4, p. 175-213, https://doi.org/10.1016/0025-3227(91)90008-R.","productDescription":"39 p.","startPage":"175","endPage":"213","numberOfPages":"39","costCenters":[],"links":[{"id":223021,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"102","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f3e6e4b0c8380cd4ba0f","contributors":{"authors":[{"text":"Cooper, A. K.","contributorId":50149,"corporation":false,"usgs":true,"family":"Cooper","given":"A.","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":373500,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Barrett, P. J.","contributorId":96347,"corporation":false,"usgs":false,"family":"Barrett","given":"P.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":373503,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hinz, K.","contributorId":83273,"corporation":false,"usgs":true,"family":"Hinz","given":"K.","email":"","affiliations":[],"preferred":false,"id":373502,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Traube, V.","contributorId":29134,"corporation":false,"usgs":true,"family":"Traube","given":"V.","email":"","affiliations":[],"preferred":false,"id":373499,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Letichenkov, G.","contributorId":61963,"corporation":false,"usgs":true,"family":"Letichenkov","given":"G.","email":"","affiliations":[],"preferred":false,"id":373501,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Stagg, H.M.J.","contributorId":7843,"corporation":false,"usgs":true,"family":"Stagg","given":"H.M.J.","email":"","affiliations":[],"preferred":false,"id":373498,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70016487,"text":"70016487 - 1991 - Wading measurements of vertical velocity profiles","interactions":[],"lastModifiedDate":"2024-02-05T12:42:53.013058","indexId":"70016487","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1801,"text":"Geomorphology","active":true,"publicationSubtype":{"id":10}},"title":"Wading measurements of vertical velocity profiles","docAbstract":"Increasingly, there is a recognized need to enhance research of hydraulic, geomorphic and sediment-transport processes in rivers. This research often includes studies of the velocity distribution in rivers. This paper describes the use of the topsetting wading rod and a table and an analytical expression to more easily obtain vertical velocity profiles in rivers.
Three fulvic acids, two of which have been well studied by a number of other groups (Armadale and Suwannee river fulvic acids) have been examined by high resolution solid-state 13C-NMR techniques to delineate the effect of absorbed water. Two main effects of absorbed water were observed: (1) changes in spin lattice relaxation times in the rotating frame and cross polarization times and (2) total loss of signal so that some fulvic acid is effectively in solution. These results suggest that discrepancies in the literature concerning observed relative signal intensities from different structural groups are due to absorbed water and emphasize the necessity for proper precautionary drying before spectroscopic analysis.
","language":"English","publisher":"Elsevier","doi":"10.1016/0146-6380(91)90092-X","usgsCitation":"Hatcher, P.G., and Wilson, M.A., 1991, The effect of sample hydration on 13C CPMAS NMR spectra of fulvic acids: Organic Geochemistry, v. 17, no. 3, p. 293-299, https://doi.org/10.1016/0146-6380(91)90092-X.","productDescription":"7 p.","startPage":"293","endPage":"299","costCenters":[],"links":[{"id":223797,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"17","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bab4be4b08c986b322d4a","contributors":{"authors":[{"text":"Hatcher, Patrick G.","contributorId":93625,"corporation":false,"usgs":true,"family":"Hatcher","given":"Patrick","email":"","middleInitial":"G.","affiliations":[],"preferred":false,"id":369899,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wilson, Michael A.","contributorId":66335,"corporation":false,"usgs":true,"family":"Wilson","given":"Michael","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":369900,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70016600,"text":"70016600 - 1991 - Jasper Seamount: Seven million years of volcanism","interactions":[],"lastModifiedDate":"2024-01-24T01:12:01.153452","indexId":"70016600","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1796,"text":"Geology","active":true,"publicationSubtype":{"id":10}},"title":"Jasper Seamount: Seven million years of volcanism","docAbstract":"Jasper Seamount is a young, mid-sized (690 km3) oceanic intraplate volcano located about 500 km west-southwest of San Diego, California. Reliable 40Ar/39Ar age data were obtained for several milligram-sized samples of 4 to 10 Ma plagioclase by using a defocused laser beam to clean the samples before fusion. Gee and Staudigel suggested that Jasper Seamount consists of a transitional to tholeiitic shield volcano formed by flank transitional series lavas, overlain by flank alkalic series lavas and summit alkalic series lavas. Twenty-nine individual 40Ar/39Ar laser fusion analyses on nine samples confirm the stratigraphy:10.3-10.0 Ma for the flank transitional series, 8.7-7.5 Ma for the flank alkalic series, and 4.8-4.1 Ma for the summit alkalic series. The alkalinity of the lavas clearly increases with time, and there appear to be 1 to 3 m.y. hiatuses between each series. The age data are consistent with the complex magnetic anomaly of Jasper; however, the dominant reversed polarity inferred from the anomaly suggests that most of the seamount formed at ca. 11 Ma, prior to the onset of Chron C5N. The duration of volcanism of Jasper Seamount is slightly longer than the duration of volcanism at Hawaiian volcanoes, suggesting that individual age data from seamounts may constrain the age of a seamount only to within about 7 m.y. unless the stage of volcanism can be unambiguously determined. Extrapolating from the results of our study, similar precision in age determinations should be possible on 50 mg of 1 Ma plagioclase from mid-ocean ridge basalt, opening new possibilities in the geochronology of young, low-potassium volcanic rocks.
The pattern of historical ground deformation, seismicity, and crustal structure near Medicine Lake volcano illustrates a close relation between magmatism and tectonism near the margin of the Cascade volcanic chain and the Basin and Range tectonic province. Between leveling surveys in 1954 and 1989 the summit of Medicine Lake volcano subsided 389±43 mm with respect to a reference bench mark 40 km to the southwest (average rate = 11.1±1.2 mm/yr). A smaller survey across the summit caldera in 1988 suggests that the subsidence rate was 15–28 mm/yr during 1988–1989. Swarms of shallow earthquakes (M ≤ 4.6) occurred in the region during August 1978, January–February 1981, and September 1988. Except for the 1988 swarm, which occurred beneath Medicine Lake caldera, most historical earthquakes were located at least 25 km from the summit. The spatial relation between subsidence and seismicity indicates (1) radially symmetric downwarping of the volcano's summit and flanks centered near the caldera and (2) downfaulting of the entire edifice along regional faults located 25–30 km from the summit. We propose that contemporary subsidence, seismicity, and faulting are caused by (1) loading of the crust by more than 600 km3 of erupted products plus a large volume of mafic intrusives; (2) east-west extension in the western Basin and Range province; and, to a lesser extent, (3) crystallization or withdrawal of magma beneath the volcano. Thermal weakening of the subvolcanic crust by mafic intrusions facilitates subsidence and influences the distribution of earthquakes. Subsidence occurs mainly by aseismic creep within 25 km of the summit, where the crust has been heated and weakened by intrusions, and by normal faulting during episodic earthquake swarms in surrounding, cooler terrain.
No abstract available.
","language":"English","publisher":"American Chemical Society","doi":"10.1021/es00024a016","issn":"0013936X","usgsCitation":"Bales, R., Hinkle, S., Kroeger, T., Stocking, K., and Gerba, C., 1991, Bacteriophage adsorption during transport through porous media: Chemical perturbations and reversibility: Environmental Science & Technology, v. 25, no. 12, p. 2088-2095, https://doi.org/10.1021/es00024a016.","productDescription":"8 p.","startPage":"2088","endPage":"2095","costCenters":[],"links":[{"id":223901,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"25","issue":"12","noUsgsAuthors":false,"publicationDate":"2002-05-01","publicationStatus":"PW","scienceBaseUri":"5059efa7e4b0c8380cd4a398","contributors":{"authors":[{"text":"Bales, R.C.","contributorId":10379,"corporation":false,"usgs":true,"family":"Bales","given":"R.C.","email":"","affiliations":[],"preferred":false,"id":369596,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hinkle, S.R.","contributorId":74778,"corporation":false,"usgs":true,"family":"Hinkle","given":"S.R.","email":"","affiliations":[],"preferred":false,"id":369599,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kroeger, T.W.","contributorId":31262,"corporation":false,"usgs":true,"family":"Kroeger","given":"T.W.","email":"","affiliations":[],"preferred":false,"id":369597,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Stocking, K.","contributorId":101518,"corporation":false,"usgs":true,"family":"Stocking","given":"K.","email":"","affiliations":[],"preferred":false,"id":369600,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Gerba, C.P.","contributorId":40423,"corporation":false,"usgs":true,"family":"Gerba","given":"C.P.","affiliations":[],"preferred":false,"id":369598,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70014914,"text":"70014914 - 1991 - Offshore and onshore liquefaction at Moss Landing spit, central California, - result of the October 17, 1989, Loma Prieta earthquake","interactions":[],"lastModifiedDate":"2024-01-24T01:17:56.539493","indexId":"70014914","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1796,"text":"Geology","active":true,"publicationSubtype":{"id":10}},"title":"Offshore and onshore liquefaction at Moss Landing spit, central California, - result of the October 17, 1989, Loma Prieta earthquake","docAbstract":"As a result of the October 17, 1989, Loma Prieta (Santa Cruz Mountains, California) earthquake, liquefaction of the fluvial, estuarine, eolian, and beach sediments under a sand spit destroyed the Moss Landing Marine Laboratories and damaged other structures and utilities. Initial studies suggested that the liquefaction was a local phenomenon. More detailed offshore investigations, however, indicate that it occurred over a large area (max. 8 km2) during or shortly after the earthquake with movement of unconsolidated sediment toward and into the head of Monterey submarine canyon. This conclusion is supported by side-scan sonographs, high-resolution seismic-reflection and bathymetric profiles, onshore and sea-floor photographs, and underwater video tapes. Many distinct lobate features were identified on the shallow shelf. These features almost certainly were the result of the October 17 earthquake; they were subsequently destroyed by winter storms. In addition, fresh slump scars and recently dislodged mud debris were found on the upper, southern wall of Monterey submarine canyon.
Random tilting of a single paleomagnetic vector produces a distribution of vectors which is not rotationally symmetric about the original vector and therefore not Fisherian. Monte Carlo simulations were performed on two types of vector distributions: (1) distributions of vectors formed by perturbing a single original vector with a Fisher distribution of bedding poles (each defining a tilt correction) and (2) standard Fisher distributions. These simulations demonstrate that inclinations of vectors drawn from both distributions are biased toward shallow inclinations. There is a greater likelihood of statistically “drawing” a vector shallower than the true mean vector than of drawing one that is steeper. The estimated probability increases as a function of angular dispersion and inclination of the true mean vector. Consequently, the interpretation of inclination-only data from either type of distribution is not straightforward, especially when the expected paleolatitude is greater than about 50°. Because of the symmetry of the two distributions, declinations of vectors in each distribution are unbiased. The Fisher mean direction of the distribution of vectors formed by perturbing a single vector with random undetected tilts is biased toward shallow inclinations, but this bias is insignificant for angular dispersions of bedding poles less than 20°. This observation implies that the mean pole calculated from a large set of paleomagnetic directions obtained for coeval rocks over a region will be effectively unbiased by random undetected tilts of those rocks provided the angular dispersion of the undetected tilts is less than about 20°. However, the bias of the mean can be significant for large (>20°) angular dispersion of tilts. The amount of bias of the mean direction maximizes at about 10°–12° in mid-latitude regions but is usually less than 8°. Consequently, large (>12°) inclination discordances are probably not the result of random undetected tilts, even if the angular dispersion of the tilts exceeds 20°.