Several recent models of crustal evolution are based on the belief that the thickness of the continental crust is proportional to its age, with ancient crust being the thickest. A worldwide review of seismic structure contradicts this belief and falsifies these models, at least for the Archean. Proterozoic crust has a thickness of 40–55 km and a substantial high‐velocity (>7 km/s) layer at its base, while Archean crust is only 27–40 km thick (except at the site of younger rifts and collisional boundaries) and lacks the basal high‐velocity layer. Seismology also provides evidence that the lithosphere is thickest beneath Archean cratons, while diamond ages show that this lithospheric keel must have already existed in the Archean. Geochemical data also indicate significant differences between Archean and Proterozoic lithosphere. Major and trace element studies of sediments show a change in upper crustal composition between the Archean and Proterozoic. Archean rocks are depleted in Si and K and enriched in Na, Ca, and Mg. There is also a marked change in the Eu/Eu* ratio. Mantle xenoliths and continental flood basalts show that the mantle lithosphere beneath Archean crust is ultradepleted in FeO compared to that beneath post‐Archean crust. The secular change in the crust‐forming process is attributed to a decline in mantle temperature, leading to a change in the composition of the lithospheric mantle. The higher temperature of the Archean mantle led to the eruption of komatiitic lavas, producing a refractory lithospheric mantle which is ultradepleted in FeO and volatiles. The resultant lithospheric keel is intrinsically less dense than the surrounding mantle and thus not susceptible to delamination. It was sufficiently thick and cool for diamonds to form during the Archean. In contrast, Proterozoic crust developed above fertile mantle. The eruption of continental flood basalts and underplating of basaltic sills is attributed to subsequent heating and partial melting of the lithospheric mantle. Consequently, Proterozoic crust is thickened and has a high‐velocity basal layer.
The Fairbanks North seismic refraction/ wide-angle reflection profile, collected by the U.S. Geological Survey Trans-Alaska Crustal Transect (TACT) project in 1987, crosses the complex region between the Yukon-Tanana and Ruby terranes in interior Alaska. This region is occupied by numerous small terranes elongated in a northeast-southwest direction. These seismic data reveal a crustal velocity structure that is divided into three upper-crustal and at least two middle- to lower-crustal domains. The upper-crustal domains are delineated by two steeply dipping low-velocity anomalies that are interpreted as signatures of the Victoria Creek fault, and the Beaver Creek fault or a fault buried by the Beaver Creek fault. This tripartite upper crust extends to 8-10 km depth where a subhorizontal interface undercuts the northern and central domains. Beneath the northern domain, this interface is interpreted as the southeastwardly dipping boundary between the Tozina and Ruby terranes. The continuation of this interface beneath the central domain suggests that it may represent the detachment or basal thrust for thin-skinned tectonic amalgamation of the terranes caught between the Yukon-Tanana and Ruby terranes. The lower crust and Moho reflection exhibit differences from north to south that define at least two lower-crustal domains, interpreted as the Yukon-Tanana and Ruby terranes. Finally, the crustal thickness along the profile is nearly uniform and ranges from 31 to 34 km. Our data suggest that after initial thin-skinned amalgamation of the various terranes, this region experienced thick-skinned tectonic reorganization via strike-slip faulting. This interpretation supports a model in which at least one strand of the Tintina fault exists in this important region of Alaska.
","language":"English","publisher":"Geological Society of America ","doi":"10.1130/0016-7606(1994)106<0981:CVSOTN>2.3.CO;2","usgsCitation":"Beaudoin, B.C., Fuis, G.S., Lutter, W.J., Mooney, W.D., and Moore, T.E., 1994, Crustal velocity structure of the northern Yukon-Tanana upland, central Alaska: Results from TACT refraction/wide-angle reflection data: Bulletin, v. 106, no. 8, p. 981-1001, https://doi.org/10.1130/0016-7606(1994)106<0981:CVSOTN>2.3.CO;2.","productDescription":"21 p. ","startPage":"981","endPage":"1001","costCenters":[{"id":237,"text":"Earthquake Science Center","active":true,"usgs":true}],"links":[{"id":339003,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alaska","otherGeospatial":"Yukon-Tanana upland","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -160.6640625,\n 61.71070595883174\n ],\n [\n -141.2841796875,\n 61.71070595883174\n ],\n [\n -141.2841796875,\n 68.80004113882613\n ],\n [\n -160.6640625,\n 68.80004113882613\n ],\n [\n -160.6640625,\n 61.71070595883174\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"106","issue":"8","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58e35f8fe4b09da67997ece8","contributors":{"authors":[{"text":"Beaudoin, Bruce C.","contributorId":58140,"corporation":false,"usgs":true,"family":"Beaudoin","given":"Bruce","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":687957,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Fuis, Gary S. 0000-0002-3078-1544 fuis@usgs.gov","orcid":"https://orcid.org/0000-0002-3078-1544","contributorId":2639,"corporation":false,"usgs":true,"family":"Fuis","given":"Gary","email":"fuis@usgs.gov","middleInitial":"S.","affiliations":[{"id":237,"text":"Earthquake Science Center","active":true,"usgs":true}],"preferred":true,"id":687958,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Lutter, William J.","contributorId":74366,"corporation":false,"usgs":true,"family":"Lutter","given":"William","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":687959,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Mooney, Walter D. 0000-0002-5310-3631 mooney@usgs.gov","orcid":"https://orcid.org/0000-0002-5310-3631","contributorId":3194,"corporation":false,"usgs":true,"family":"Mooney","given":"Walter","email":"mooney@usgs.gov","middleInitial":"D.","affiliations":[{"id":237,"text":"Earthquake Science Center","active":true,"usgs":true}],"preferred":true,"id":687960,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Moore, Thomas E. 0000-0002-0878-0457 tmoore@usgs.gov","orcid":"https://orcid.org/0000-0002-0878-0457","contributorId":1033,"corporation":false,"usgs":true,"family":"Moore","given":"Thomas","email":"tmoore@usgs.gov","middleInitial":"E.","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"preferred":false,"id":687961,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70186949,"text":"70186949 - 1994 - An image of the Columbia Plateau from inversion of high‐resolution seismic data ","interactions":[],"lastModifiedDate":"2017-04-14T15:41:24","indexId":"70186949","displayToPublicDate":"1994-08-01T00:00:00","publicationYear":"1994","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1808,"text":"Geophysics","active":true,"publicationSubtype":{"id":10}},"title":"An image of the Columbia Plateau from inversion of high‐resolution seismic data ","docAbstract":"We use a method of traveltime inversion of high‐resolution seismic data to provide the first reliable images of internal details of the Columbia River Basalt Group (CRBG), the subsurface basalt/sediment interface, and the deeper sediment/basement interface. Velocity structure within the basalts, delineated on the order of 1 km horizontally and 0.2 km vertically, is constrained to within ±0.1 km/s for most of the seismic profile. Over 5000 observed traveltimes fit our model with an rms error of 0.018 s. The maximum depth of penetration of the basalt diving waves (truncated by underlying low‐velocity sediments) provides a reliable estimate of the depth to the base of the basalt, which agrees with well‐log measurements to within 0.05 km (165 ft). We use image blurring, calculated from the resolution matrix, to estimate the aspect ratio of imaged velocity anomaly widths to true widths for velocity features within the basalt. From our calculations of image blurring, we interpret low velocity zones (LVZ) within the basalts at Boylston Mountain and the Whiskey Dick anticline to have widths of 4.5 and 3 km, respectively, within the upper 1.5 km of the model. At greater depth, the widths of these imaged LVZs thin to approximately 2 km or less. We interpret these linear, subparallel, low‐velocity zones imaged adjacent to anticlines of the Yakima Fold Belt to be brecciated fault zones. These fault zones dip to the south at angles between 15 to 45 degrees.
A pure mode II (in-plane) shear crack cannot propagate spontaneously at a speed between the Rayleigh and S-wave speeds, but a three-dimensional (3D) or two-dimensional (2D) mixed-mode shear crack can propagate in this range, being driven by the mode III (antiplane) component. Two different analytic solutions have been proposed for the mode II component in this case. The first is the solution valid for crack speed less than the Rayleigh speed. When applied above the Rayleigh speed, it predicts a negative stress intensity factor, which implies that energy is generated at the crack tip. Burridge proposed a second solution, which is continuous at the crack tip, but has a singularity in slip velocity at the Rayleigh wave. Spontaneous propagation of a mixed-mode rupture has been calculated with a slip-weakening friction law, in which the slip velocity vector is colinear with the total traction vector. Spontaneous trans-Rayleigh rupture speed has been found. The solution depends on the absolute stress level. The solution for the in-plane component appears to be a superposition of smeared-out versions of the two analytic solutions. The proportion of the first solution increases with increasing absolute stress. The amplitude of the negative in-plane traction pulse is less than the absolute final sliding traction, so that total in-plane traction does not reverse. The azimuth of the slip velocity vector varies rapidly between the onset of slip and the arrival of the Rayleigh wave. The variation is larger at smaller absolute stress.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840041184","usgsCitation":"Andrews, D., 1994, Dynamic growth of mixed-mode shear cracks: Bulletin of the Seismological Society of America, v. 84, no. 4, p. 1184-1198, https://doi.org/10.1785/BSSA0840041184.","productDescription":"15 p.","startPage":"1184","endPage":"1198","costCenters":[],"links":[{"id":338962,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"84","issue":"4","noUsgsAuthors":false,"publicationDate":"1994-08-01","publicationStatus":"PW","scienceBaseUri":"58df6ac9e4b02ff32c6aea7d","contributors":{"authors":[{"text":"Andrews, D.J.","contributorId":7416,"corporation":false,"usgs":true,"family":"Andrews","given":"D.J.","email":"","affiliations":[],"preferred":false,"id":687859,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70243625,"text":"70243625 - 1994 - The seismic velocity structure of the Newfoundland Appalachian orogen","interactions":[],"lastModifiedDate":"2023-05-15T18:57:49.243083","indexId":"70243625","displayToPublicDate":"1994-07-10T13:49:53","publicationYear":"1994","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":"The seismic velocity structure of the Newfoundland Appalachian orogen","docAbstract":"The deep structure of the Newfoundland Appalachian orogen is investigated by analyses of three intersecting seismic refraction/wide-angle reflection profiles which traverse the Gander and Dunnage zones or central mobile belt of Newfoundland. A simultaneous travel time inversion for velocity and interface was applied to the in-line seismic refraction/wide-angle reflection data and constrained by synthetic amplitude models. The results of the modeling procedure show a subhorizontally layered crust with upper crustal velocities ranging from 5.4 to 6.2 km/s, a midcrustal velocity of 6.25–6.35 km/s, and a lower crustal velocity of 6.7±0.2 km/s. The top of the lower crust is marked by a series of prominent reflections between 18 and 23 km depth which suggest a complex layered velocity interface. Strong laterally coherent Moho reflections indicate a sharp crust-mantle transition at 35 ± 3 km. The uppermost mantle has a velocity of 8.0±0.2 km/s, and a reflecting horizon at 55 km depth suggests an increase to velocities approaching 8.5 km/s. Normal moveout corrections applied to fan profiles provide constraining evidence for the reflecting horizon at the top of the lower crust and laterally continuous Moho reflections at 11–12 s two-way travel time. Comparisons with a coincident deep seismic reflection profile show that the refraction and reflection Mohos match to better than 2–3 km. Bulk Poisson's ratios of 0.23–0.24 for the whole crust calculated from PmP/SmS travel times suggest a crust dominated by quartzofeldspathic lithologies and a notable absence of voluminous mafic additions to the lower crust. The absence of a deep crustal root, coupled with the bulk intermediate composition inferred for the lower crust from the seismic refraction/wide-angle data, implies that the crust beneath central Newfoundland has undergone multiple periods of reactivation and equilibration following successive orogenic episodes.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/94JB00653","usgsCitation":"Hughes, S., Hall, J., and Luetgert, J.H., 1994, The seismic velocity structure of the Newfoundland Appalachian orogen: Journal of Geophysical Research B: Solid Earth, v. 99, no. B7, p. 13633-13653, https://doi.org/10.1029/94JB00653.","productDescription":"21 p.","startPage":"13633","endPage":"13653","costCenters":[],"links":[{"id":417059,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Canada","state":"Newfoundland and Labrador","otherGeospatial":"Newfoundland","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -59.51136472850111,\n 47.94424995364702\n ],\n [\n -59.28280402686646,\n 47.48176244084547\n ],\n [\n -58.4484272552985,\n 47.56080806252484\n ],\n [\n -58.01483066533466,\n 47.57615588023074\n ],\n [\n -56.77954428954459,\n 47.448642912284186\n ],\n [\n -56.44245661843681,\n 47.50113073504082\n ],\n [\n -55.981104636466455,\n 47.301139958521134\n ],\n [\n -56.51192039799395,\n 47.01202484256643\n ],\n [\n -55.88085259871312,\n 46.73279968306559\n ],\n [\n -55.17807258771961,\n 46.862976891245665\n ],\n [\n -54.94294180551984,\n 47.19637476883719\n ],\n [\n -54.13521325973504,\n 47.27341726035215\n ],\n [\n -54.36592321899582,\n 46.810042626940316\n ],\n [\n -54.08287841020558,\n 46.70270265369035\n ],\n [\n -53.78171147985245,\n 46.944824670677036\n ],\n [\n -53.80822428375262,\n 46.74834834234139\n ],\n [\n -53.66037155212918,\n 46.51217734610435\n ],\n [\n -53.32131889211044,\n 46.55401792369224\n ],\n [\n -52.96969039126742,\n 46.51699128295064\n ],\n [\n -52.58399632312404,\n 47.5874271069988\n ],\n [\n -52.87627537009867,\n 48.05867502731806\n ],\n [\n -52.932382924273554,\n 48.59509857770249\n ],\n [\n -53.09081562391597,\n 48.69887819098352\n ],\n [\n -53.28054527302929,\n 48.61835796740991\n ],\n [\n -53.5586478131508,\n 48.68184034522139\n ],\n [\n -53.556402795297174,\n 48.94275022355632\n ],\n [\n -53.31266013430883,\n 49.27246433411227\n ],\n [\n -53.91706783822342,\n 49.5292907140572\n ],\n [\n -54.06392997321875,\n 49.84855147114237\n ],\n [\n -55.141139526916874,\n 49.58770727453668\n ],\n [\n -55.7907309881235,\n 49.70495883436678\n ],\n [\n -55.34629925235254,\n 49.90564841237418\n ],\n [\n -55.66966463139961,\n 50.31206345811336\n ],\n [\n -56.18116647038855,\n 50.24062486226876\n ],\n [\n -56.7783106893056,\n 49.78770909374788\n ],\n [\n -56.573643320697016,\n 50.04735138311631\n ],\n [\n -56.02217014273353,\n 50.47886652105859\n ],\n [\n -55.39719762497164,\n 50.723285095974575\n ],\n [\n -55.42026512430519,\n 51.38149796080947\n ],\n [\n -55.18890290678226,\n 52.13119994630222\n ],\n [\n -55.91678540299182,\n 51.68404745349517\n ],\n [\n -56.74518500572938,\n 51.44603069666897\n ],\n [\n -57.12935780855858,\n 51.08432238433181\n ],\n [\n -57.55656676197822,\n 50.57023985309144\n ],\n [\n -58.082960109775996,\n 49.62235441310665\n ],\n [\n -58.70826008258848,\n 48.78212110092642\n ],\n [\n -59.27734353568438,\n 48.59974432741211\n ],\n [\n -59.3671384025036,\n 48.39208367299375\n ],\n [\n -58.53560208143395,\n 48.48119870438893\n ],\n [\n -59.51136472850111,\n 47.94424995364702\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"99","issue":"B7","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","contributors":{"authors":[{"text":"Hughes, Stephen","contributorId":31406,"corporation":false,"usgs":true,"family":"Hughes","given":"Stephen","email":"","affiliations":[],"preferred":false,"id":872653,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hall, Jeremy","contributorId":305398,"corporation":false,"usgs":false,"family":"Hall","given":"Jeremy","email":"","affiliations":[],"preferred":false,"id":872654,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Luetgert, James H. luetgert@usgs.gov","contributorId":4203,"corporation":false,"usgs":true,"family":"Luetgert","given":"James","email":"luetgert@usgs.gov","middleInitial":"H.","affiliations":[],"preferred":true,"id":872655,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70243967,"text":"70243967 - 1994 - Diagenesis of diatomite from the Kolubara Coal Basin, Baroševac, Serbia","interactions":[],"lastModifiedDate":"2023-05-26T13:15:37.398894","indexId":"70243967","displayToPublicDate":"1994-07-01T07:53:33","publicationYear":"1994","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1782,"text":"Geological Journal","active":true,"publicationSubtype":{"id":10}},"title":"Diagenesis of diatomite from the Kolubara Coal Basin, Baroševac, Serbia","docAbstract":"Diatomite associated with the Kolubara Coal Basin was studied to better understand early stage silica diagenesis of shallow water deposits. The Kolubara Basin consists of Neogene siliciclastic rocks, diatomite, marlstone and rare carbonates. Palaeozoic metamorphic and Mesozoic sedimentary and igneous basement rocks are transgressively overlain by Upper Miocene sandstone, siltstone, shale and mudstone. This Upper Miocene section is transgressively overlain by the Pontian section, which contains diatomite and coal beds.
White and grey diatomite forms beds 0.7-2.2 m thick that are continuous over an area of about 2 km2. Siliceous rocks vary in composition from diatomite (81-89 per cent SiO2) to diatom-bearing shale (58-60 per cent SiO2). Siliceous deposits are laminated in places, with the laminae defined by variations in clay minerals, organic matter and diatoms. Diatomite shows only incipient diagenesis characterized by the fragmentation of diatom frustules, the minor to moderate corrosion of frustules and the formation of minor amounts of opal-A' (X-ray amorphous inorganic opal) cement. The low degree of diagenesis results from the young age of the deposits, low burial temperatures and possibly also from the presence of abundant organic matter and the dissolution of kaolinite. The presence of only weak diagenesis is also reflected by the characteristically poor consolidation of the rocks and low rank of the associated coal.
","language":"English","publisher":"Wiley","doi":"10.1002/gj.3350290303","usgsCitation":"Obradovic, J., Hein, J.R., and Djurdjevic, J., 1994, Diagenesis of diatomite from the Kolubara Coal Basin, Baroševac, Serbia: Geological Journal, v. 29, no. 3, p. 209-217, https://doi.org/10.1002/gj.3350290303.","productDescription":"9 p.","startPage":"209","endPage":"217","costCenters":[],"links":[{"id":417493,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Serbia","city":"Baroševac","otherGeospatial":"Kolubara Coal Basin","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n 20.3644717814619,\n 44.4003764845005\n ],\n [\n 20.3644717814619,\n 44.3892567423822\n ],\n [\n 20.403573410052047,\n 44.3892567423822\n ],\n [\n 20.403573410052047,\n 44.4003764845005\n ],\n [\n 20.3644717814619,\n 44.4003764845005\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"29","issue":"3","noUsgsAuthors":false,"publicationDate":"2007-04-30","publicationStatus":"PW","contributors":{"authors":[{"text":"Obradovic, J.","contributorId":305829,"corporation":false,"usgs":false,"family":"Obradovic","given":"J.","email":"","affiliations":[],"preferred":false,"id":873951,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hein, James R. 0000-0002-5321-899X jhein@usgs.gov","orcid":"https://orcid.org/0000-0002-5321-899X","contributorId":140835,"corporation":false,"usgs":true,"family":"Hein","given":"James","email":"jhein@usgs.gov","middleInitial":"R.","affiliations":[{"id":520,"text":"Pacific Coastal and Marine Science Center","active":true,"usgs":true}],"preferred":true,"id":873952,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Djurdjevic, J.","contributorId":305830,"corporation":false,"usgs":false,"family":"Djurdjevic","given":"J.","email":"","affiliations":[],"preferred":false,"id":873953,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70187191,"text":"70187191 - 1994 - Climate, soil water storage, and the average annual water balance","interactions":[],"lastModifiedDate":"2018-03-08T10:06:28","indexId":"70187191","displayToPublicDate":"1994-07-01T00:00:00","publicationYear":"1994","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":"Climate, soil water storage, and the average annual water balance","docAbstract":"This paper describes the development and testing of the hypothesis that the long-term water balance is determined only by the local interaction of fluctuating water supply (precipitation) and demand (potential evapotranspiration), mediated by water storage in the soil. Adoption of this hypothesis, together with idealized representations of relevant input variabilities in time and space, yields a simple model of the water balance of a finite area having a uniform climate. The partitioning of average annual precipitation into evapotranspiration and runoff depends on seven dimensionless numbers: the ratio of average annual potential evapotranspiration to average annual precipitation (index of dryness); the ratio of the spatial average plant-available water-holding capacity of the soil to the annual average precipitation amount; the mean number of precipitation events per year; the shape parameter of the gamma distribution describing spatial variability of storage capacity; and simple measures of the seasonality of mean precipitation intensity, storm arrival rate, and potential evapotranspiration. The hypothesis is tested in an application of the model to the United States east of the Rocky Mountains, with no calibration. Study area averages of runoff and evapotranspiration, based on observations, are 263 mm and 728 mm, respectively; the model yields corresponding estimates of 250 mm and 741 mm, respectively, and explains 88% of the geographical variance of observed runoff within the study region. The differences between modeled and observed runoff can be explained by uncertainties in the model inputs and in the observed runoff. In the humid (index of dryness <1) parts of the study area, the dominant factor producing runoff is the excess of annual precipitation over annual potential evapotranspiration, but runoff caused by variability of supply and demand over time is also significant; in the arid (index of dryness >1) parts, all of the runoff is caused by variability of forcing over time. Contributions to model runoff attributable to small-scale spatial variability of storage capacity are insignificant throughout the study area. The consistency of the model with observational data is supportive of the supply-demand-storage hypothesis, which neglects infiltration excess runoff and other finite-permeability effects on the soil water balance.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/94WR00586","usgsCitation":"Milly, P., 1994, Climate, soil water storage, and the average annual water balance: Water Resources Research, v. 30, no. 7, p. 2143-2156, https://doi.org/10.1029/94WR00586.","productDescription":"14 p. ","startPage":"2143","endPage":"2156","costCenters":[],"links":[{"id":340424,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"30","issue":"7","noUsgsAuthors":false,"publicationDate":"2010-07-09","publicationStatus":"PW","scienceBaseUri":"59006082e4b0e85db3a5df08","contributors":{"authors":[{"text":"Milly, P. C. D.","contributorId":100489,"corporation":false,"usgs":true,"family":"Milly","given":"P. C. D.","affiliations":[],"preferred":false,"id":692977,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70185413,"text":"70185413 - 1994 - Geochemical interactions between constituents in acidic groundwater and alluvium in an aquifer near Globe, Arizona","interactions":[],"lastModifiedDate":"2019-02-27T10:39:07","indexId":"70185413","displayToPublicDate":"1994-07-01T00:00:00","publicationYear":"1994","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":"Geochemical interactions between constituents in acidic groundwater and alluvium in an aquifer near Globe, Arizona","docAbstract":"Acidic water from a copper-mining area has contaminated an alluvial aquifer and stream near Globe, Arizona. The most contaminated groundwater has a pH of 3.3, and contains about 100 mmol/1 SO4, 50 mmol/1 Fe, 11 mmol/1 Al and 3 mmol/1 Cu. Reactions between alluvium and acidic groundwater were first evaluated in laboratory column experiments. A geochemical model was developed and used in the equilibrium speciation program, MINTEQA2, to simulate breakthrough curves for different constituents from the column. The geochemical model was then used to simulate the measured changes in concentration of aqueous constituents along a flow path in the aquifer.
The pH was predominantly controlled by reaction with carbonate minerals. Where carbonates had been dissolved, adsorption of H+ by iron oxides was used to simulate pH. Acidic groundwater contained little or no dissolved oxygen, and most aqueous Fe was present as Fe(II). In the anoxic core of the plume, Fe(II) was oxidized by MnO2 to Fe(III), which then precipitated as Fe(OH)3. Attenuation of aqueous Cu, Co, Mn, Ni and Zn was a function of pH and could be quantitatively modeled with the diffuse-layer, surface complexation model in MINTEQA2. Aluminum precipitated as amorphous Al(OH)3 at pH < 4.7 and as AlOHSO4 at pH < 4.7. Aqueous Ca and SO4were close to equilibrium with gypsum.
After the alluvium in the column had reached equilibrium with acidic groundwater, uncontaminated groundwater was eluted through the column to evaluate the effect of reactants on groundwater remediation. The concentration of Fe, Mn, Cu, Co, Ni and Zn rapidly decreased to the detection limits within a few pore volumes. All of the gypsum that had precipitated initially redissolved, resulting in elevated Ca and SO4concentrations for about 5 pore volumes. Aluminum and pH exhibited the most potential for continued adverse effects on groundwater quality. As H+ desorbed from Fe(OH)3, pH remained below 4.5 for more than 20 pore volumes, resulting in dissolution of AlOHSO4 and elevated aqueous Al.
","language":"English","publisher":"Elsevier","doi":"10.1016/0883-2927(94)90058-2","usgsCitation":"Stollenwerk, K.G., 1994, Geochemical interactions between constituents in acidic groundwater and alluvium in an aquifer near Globe, Arizona: Applied Geochemistry, v. 9, no. 4, p. 353-369, https://doi.org/10.1016/0883-2927(94)90058-2.","productDescription":"17 p. ","startPage":"353","endPage":"369","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":337988,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"9","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58d23b97e4b0236b68f8296e","contributors":{"authors":[{"text":"Stollenwerk, Kenneth G. kgstolle@usgs.gov","contributorId":578,"corporation":false,"usgs":true,"family":"Stollenwerk","given":"Kenneth","email":"kgstolle@usgs.gov","middleInitial":"G.","affiliations":[],"preferred":true,"id":685508,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70207792,"text":"70207792 - 1994 - Aquatic invertebrate production in southeastern USA wetlands during winter and spring","interactions":[],"lastModifiedDate":"2020-01-10T13:03:49","indexId":"70207792","displayToPublicDate":"1994-06-30T12:51:22","publicationYear":"1994","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3750,"text":"Wetlands","onlineIssn":"1943-6246","printIssn":"0277-5212","active":true,"publicationSubtype":{"id":10}},"title":"Aquatic invertebrate production in southeastern USA wetlands during winter and spring","docAbstract":"We measured aquatic invertebrate abundance, standing stock biomass, and community production in three types of wetlands on Noxubee National Wildlife Refuge from December 1987 through April 1988. Together, Orthocyclops modestus and Daphnia pulex were the most abundant organisms collected in all habitats during both winter and spring, but each contributed little to total standing stock biomass or production. Caecidotea communis and Pristina osborni made up ≥47% of the total standing stock biomass at each site during both winter (December–February) and spring (March–May). Crangonyx gracilis, Chironomus spp., Chaoborus punctipennis, and Eclipidrilus spp. each contributed ≥5% of the total biomass at one or more wetland habitats. Estimates of aquatic invertebrate community production ranged from 930 to 1,578 mg dry weight/m2 among wetland types during winter and from 3,306 to 5,421 mg dry weight/m2 among wetland types during spring. Caecidotea communis and Pristina osborni contributed most to community production during both seasons, but particularly in beaver ponds during spring. Other taxa made up substantial portions of the community production in one or two wetland habitats.
","language":"English","publisher":"Springer","doi":"10.1007/BF03160625","usgsCitation":"Duffy, W.G., and LaBar, D., 1994, Aquatic invertebrate production in southeastern USA wetlands during winter and spring: Wetlands, v. 14, no. 2, p. 88-97, https://doi.org/10.1007/BF03160625.","productDescription":"10 p.","startPage":"88","endPage":"97","costCenters":[{"id":455,"text":"National Wetlands Research Center","active":true,"usgs":true},{"id":17705,"text":"Wetland and Aquatic Research Center","active":true,"usgs":true}],"links":[{"id":371170,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Mississippi","otherGeospatial":"Noxubee National Wildlife Refuge","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -88.86943817138672,\n 33.23179557851464\n ],\n [\n -88.71082305908202,\n 33.23179557851464\n ],\n [\n -88.71082305908202,\n 33.319340333534996\n ],\n [\n -88.86943817138672,\n 33.319340333534996\n ],\n [\n -88.86943817138672,\n 33.23179557851464\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"14","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","contributors":{"authors":[{"text":"Duffy, Walter G. wgd7001@usgs.gov","contributorId":2491,"corporation":false,"usgs":true,"family":"Duffy","given":"Walter","email":"wgd7001@usgs.gov","middleInitial":"G.","affiliations":[],"preferred":false,"id":779336,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"LaBar, Douglas","contributorId":221647,"corporation":false,"usgs":false,"family":"LaBar","given":"Douglas","email":"","affiliations":[],"preferred":false,"id":779337,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70226692,"text":"70226692 - 1994 - Gravity survey of the Mount Toondina impact structure, South Australia","interactions":[],"lastModifiedDate":"2021-12-03T16:21:57.711763","indexId":"70226692","displayToPublicDate":"1994-06-25T10:12:28","publicationYear":"1994","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2317,"text":"Journal of Geophysical Research E: Planets","active":true,"publicationSubtype":{"id":10}},"title":"Gravity survey of the Mount Toondina impact structure, South Australia","docAbstract":"Gravity and seismic reflection data, together with geologic mapping, indicate that the Mount Toondina feature in South Australia is best interpreted as an eroded 4-km-diameter impact structure consisting of a ring structural depression surrounding a pronounced central uplift. Beds at the center of the structure within the central uplift have been raised as much as 200 m from depth and deformed by convergent flow. Seismic reflection data indicate that deformation extends to depths of only ≈800 m; at greater depths the reflectors are nearly flat lying, indicating little or no deformation. Gravity data show residual anomalies of +1.0 mGal coincident with the central uplift and a −0.5 Mgal low associated with the ring structural depression. Modeling of the gravity data indicates that relatively high-density material occurs within the central uplift, whereas the ring depression is filled with low-density material. The deformation at Mount Toondina is typical of a complex impact crater; the 4-km diameter is consistent with the expected threshold size for complex craters formed in weak to moderate strength sedimentary rocks.
The Potomac-Raritan-Magothy aquifer system in Middlesex and Monmouth Counties in the northern Coastal Plain of New Jersey consists primarily of unconsolidated Cretaceous sediments, which are divided into the upper and middle aquifers and confining units. These units, which strike northeastsouthwest along the Fall Line, dip and thicken to the southeast. The upper aquifer consists primarily of the Old Bridge Sand Member of the Magothy Formation, which is composed of coarse-grained sands, localized thin clay beds, and younger surficial sands and gravels in and near the outcrop. Transmissivity ranges from 1,760 to 19,400 ft2/d (feet squared per day) and tends to be higher in updip areas. Estimated withdrawals from the upper aquifer in the northern Coastal Plain were approximately 42 Mgal/d (million gallons per day) in 1986. Cones of depression whose centers range from 36 to 42 ft (feet) below sea level have developed as a result of these withdrawals.
\nThe upper aquifer is confined throughout most of the northern New Jersey Coastal Plain by clays and silts of the Cretaceous Woodbury Clay and Merchantville Formation and younger sediments of the Magothy Formation. This confining unit generally is greater than 200 ft thick. The simulated vertical hydraulic conductivity for the confining unit ranges from 8.4 x 10-5 to 5.6 x 10-3 feet per day; interpreted vertical hydraulic conductivities generally are lower except in southwestern Middlesex County, where the vertical hydraulic conductivities of the confining unit are higher.
\nThe middle aquifer consists primarily of the Farrington Sand Member of the Cretaceous Raritan Formation and surficial Holocene and Miocene sands and gravels in its outcrop area. It also can include the uppermost sands of the Cretaceous Potomac Group in parts of Monmouth County. The middle aquifer is composed of fine to coarse sand that contains some lignite and pyrite, and, locally, some clay beds. It pinches out in the northern part of Sayreville Township, near Raritan River. The transmissivity of the aquifer ranges from 2,140 to 13,800 ft2/d and tends to decrease in the northern part of the northern Coastal Plain of New Jersey where the aquifer thins. A poorly permeable confining unit composed mostly of clays and silts of the Woodbridge Clay Member of the Raritan Formation overlies the aquifer in most of this area. The confining unit generally is greater than 100 ft thick, although it thins and is sandy in the southwestern part of Middlesex County, where a good hydraulic connection exists between the middle and upper aquifers. Estimated withdrawals from the middle aquifer in the northern Coastal Plain were about 22 Mgal/d in 1986. These withdrawals have caused cones of depression whose centers range from 77 to 93 ft below sea level.
\nA finite-difference, quasi-three-dimensional ground-water flow model was developed to simulate ground-water flow in the aquifer system. The confined and unconfined areas of the upper and middle aquifers were modeled as separate layers. The model was calibrated primarily by adjusting vertical hydraulic conductivity in the confining units and horizontal hydraulic conductivity in the aquifers, then matching simulated and measured groundwater levels for the period 1896-1986 and simulated and interpreted potentiometric surfaces under predevelopment conditions and in 1984.
\nFor the predevelopment period, the total flow into and out of the upper and middle aquifers is 35 and 21 Mgal/d, respectively. Recharge to the aquifer system is from direct recharge in the unconfined areas and from vertical leakage through overlying confining units. The main recharge areas are the topographically high areas in southwestern Middlesex County for both aquifers, in the eastern Sayreville area for the upper aquifer, and north of the Raritan River for the middle aquifer. Most ground water discharges to low-lying regional surface-water drains (streams), which flow into the South River.
\nFor 1984 transient conditions, the total ground-water flow into and out of the upper and middle aquifers is 61 and 34 Mgal/d, respectively. The largest amount of recharge is from direct recharge in the unconfined areas, but some recharge also is derived from vertical leakage through the Merchantville-Woodbury confining unit, captured ground-water discharge to streams, and induced inflow at artificial-recharge facilities. Regional flow is from recharge areas toward major cones of depression.
\nSensitivity analysis showed that the model was useful for representing flow in the system, especially in the confined-aquifer areas. Model representation of lateral and vertical boundary conditions was judged acceptable. Simulation results were less sensitive to changes in aquifer properties in the unconfined areas of the aquifers and to changes in storage in the confining units. Sensitivity analysis and calibration of hydraulic parameters and conditions showed that the distribution of hydraulic head was sensitive to changes in horizontal hydraulic conductivity in the aquifers, vertical hydraulic conductivity in the confining units, magnitudes of ground-water withdrawals, and initial hydraulic head in aquifer outcrop areas.
\nTwo scenarios were simulated to determine the effects of ground-water withdrawals from 1986 through 2019. For the scenario in which ground-water withdrawals increase to about 69 Mgal/d in the upper aquifer and 37 Mgal/d in the middle aquifer, centers of cones of depression are as deep as 100 ft below sea level in the upper aquifer and 170 ft below sea level in the middle aquifer. For this scenario, most of the additional water comes from captured surface-water discharge, induced cross-formational flow from overlying aquifers, and increases in induced flow from artificial-recharge areas. Induced flow from Raritan Bay also increases. For the scenario in which ground water withdrawals are reduced to 42.5 Mgal/d in the upper aquifer and 15 Mgal/d in the middle aquifer, water levels recover to above sea level nearly everywhere. In each aquifer, ground-water discharge to streams increases and induced flow through the confining units and from the overlying sediments decreases, and discharge of ground water to Raritan Bay in the upper aquifer exceeds the induced recharge from Raritan Bay.
\nReversal of ground-water gradients has caused saltwater intrusion in the two aquifers. Chloride concentrations in water from the upper aquifer in Keyport and Union Beach Boroughs were as high as 2,100 mg/L (milligrams per liter) in 1986. The intrusion has not increased significantly since well fields in the area were closed in the late 1970's. Elevated chloride concentrations also were measured in Keanesburg Borough in 1986. In both of these areas, saltwater has entered the upper aquifer from the Bay because of movement of the freshwater-saltwater interface in response to increasing ground-water withdrawals.
\nChloride concentrations in well-water samples from the middle aquifer were as high as 6,000 mg/L in Sayreville Borough in 1987; concentrations in samples from drive-point wells from the same aquifer near the Washington Canal, the main source of saltwater, were as high as 7,100 mg/L. The migration of the saltwater front at about 470 feet per year to the southeast is influenced mainly by a thinning of the middle aquifer, which constrains flow, and by the locations of regional cones of depression caused by groundwater withdrawals.
","language":"English","publisher":"New Jersey Department of Environmental Protection and Energy","publisherLocation":"Trenton, NJ","collaboration":"Prepared in cooperation with the New Jersey Department of Environmental Protection and Energy Division of Science and Research Geological Survey","usgsCitation":"Pucci, A.A., Pope, D.A., and Gronberg, J.M., 1994, Hydrogeology, simulation of regional ground-water flow, and saltwater intrusion, Potomac-Raritan-Magothy Aquifer System, Northern Coastal Plain of New Jersey: New Jersey Geological Survey Report 36, Report: xi, 209 p.; 2 Plates: 34.08 x 31.75 inches and 34.42 x 31.83 inches.","productDescription":"Report: xi, 209 p.; 2 Plates: 34.08 x 31.75 inches and 34.42 x 31.83 inches","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[],"links":[{"id":310059,"rank":2,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/70159214.jpg"},{"id":311244,"rank":1,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/unnumbered/70159214/report.pdf","text":"Report","linkFileType":{"id":1,"text":"pdf"},"description":"Report"},{"id":327410,"rank":4,"type":{"id":17,"text":"Plate"},"url":"https://pubs.usgs.gov/unnumbered/70159214/plate-2.pdf"},{"id":327409,"rank":3,"type":{"id":17,"text":"Plate"},"url":"https://pubs.usgs.gov/unnumbered/70159214/plate-1.pdf"}],"country":"United States","state":"New Jersey","county":"Mercer County, Middlesex County, Monmouth County","otherGeospatial":"Potomac-Raritan-Magothy Aquifer System, Raritan Bay","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -74.6,\n 40.1\n ],\n [\n -74.6,\n 40.6\n ],\n [\n -73.97,\n 40.6\n ],\n [\n -73.97,\n 40.1\n ],\n [\n -74.6,\n 40.1\n ]\n ]\n ]\n }\n }\n ]\n}","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"56261475e4b0fb9a11dd7635","contributors":{"authors":[{"text":"Pucci, Amleto A. Jr.","contributorId":86494,"corporation":false,"usgs":true,"family":"Pucci","given":"Amleto","suffix":"Jr.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":577850,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Pope, Daryll A. dpope@usgs.gov","contributorId":3796,"corporation":false,"usgs":true,"family":"Pope","given":"Daryll","email":"dpope@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":577851,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gronberg, JoAnn M. 0000-0003-4822-7434 jmgronbe@usgs.gov","orcid":"https://orcid.org/0000-0003-4822-7434","contributorId":3548,"corporation":false,"usgs":true,"family":"Gronberg","given":"JoAnn","email":"jmgronbe@usgs.gov","middleInitial":"M.","affiliations":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"preferred":true,"id":577852,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70209150,"text":"70209150 - 1994 - Seismic guided waves trapped in the fault zone of the Landers, California, earthquake of 1992","interactions":[],"lastModifiedDate":"2020-03-20T07:35:52","indexId":"70209150","displayToPublicDate":"1994-06-10T10:50:29","publicationYear":"1994","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":"Seismic guided waves trapped in the fault zone of the Landers, California, earthquake of 1992","docAbstract":"A mobile seismic array of seven stations was deployed at 11 sites along the fault trace of the M7.4 Landers earthquake of June 28, 1992, with a maximum offset of 1 km from the trace. We found a distinct wave train with a relatively long period following the S waves that shows up only when both the stations and the events are close to the fault trace. This wave train is interpreted as a seismic guided wave trapped in a low‐velocity fault zone. To study the distribution of amplitude of the guided waves with distance from the fault trace and also their attenuation with travel distance along the fault zone, we eliminated source and recording site effects by the coda normalization method. The normalized amplitudes of guided waves show a spectral peak at 3–4 Hz, which decays sharply with distance from the fault trace. Spectral amplitudes at high frequencies (8–15 Hz) show an opposite trend, increasing with distance from the fault trace. The normalized amplitudes of guided waves at 3–4 Hz also show a systematic decrease with hypocentral distance along the fault zone, from which we infer an apparent Q of 50. In order to confirm the existence of the guided waves, a dense array of 31 stations was deployed at one of the 11 sites. The resultant records revealed unequivocal evidence for the existence of guided waves associated with the fault zone. By modeling the waveforms as S waves trapped in a low‐velocity waveguide sandwiched between two homogeneous half‐spaces with velocity Vs = 3.0 km/s, we infer a waveguide width of about 180 m, a shear velocity of 2.0–2.2 km/s, and a Q of ∼50. Hypocenters of aftershocks with clear guided waves show a systematic distribution both laterally and with depth delineating the extent of the low‐velocity fault zone in three dimensions. We find that the zone extends to a depth of at least 10 km. This zone apparently continues to the south across the Pinto Mountain fault because guided waves are observed at stations north of the Pinto Mountain fault for earthquakes with epicenters south of it. On the other hand, the zone appears to be discontinuous at the fault bend located about 20 km north of the mainshock epicenter; guided waves were observed for stations and epicenters which are located on the same sides of the fault bend but not for those on the opposite sides.
We investigated habitat specificity of the amber darter (Percina antesella Williams & Etnier 1977), an imperiled fish from restricted portions of 2 rivers in the southeastern United States. Foraging amber darters occupied a narrow range of riffle habitat, consistently avoiding areas < 20 cm deep and with velocity < 10 cm. s−1 near the substrate, occupying areas with cobble or gravel substrate and average water-column velocity of 30 to 70 cm. s−1. During low to moderate flows, approximately 20% or more of the study areas contained suitable habitat for the species. Amber darters appeared rare, and the numbers of individuals were uncorrelated with the concurrent availability of suitable habitat. Protecting the amber darter may require more than maintaining adequate depths and velocities over gravel-cobble substrates. Until we understand the potential importance of migration and dispersal for maintaining small populations, suitable habitat should be maintained over the longest contiguous stream segments possible.
","language":"English","publisher":"Wiley","doi":"10.1111/j.1600-0633.1994.tb00106.x","usgsCitation":"Freeman, B.J., and Freeman, M.C., 1994, Habitat use by an endangered riverine fish and implications for species protection: Ecology of Freshwater Fish, v. 3, no. 2, p. 49-58, https://doi.org/10.1111/j.1600-0633.1994.tb00106.x.","productDescription":"10 p.","startPage":"49","endPage":"58","numberOfPages":"10","costCenters":[{"id":531,"text":"Patuxent Wildlife Research Center","active":true,"usgs":true}],"links":[{"id":199761,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","otherGeospatial":"southeastern United States","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -94.21875,\n 24.686952411999155\n ],\n [\n -74.35546875,\n 24.686952411999155\n ],\n [\n -74.35546875,\n 36.80928470205937\n ],\n [\n -94.21875,\n 36.80928470205937\n ],\n [\n -94.21875,\n 24.686952411999155\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"3","issue":"2","noUsgsAuthors":false,"publicationDate":"2006-06-30","publicationStatus":"PW","scienceBaseUri":"4f4e4a7ee4b07f02db6485de","contributors":{"authors":[{"text":"Freeman, B. J.","contributorId":8031,"corporation":false,"usgs":true,"family":"Freeman","given":"B.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":338500,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Freeman, Mary C. 0000-0001-7615-6923","orcid":"https://orcid.org/0000-0001-7615-6923","contributorId":99659,"corporation":false,"usgs":true,"family":"Freeman","given":"Mary","email":"","middleInitial":"C.","affiliations":[{"id":531,"text":"Patuxent Wildlife Research Center","active":true,"usgs":true}],"preferred":false,"id":338501,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70248023,"text":"70248023 - 1994 - CASERTZ aeromagnetic data reveal late Cenozoic flood basalts(?) in the West Antarctic rift system","interactions":[],"lastModifiedDate":"2023-08-31T14:15:56.6117","indexId":"70248023","displayToPublicDate":"1994-06-01T09:04:46","publicationYear":"1994","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1796,"text":"Geology","active":true,"publicationSubtype":{"id":10}},"title":"CASERTZ aeromagnetic data reveal late Cenozoic flood basalts(?) in the West Antarctic rift system","docAbstract":"The late Cenozoic volcanic and tectonic activity of the enigmatic West Antarctic rift system, the least understood of the great active continental rifts, has been suggested to be plume driven. In 1991-1992, as part of the CASERTZ (Corridor Aerogeophysics of the Southeast Ross Transect Zone) program, an ∼25000 km aeromagnetic survey over the ice-covered Byrd subglacial basin shows magnetic \"texture\" critical to interpretations of the underlying extended volcanic terrane. The aeromagnetic data reveal numerous semicircular anomalies ∼100-1100 nT in amplitude, interpreted as having volcanic sources at the base of the ice sheet; they are concentrated along north-trending magnetic lineations interpreted as rift fabric. Models constrained by coincident radar ice soundings indicate highly magnetic sources, with a probable high remanent magnetization in the present field direction, strongly suggesting a late Cenozoic age. Magnetic anomalies over exposed late Cenozoic volcanic rocks along part of the rift shoulder and in coastal Marie Byrd Land are similar in form and amplitude. The CASERTZ aeromagnetic results, combined with >100 000 km of widely spaced aeromagnetic profiles, indicate at least 106 km3 of probable late Cenozoic volcanic rock (flood basalt?) in the West Antarctic rift beneath the ice sheet and Ross Ice Shelf. Comparison with other plumes in active rift areas (e.g., Yellowstone and East Africa) indicates that this volume estimate lies in the range of magma generation found in these other low-extension continental rifts.
","language":"English","publisher":"Geological Society of America","doi":"10.1130/0091-7613(1994)022<0527:CADRLC>2.3.CO;2","usgsCitation":"Behrendt, J.C., Blankenship, D.D., Finn, C.A., Bell, R.E., Sweeney, R.E., Hodge, S.M., and Brozena, J.M., 1994, CASERTZ aeromagnetic data reveal late Cenozoic flood basalts(?) in the West Antarctic rift system: Geology, v. 22, no. 6, p. 527-530, https://doi.org/10.1130/0091-7613(1994)022<0527:CADRLC>2.3.CO;2.","productDescription":"4 p.","startPage":"527","endPage":"530","costCenters":[],"links":[{"id":420364,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"otherGeospatial":"Antarctica, West Antarctic Rift System","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -194.8213500504204,\n -67.70510605720003\n ],\n [\n -194.8213500504204,\n -78.68678902524067\n ],\n [\n -149.03710299605495,\n -78.68678902524067\n ],\n [\n -149.03710299605495,\n -67.70510605720003\n ],\n [\n -194.8213500504204,\n -67.70510605720003\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"22","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","contributors":{"authors":[{"text":"Behrendt, John C. jbehrendt@usgs.gov","contributorId":25945,"corporation":false,"usgs":true,"family":"Behrendt","given":"John","email":"jbehrendt@usgs.gov","middleInitial":"C.","affiliations":[{"id":218,"text":"Denver Federal Center","active":false,"usgs":true},{"id":213,"text":"Crustal Imaging and Characterization Team","active":false,"usgs":true}],"preferred":false,"id":881535,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Blankenship, D. D.","contributorId":29012,"corporation":false,"usgs":false,"family":"Blankenship","given":"D.","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":881536,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Finn, Carol A. 0000-0002-6178-0405 cfinn@usgs.gov","orcid":"https://orcid.org/0000-0002-6178-0405","contributorId":1326,"corporation":false,"usgs":true,"family":"Finn","given":"Carol","email":"cfinn@usgs.gov","middleInitial":"A.","affiliations":[{"id":211,"text":"Crustal Geophysics and Geochemistry Science Center","active":true,"usgs":true}],"preferred":true,"id":881537,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Bell, Robin E.","contributorId":26902,"corporation":false,"usgs":true,"family":"Bell","given":"Robin","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":881538,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sweeney, Ronald E.","contributorId":89564,"corporation":false,"usgs":true,"family":"Sweeney","given":"Ronald","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":881539,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Hodge, Steven M.","contributorId":68467,"corporation":false,"usgs":true,"family":"Hodge","given":"Steven","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":881540,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Brozena, John M.","contributorId":58755,"corporation":false,"usgs":true,"family":"Brozena","given":"John","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":881541,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70243630,"text":"70243630 - 1994 - Petrogenesis of the highly potassic 1.42 Ga Barrel Spring pluton, southeastern California, with implications for mid-Proterozoic magma genesis in the southwestern USA","interactions":[],"lastModifiedDate":"2023-05-16T11:49:04.350551","indexId":"70243630","displayToPublicDate":"1994-06-01T06:27:07","publicationYear":"1994","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1336,"text":"Contributions to Mineralogy and Petrology","active":true,"publicationSubtype":{"id":10}},"title":"Petrogenesis of the highly potassic 1.42 Ga Barrel Spring pluton, southeastern California, with implications for mid-Proterozoic magma genesis in the southwestern USA","docAbstract":"Syenites from the Barrel Spring pluton were emplaced in the Early Proterozoic Mojave crustal provine of southeastern California at 1.42 Ga. All rocks, even the most mafic, are highly enriched in incompatible elements (e.g. K2O 4–12 wt%, Rb 170–370 ppm, Th 12–120 ppm, La 350–1500xchondrite, La/Ybn 35–100). Elemental compositions require an incompatible element-rich but mafic (or ultramafic) source. Trace element models establish two plausible sources for Barrel Spring magmas: (1) LREE enriched garnet websterite with accessory apatite±rutile (enriched lithospheric mantle), and (2) garnet amphibolite or garnet-hornblende granulite with enriched alkali basalt composition, also with accessory apatite±rutile (mafic lower crust). Nd and Pb isotopic ratios do not distinguish a crust vs mantle source, but eliminate local Mojave province crust as the principal one, and indicate that generation of the enriched source occurred several hundred million years before emplacement of the Barrel Spring pluton. 1.40–1.44 Ga potassic granites are common in southeastern California, suggesting a genetic link between the Barrel Spring pluton and the granites; however, although the same thermal regime was probably responsible for producing both the granitic and syentic magmas, elemental and isotopic compositions preclude a close relationship. Isotopic similarity of the Barrel Spring pluton to 1.40–1.44 Ga granites emplaced in the Central Arizona crustal province to the east may imply that a common component was present in the lithosphere of these generally distinct regions.
This article presents evidence for the channeling of strain energy released by the Ms = 7.4 Landers, California, earthquake within the eastern California shear zone (ECSZ). We document an increase in seismicity levels during the 22-hr period starting with the Landers earthquake and culminating 22 hr later with the Ms = 5.4 Little Skull Mountain (LSM), Nevada, earthquake. We evaluate the completeness of regional seismicity catalogs during this period and find that the continuity of post-Landers strain release within the ECSZ is even more pronounced than is evident from the catalog data. We hypothesize that regional-scale connectivity of faults within the ECSZ and LSM region is a critical ingredient in the unprecedented scale and distribution of remotely triggered earthquakes and geodetically manifest strain changes that followed the Landers earthquake. The viability of static strain changes as triggering agents is tested using numerical models. Modeling results illustrate that regional-scale fault connectivity can increase the static strain changes by approximately an order of magnitude at distances of at least 280 km, the distance between the Landers and LSM epicenters. This is possible for models that include both a network of connected faults that slip “sympathetically” and realistic levels of tectonic prestrain. Alternatively, if dynamic strains are a more significant triggering agent than static strains, ECSZ structure may still be important in determining the distribution of triggered seismic and aseismic deformation.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840030835","usgsCitation":"Bodin, P., and Gomberg, J., 1994, Triggered seismicity and deformation between the Landers, California, and Little Skull Mountain, Nevada, earthquakes: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 835-843, https://doi.org/10.1785/BSSA0840030835.","productDescription":"9 p.","startPage":"835","endPage":"843","costCenters":[],"links":[{"id":339033,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":339032,"rank":2,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.geoscienceworld.org/ssa/bssa/article/84/3/835/102710/Triggered-seismicity-and-deformation-between-the"}],"country":"United States","state":"California, Nevada","otherGeospatial":"Landers, Little Skull Mountain","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -117.48148758019548,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 35.175884043309324\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n },\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -116.25731325331711,\n 36.84237299356687\n ],\n [\n -116.25731325331711,\n 36.70827842185419\n ],\n [\n -116.07294893446968,\n 36.70827842185419\n ],\n [\n -116.07294893446968,\n 36.84237299356687\n ],\n [\n -116.25731325331711,\n 36.84237299356687\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"84","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58e35f90e4b09da67997ecee","contributors":{"authors":[{"text":"Bodin, Paul","contributorId":104142,"corporation":false,"usgs":true,"family":"Bodin","given":"Paul","affiliations":[],"preferred":false,"id":688046,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gomberg, Joan","contributorId":77919,"corporation":false,"usgs":true,"family":"Gomberg","given":"Joan","affiliations":[],"preferred":false,"id":688047,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70186739,"text":"70186739 - 1994 - Foreshocks, aftershocks, and earthquake probabilities: Accounting for the landers earthquake","interactions":[],"lastModifiedDate":"2023-10-24T01:11:57.973515","indexId":"70186739","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"Foreshocks, aftershocks, and earthquake probabilities: Accounting for the landers earthquake","docAbstract":"The equation to determine the probability that an earthquake occurring near a major fault will be a foreshock to a mainshock on that fault is modified to include the case of aftershocks to a previous earthquake occurring near the fault. The addition of aftershocks to the background seismicity makes its less probable that an earthquake will be a foreshock, because nonforeshocks have become more common. As the aftershocks decay with time, the probability that an earthquake will be a foreshock increases. However, fault interactions between the first mainshock and the major fault can increase the long-term probability of a characteristic earthquake on that fault, which will, in turn, increase the probability that an event is a foreshock, compensating for the decrease caused by the aftershocks.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840030892","usgsCitation":"Jones, L.M., 1994, Foreshocks, aftershocks, and earthquake probabilities: Accounting for the landers earthquake: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 892-899, https://doi.org/10.1785/BSSA0840030892.","productDescription":"8 p.","startPage":"892","endPage":"899","costCenters":[],"links":[{"id":479331,"rank":2,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://resolver.caltech.edu/CaltechAUTHORS:20140806-111429292","text":"External Repository"},{"id":339477,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"84","issue":"3","noUsgsAuthors":false,"publicationDate":"1994-06-01","publicationStatus":"PW","scienceBaseUri":"58e8a548e4b09da6799d63cd","contributors":{"authors":[{"text":"Jones, Lucile M. jones@usgs.gov","contributorId":1014,"corporation":false,"usgs":true,"family":"Jones","given":"Lucile","email":"jones@usgs.gov","middleInitial":"M.","affiliations":[{"id":508,"text":"Office of the AD Hazards","active":true,"usgs":true}],"preferred":true,"id":690420,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70186588,"text":"70186588 - 1994 - Dense array recordings in the San Bernardino Valley of landers-big bear aftershocks: Basin surface waves, Moho reflections, and three-dimensional simulations","interactions":[],"lastModifiedDate":"2017-04-05T15:40:45","indexId":"70186588","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"Dense array recordings in the San Bernardino Valley of landers-big bear aftershocks: Basin surface waves, Moho reflections, and three-dimensional simulations","docAbstract":"Fourteen GEOS seismic recorders were deployed in the San Bernardino Valley to study the propagation of short-period (T ≈ 1 to 3 sec) surface waves and Moho reflections. Three dense arrays were used to determine the direction and speed of propagation of arrivals in the seismograms. The seismograms for a shallow (d ≈ 1 km) M 4.9 aftershock of the Big Bear earthquake exhibit a very long duration (60 sec) of sustained shaking at periods of about 2 sec. Array analysis indicates that these late arrivals are dominated by surface waves traveling in various directions across the Valley. Some energy is arriving from a direction 180° from the epicenter and was apparently reflected from the edge of the Valley opposite the source. A close-in aftershock (Δ = 25 km, depth = 7 km) displays substantial short-period surface waves at deep-soil sites. A three-dimensional (3D) finite difference simulation produces synthetic seismograms with durations similar to those of the observed records for this event, indicating the importance of S-wave to surface-wave conversion near the edge of the basin. Flat-layered models severely underpredict the duration and spectral amplification of this deep-soil site. I show an example where the coda wave amplitude ratio at 1 to 2 Hz between a deep-soil and a rock site does not equal the S-wave amplitude ratio, because of the presence of surface waves in the coda of the deep-soil site. For one of the events studied (Δ ≈ 90 km), there are sizable phases that are critically reflected from the Moho (PmP and SmS). At one of the rock sites, the SmS phase has a more peaked spectrum that the direct S wave.
","language":"English","publisher":"Seismological Society of America","usgsCitation":"Frankel, A., 1994, Dense array recordings in the San Bernardino Valley of landers-big bear aftershocks: Basin surface waves, Moho reflections, and three-dimensional simulations: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 613-624.","productDescription":"12 p. ","startPage":"613","endPage":"624","costCenters":[],"links":[{"id":339259,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":339258,"rank":1,"type":{"id":15,"text":"Index Page"},"url":"https://www.bssaonline.org/content/84/3/613.abstract"}],"volume":"84","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58e60277e4b09da6799ac6a7","contributors":{"authors":[{"text":"Frankel, Arthur","contributorId":103761,"corporation":false,"usgs":true,"family":"Frankel","given":"Arthur","affiliations":[],"preferred":false,"id":689661,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70186624,"text":"70186624 - 1994 - Triggering of the Ms = 5.4 Little Skull Mountain, Nevada, earthquake with dynamic strains","interactions":[],"lastModifiedDate":"2023-10-25T11:09:27.553463","indexId":"70186624","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"Triggering of the Ms = 5.4 Little Skull Mountain, Nevada, earthquake with dynamic strains","docAbstract":"We have developed an approach to test the viability of dynamic strains as a triggering mechanism by quantifying the dynamic strain tensor at seismogenic depths. We focus on the dynamic strains at the hypocenter of the Ms = 5.4 Little Skull Mountain (LSM), Nevada, earthquake. This event is noteworthy because it is the largest earthquake demonstrably triggered at remote distances (∼280 km) by the Ms = 7.4 Landers, California, earthquake and because of its ambiguous association with magmatic activity. Our analysis shows that, if dynamic strains initiate remote triggering, the orientation and modes of faulting most favorable for being triggered by a given strain transient change with depth. The geometry of the most probable LSM fault plane was favorably oriented with respect to the geometry of the dynamic strain tensor. We estimate that the magnitude of the peak dynamic strains at the hypocentral depth of the LSM earthquake were ∼4 μstrain (∼.2 MPa) which are ∼50% smaller than those estimated from velocity seismograms recorded at the surface. We suggest that these strains are too small to cause Mohr-Coulomb style failure unless the fault was prestrained to near failure levels, the fault was exceptionally weak, and/or the dynamic strains trigger other processes that lead to failure.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840030844","usgsCitation":"Gomberg, J., and Bodin, P., 1994, Triggering of the Ms = 5.4 Little Skull Mountain, Nevada, earthquake with dynamic strains: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 844-853, https://doi.org/10.1785/BSSA0840030844.","productDescription":"10 p.","startPage":"844","endPage":"853","costCenters":[],"links":[{"id":339311,"rank":2,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.geoscienceworld.org/ssa/bssa/article/84/3/844/102716/Triggering-of-the-Ms-5-4-Little-Skull-Mountain"},{"id":339312,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Nevada","otherGeospatial":"Little Skull Mountain","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -116.26116425515113,\n 36.83416633494588\n ],\n [\n -116.26116425515113,\n 36.7071096190553\n ],\n [\n -116.07920319558086,\n 36.7071096190553\n ],\n [\n -116.07920319558086,\n 36.83416633494588\n ],\n [\n -116.26116425515113,\n 36.83416633494588\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"84","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58e75405e4b09da6799c0c7e","contributors":{"authors":[{"text":"Gomberg, Joan","contributorId":77919,"corporation":false,"usgs":true,"family":"Gomberg","given":"Joan","affiliations":[],"preferred":false,"id":690075,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Bodin, Paul","contributorId":104142,"corporation":false,"usgs":true,"family":"Bodin","given":"Paul","affiliations":[],"preferred":false,"id":690076,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70186590,"text":"70186590 - 1994 - The co-seismic slip distribution of the Landers earthquake","interactions":[],"lastModifiedDate":"2023-10-24T11:05:10.69335","indexId":"70186590","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"The co-seismic slip distribution of the Landers earthquake","docAbstract":"We derived a model for the co-seismic slip distribution on the faults which ruptured during the Landers earthquake sequence of 28 June 1992. The model is based on the inversion of surface geodetic measurements, primarily vector displacements measured using the Global Positioning System (GPS). The inversion procedure assumes that the slip distribution is to some extent smooth and purely right-lateral strike slip. For a given fault geometry, a family of solutions of varying smoothness can be generated.
We choose the optimal model from this family based on cross-validation, which measures the predictive power of the data, and the trade-off of misfit and roughness. Solutions which give roughly equal weight to misfit and smoothness are preferred and have certain features in common: (1) there are two main patches of slip, on the Johnson Valley fault, and on the Homestead Valley, Emerson, and Camp Rock faults; (2) virtually all slip is in the upper 10 to 12 km; and (3) the model reproduces the general features of the geologically measured surface displacements, without prior constraints on the surface slip. In all models, regardless of smoothing, very little slip is required on the fault that represents the Big Bear event, and the total moment of the Landers event is 9 · 1019 N-m. The nearly simultaneous rupture of multiple distinct faults suggests that much of the crust in this region must have been close to failure prior to the earthquake.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840030646","usgsCitation":"Freymueller, J., King, N., and Segall, P., 1994, The co-seismic slip distribution of the Landers earthquake: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 646-659, https://doi.org/10.1785/BSSA0840030646.","productDescription":"14 p.","startPage":"646","endPage":"659","costCenters":[],"links":[{"id":339264,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -117.48148758019548,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 35.175884043309324\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"84","issue":"3","noUsgsAuthors":false,"publicationDate":"1994-06-01","publicationStatus":"PW","scienceBaseUri":"58e60277e4b09da6799ac6a5","contributors":{"authors":[{"text":"Freymueller, J.","contributorId":190583,"corporation":false,"usgs":false,"family":"Freymueller","given":"J.","affiliations":[],"preferred":false,"id":689665,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"King, N.E.","contributorId":29950,"corporation":false,"usgs":true,"family":"King","given":"N.E.","email":"","affiliations":[],"preferred":false,"id":689666,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Segall, P.","contributorId":44231,"corporation":false,"usgs":false,"family":"Segall","given":"P.","affiliations":[],"preferred":false,"id":689667,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70186737,"text":"70186737 - 1994 - Continuous borehole strain in the San Andreas fault zone before, during, and after the 28 June 1992, MW 7.3 Landers, California, earthquake","interactions":[],"lastModifiedDate":"2023-10-25T11:03:49.236269","indexId":"70186737","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"Continuous borehole strain in the San Andreas fault zone before, during, and after the 28 June 1992, MW 7.3 Landers, California, earthquake","docAbstract":"High-precision strain was observed with a borehole dilational strainmeter in the Devil's Punchbowl during the 11:58 UT 28 June 1992 MW 7.3 Landers earthquake and the large Big Bear aftershock (MW 6.3). The strainmeter is installed at a depth of 176 m in the fault zone approximately midway between the surface traces of the San Andreas and Punchbowl faults and is about 100 km from the 85-km-long Landers rupture. We have questioned whether unusual amplified strains indicating precursive slip or high fault compliance occurred on the faults ruptured by the Landers earthquake, or in the San Andreas fault zone before and during the earthquake, whether static offsets for both the Landers and Big Bear earthquakes agree with expectation from geodetic and seismologic models of the ruptures and with observations from a nearby two-color geodimeter network, and whether postseismic behavior indicated continued slip on the Landers rupture or local triggered slip on the San Andreas. We show that the strain observed during the earthquake at this instrument shows no apparent amplification effects. There are no indications of precursive strain in these strain data due to either local slip on the San Andreas or precursive slip on the eventual Landers rupture. The observations are generally consistent with models of the earthquake in which fault geometry and slip have the same form as that determined by either inversion of the seismic data or inversion of geodetically determined ground displacements produced by the earthquake. Finally, there are some indications of minor postseismic behavior, particularly during the month following the earthquake.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840030799","usgsCitation":"Johnston, M., Linde, A.T., and Agnew, D., 1994, Continuous borehole strain in the San Andreas fault zone before, during, and after the 28 June 1992, MW 7.3 Landers, California, earthquake: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 799-805, https://doi.org/10.1785/BSSA0840030799.","productDescription":"7 p.","startPage":"799","endPage":"805","costCenters":[],"links":[{"id":339472,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -117.48148758019548,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 35.175884043309324\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"84","issue":"3","noUsgsAuthors":false,"publicationDate":"1994-06-01","publicationStatus":"PW","scienceBaseUri":"58e8a549e4b09da6799d63d1","contributors":{"authors":[{"text":"Johnston, M.J.S. 0000-0003-4326-8368","orcid":"https://orcid.org/0000-0003-4326-8368","contributorId":104889,"corporation":false,"usgs":true,"family":"Johnston","given":"M.J.S.","affiliations":[],"preferred":false,"id":690414,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Linde, A. T.","contributorId":21700,"corporation":false,"usgs":true,"family":"Linde","given":"A.","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":690415,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Agnew, D.C.","contributorId":32186,"corporation":false,"usgs":true,"family":"Agnew","given":"D.C.","email":"","affiliations":[],"preferred":false,"id":690416,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70186738,"text":"70186738 - 1994 - Magnetic field observations in the near-field the 28 June 1992 Mw 7.3 Landers, California, earthquake","interactions":[],"lastModifiedDate":"2023-10-24T01:15:51.116012","indexId":"70186738","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"Magnetic field observations in the near-field the 28 June 1992 Mw 7.3 Landers, California, earthquake","docAbstract":"Recent reports suggest that large magnetic field changes occur prior to, and during, large earthquakes. Two continuously operating proton magnetometers, LSBM and OCHM, at distances of 17.3 and 24.2 km, respectively, from the epicenter of the 28 June 1992 Mw 7.3 Landers earthquake, recorded data through the earthquake and its aftershocks. These two stations are part of a differentially connected array of proton magnetometers that has been operated along the San Andreas fault since 1976. The instruments have a sensitivity of 0.25 nT or better and transmit data every 10 min through the GOES satellite to the USGS headquarters in Menlo Park, California. Seismomagnetic offsets of −1.2 ± 0.6 and −0.7 ± 0.7 nT were observed at these sites. In comparison, offsets of −0.3 ± 0.2 and −1.3 ± 0.2 nT were observed during the 8 July 1986 ML 5.9 North Palm Springs earthquake, which occurred directly beneath the OCHM magnetometer site. The observations are generally consistent with seismomagnetic models of the earthquake, in which fault geometry and slip have the same from as that determined by either inversion of the seismic data or inversion of geodetically determined ground displacements produced by the earthquake. In these models, right-lateral rupture occurs on connected fault segments in a homogeneous medium with average magnetization of 2 A/m. The fault-slip distribution has roughly the same form as the observed surface rupture, and the total moment release is 1.1 × 1020 Nm. There is no indication of diffusion-like character to the magnetic field offsets that might indicate these effects result from fluid flow phenomena. It thus seems unlikely that these earthquake-generated offsets and those produced by the North Palm Springs earthquake were generated by electrokinetic effects. Also, there are no indications of enhanced low-frequency magnetic noise before the earthquake at frequencies below 0.001 Hz.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840030792","usgsCitation":"Johnston, M.J., Mueller, R., and Sasai, Y., 1994, Magnetic field observations in the near-field the 28 June 1992 Mw 7.3 Landers, California, earthquake: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 792-798, https://doi.org/10.1785/BSSA0840030792.","productDescription":"7 p.","startPage":"792","endPage":"798","costCenters":[],"links":[{"id":339474,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -117.48148758019548,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 33.55266747577443\n ],\n [\n -115.32816726769562,\n 35.175884043309324\n ],\n [\n -117.48148758019548,\n 35.175884043309324\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"84","issue":"3","noUsgsAuthors":false,"publicationDate":"1994-06-01","publicationStatus":"PW","scienceBaseUri":"58e8a549e4b09da6799d63cf","contributors":{"authors":[{"text":"Johnston, M. J.","contributorId":64255,"corporation":false,"usgs":true,"family":"Johnston","given":"M.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":690417,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Mueller, R.J.","contributorId":77135,"corporation":false,"usgs":true,"family":"Mueller","given":"R.J.","email":"","affiliations":[],"preferred":false,"id":690418,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Sasai, Yoichi","contributorId":190700,"corporation":false,"usgs":false,"family":"Sasai","given":"Yoichi","email":"","affiliations":[],"preferred":false,"id":690419,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70186690,"text":"70186690 - 1994 - Fault-zone waves observed at the southern Joshua Tree earthquake rupture zone","interactions":[],"lastModifiedDate":"2017-04-07T10:37:25","indexId":"70186690","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"Fault-zone waves observed at the southern Joshua Tree earthquake rupture zone","docAbstract":"Waveform and spectral characteristics of several aftershocks of the M 6.1 22 April 1992 Joshua Tree earthquake recorded at stations just north of the Indio Hills in the Coachella Valley can be interpreted in terms of waves propagating within narrow, low-velocity, high-attenuation, vertical zones. Evidence for our interpretation consists of: (1) emergent P arrivals prior to and opposite in polarity to the impulsive direct phase; these arrivals can be modeled as headwaves indicative of a transfault velocity contrast; (2) spectral peaks in the S wave train that can be interpreted as internally reflected, low-velocity fault-zone wave energy; and (3) spatial selectivity of event-station pairs at which these data are observed, suggesting a long, narrow geologic structure. The observed waveforms are modeled using the analytical solution of Ben-Zion and Aki (1990) for a plane-parallel layered fault-zone structure. Synthetic waveform fits to the observed data indicate the presence of NS-trending vertical fault-zone layers characterized by a thickness of 50 to 100 m, a velocity decrease of 10 to 15% relative to the surrounding rock, and a P-wave quality factor in the range 25 to 50.
","language":"English","publisher":"Seismological Society of America","usgsCitation":"Hough, S., Ben-Zion, Y., and Leary, P., 1994, Fault-zone waves observed at the southern Joshua Tree earthquake rupture zone: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 761-767.","productDescription":"7 p. ","startPage":"761","endPage":"767","costCenters":[],"links":[{"id":339404,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"84","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58e8a549e4b09da6799d63d7","contributors":{"authors":[{"text":"Hough, S. E. 0000-0002-5980-2986","orcid":"https://orcid.org/0000-0002-5980-2986","contributorId":7316,"corporation":false,"usgs":true,"family":"Hough","given":"S. E.","affiliations":[],"preferred":false,"id":690290,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ben-Zion, Y.","contributorId":190673,"corporation":false,"usgs":false,"family":"Ben-Zion","given":"Y.","affiliations":[],"preferred":false,"id":690291,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Leary, P.","contributorId":190672,"corporation":false,"usgs":false,"family":"Leary","given":"P.","email":"","affiliations":[],"preferred":false,"id":690292,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70186195,"text":"70186195 - 1994 - Local observations of the onset of a large earthquake: 28 June 1992 Landers, California","interactions":[],"lastModifiedDate":"2023-10-25T11:19:02.509054","indexId":"70186195","displayToPublicDate":"1994-06-01T00:00:00","publicationYear":"1994","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":"Local observations of the onset of a large earthquake: 28 June 1992 Landers, California","docAbstract":"The Landers earthquake (MW 7.3) of 28 June 1992 had a very emergent onset. The first large amplitude arrivals are delayed by about 3 sec with respect to the origin time, and are preceded by smaller-scale slip. Other large earthquakes have been observed to have similar emergent onsets, but the Landers event is one of the first to be well recorded on nearby stations. We used these recordings to investigate the spatial relationship between the hypocenter and the onset of the large energy release, and to determine the slip function of the 3-sec nucleation process. Relative location of the onset of the large energy release with respect to the initial hypocenter indicates its source was between 1 and 4 km north of the hypocenter and delayed by approximately 2.5 sec. Three-station array analysis of the P wave shows that the large amplitude onset arrives with a faster apparent velocity compared to the first arrivals, indicating that the large amplitude source was several kilometers deeper than the initial onset. An ML 2.8 foreshock, located close to the hypocenter, was used as an empirical Green's function to correct for path and site effects from the first 3 sec of the mainshock seismogram. The resultant deconvolution produced a slip function that showed two subevents preceding the main energy release, an MW4.4 followed by an MW 5.6. These subevents do not appear anomalous in comparison to simple moderate-sized earthquakes, suggesting that they were normal events which just triggered or grew into a much larger earthquake. If small and moderate-sized earthquakes commonly “detonate” much larger events, this implies that the dynamic stresses during earthquake rupture are at least as important as long-term static stresses in causing earthquakes, and the prospects of reliable earthquake prediction from premonitory phenomena are not improved.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0840030725","usgsCitation":"Abercrombie, R., and Mori, J., 1994, Local observations of the onset of a large earthquake: 28 June 1992 Landers, California: Bulletin of the Seismological Society of America, v. 84, no. 3, p. 725-734, https://doi.org/10.1785/BSSA0840030725.","productDescription":"10 p.","startPage":"725","endPage":"734","costCenters":[],"links":[{"id":338951,"rank":2,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.geoscienceworld.org/ssa/bssa/article/84/3/725/102652/Local-observations-of-the-onset-of-a-large"},{"id":338952,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","city":"Landers","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -116.4997100830078,\n 34.175453097578526\n ],\n [\n -116.26487731933592,\n 34.175453097578526\n ],\n [\n -116.26487731933592,\n 34.326993104644515\n ],\n [\n -116.4997100830078,\n 34.326993104644515\n ],\n [\n -116.4997100830078,\n 34.175453097578526\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"84","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58df6ac9e4b02ff32c6aea83","contributors":{"authors":[{"text":"Abercrombie, Richael","contributorId":190227,"corporation":false,"usgs":false,"family":"Abercrombie","given":"Richael","email":"","affiliations":[],"preferred":false,"id":687847,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Mori, Jim","contributorId":55840,"corporation":false,"usgs":true,"family":"Mori","given":"Jim","affiliations":[],"preferred":false,"id":687848,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ]}