Publications
Filter Total Items: 7519
An updated numerical simulation of the ground-water flow system for the Castle Lake debris dam, Mount St. Helens, Washington, and implications for dam stability against heave An updated numerical simulation of the ground-water flow system for the Castle Lake debris dam, Mount St. Helens, Washington, and implications for dam stability against heave
A numerical simulation of the ground-water flow system in the Castle Lake debris dam, calibrated to data from the 1991 and 1992 water years, was used to estimate factors of safety against heave and internal erosion. The Castle Lake debris dam, 5 miles northwest of the summit of Mount St. Helens, impounds 19,000 acre-ft of water that could pose a flood hazard in the event of a lake...
Authors
Evelyn A. Roeloffs
Probability of one or more M ≥7 earthquakes in southern California in 30 years Probability of one or more M ≥7 earthquakes in southern California in 30 years
Eight earthquakes of magnitude greater than or equal to seven have occurred in southern California in the past 200 years. If one assumes that such events are the product of a Poisson process, the probability of one or more earthquakes of magnitude seven or larger in southern California within any 30 year interval is 67% ± 23% (95% confidence interval). Because five of the eight M ≥ 7...
Authors
James C. Savage
Chapter A. The Loma Prieta, California, Earthquake of October 17, 1989 - Loss estimation and procedures Chapter A. The Loma Prieta, California, Earthquake of October 17, 1989 - Loss estimation and procedures
This Professional Paper includes a collection of papers on subjects ranging from evaluation of building safety, to human injuries, to correlation of ground deformation with building damage. What these papers share is a common goal to improve the tools available to the research community to measure the nature, extent, and causes of damage and losses due to earthquakes. These measurement...
Convective heat discharge of Wood River group of springs in the vicinity of Crater Lake, Oregon Convective heat discharge of Wood River group of springs in the vicinity of Crater Lake, Oregon
Data sets for spring and stream chemistry are combined to estimate convective heat discharge and discharge anomalous amounts of sodium and chloride for the Wood River group of springs south of Crater Lake. The best estimate of heat discharge is 87 MWt based on chloride inventory; this value is 3-5 times the heat input to Crater Lake itself. Anomalous discharges of sodium and chloride are...
Authors
Manuel Nathenson, Robert H. Mariner, J. Michael Thompson
Uranium-Series Ages of Travertines and Timing of the Last Glaciation in the Northern Yellowstone Area, Wyoming-Montana Uranium-Series Ages of Travertines and Timing of the Last Glaciation in the Northern Yellowstone Area, Wyoming-Montana
Uranium-series age determinations by mass spectrometric methods were done for travertines and associated carbonate veins related to clastic deposits of the last glaciation (Pinedale) in the northern Yellowstone area. Dramatic variations in the hydrologic head are inferred from variations in the elevation of travertine deposition with time and are consistent with the expected hydrologic...
Authors
N.C. Sturchio, K. L. Pierce, M.T. Murrell, M.L. Sorey
Potassium-argon geochronology of a basalt-andesite-dacite arc system: the Mount Adams volcanic field, Cascade Range of southern Washington Potassium-argon geochronology of a basalt-andesite-dacite arc system: the Mount Adams volcanic field, Cascade Range of southern Washington
High-precision K-Ar dating and detailed mapping have established an eruptive chronology for a Cascade stratovolcano and its surrounding array of coeval basaltic centers. The time-volume-composition data bear upon several fundamental questions concerning the long-term behavior of arc volcanoes. -from Authors
Authors
W. Hildreth, M. A. Lanphere
Magmatic vapor source for sulfur dioxide released during volcanic eruptions: Evidence from Mount Pinatubo Magmatic vapor source for sulfur dioxide released during volcanic eruptions: Evidence from Mount Pinatubo
Sulfur dioxide (SO2) released by the explosive eruption of Mount Pinatubo on 15 June 1991 had an impact on climate and stratospheric ozone. The total mass of SO2 released was much greater than the amount dissolved in the magma before the eruption, and thus an additional source for the excess SO2 is required. Infrared spectroscopic analyses of dissolved water and carbon dioxide in glass...
Authors
P.J. Wallace, T.M. Gerlach
Volcanic mixed avalanches: A distinct eruption-triggered mass-flow process at snow-clad volcanoes Volcanic mixed avalanches: A distinct eruption-triggered mass-flow process at snow-clad volcanoes
A generally unrecognized type of pyroclastic deposit was produced by rapid avalanches of intimately mixed snow and hot pyroclastic debris during eruptions at Mount St. Helens, Nevado del Ruiz, and Redoubt Volcano between 1982 and 1989. These "mixed avalanches" traveled as far as 14 km at velocities up to ∼27 m/s, involved as much as 107 m3 of rock and ice, and left unmelted deposits of...
Authors
T.C. Pierson, R. J. Janda
The East African rift system in the light of KRISP 90 The East African rift system in the light of KRISP 90
On the basis of a test experiment in 1985 (KRISP 85) an integrated seismic-refraction/teleseismic survey (KRISP 90) was undertaken to study the deep structure beneath the Kenya rift down to depths of 100–150 km. This paper summarizes the highlights of KRISP 90 as reported in this volume and discusses their broad implications as well as the structure of the Kenya rift in the general...
Authors
Gordon R. Keller, C. Prodehl, J. Mechie, K. Fuchs, M.A. Khan, Peter K.H. Maguire, Walter D. Mooney, U. Achauer, P.M. Davis, R.P. Meyer, L.W. Braile, I.O. Nyambok, G. A. Thompson
Precursory swarms of long-period events at Redoubt Volcano (1989-1990), Alaska: Their origin and use as a forecasting tool Precursory swarms of long-period events at Redoubt Volcano (1989-1990), Alaska: Their origin and use as a forecasting tool
During the eruption of Redoubt Volcano from December 1989 through April 1990, the Alaska Volcano Observatory issued advance warnings of several tephra eruptions based on changes in seismic activity related to the occurrence of precursory swarms of long-period (LP) seismic events (dominant period of about 0.5 s). The initial eruption on December 14 occurred after 23 years of quiescence...
Authors
B. A. Chouet, R.A. Page, C.D. Stephens, J.C. Lahr, J.A. Power
Fluid expulsion sites on the Cascadia accretionary prism: mapping diagenetic deposits with processed GLORIA imagery Fluid expulsion sites on the Cascadia accretionary prism: mapping diagenetic deposits with processed GLORIA imagery
Point-discharge fluid expulsion on accretionary prisms is commonly indicated by diagenetic deposition of calcium carbonate cements and gas hydrates in near-surface (
Authors
Bobb Carson, Erol Seke, Valerie F. Paskevich, Mark L. Holmes
The Geology of Gaspra The Geology of Gaspra
The surface of Gaspra can be divided into several facets separated by ridges. Superimposed on the facets and ridges are two populations of craters. Type 1 craters are crisply defined and constitute a production function of impact origin. Type 2 craters are mostly irregular shallow depressions and probably of various origins. Some of the type 2 craters may have formed by impact and be...
Authors
M. H. Carr, Randolph L. Kirk, A. McEwen, J. Veverka, P. Thomas, J.W. Head, S. Murchie