Publications
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Source mechanism of Vulcanian degassing at Popocatépetl Volcano, Mexico, determined from waveform inversions of very long period signals Source mechanism of Vulcanian degassing at Popocatépetl Volcano, Mexico, determined from waveform inversions of very long period signals
The source mechanism of very long period (VLP) signals accompanying volcanic degassing bursts at Popocatépetl is analyzed in the 15–70 s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of two eruptions (23 April and 23 May 2000) representative of mild Vulcanian activity are well reproduced by...
Authors
Bernard A. Chouet, Phillip B. Dawson, Alejandra Arciniega-Ceballos
Log of Trench 04A across the Hayward Fault at Tyson's Lagoon (Tule Pond), Fremont, Alameda County, California Log of Trench 04A across the Hayward Fault at Tyson's Lagoon (Tule Pond), Fremont, Alameda County, California
This publication makes available a detailed trench log (sheets 1 and 2) of a 110-m trench we excavated in 2004 across a tectonic sag pond in the Hayward fault zone. Also included are revised stratigraphic unit descriptions from this fifth field season of subsurface investigation of the Hayward fault at Tyson's Lagoon (Tule Pond). Preliminary findings based on fieldwork done in 2000 have...
Authors
James J. Lienkaemper, Patrick L. Williams, Robert R. Sickler, Thomas E. Fumal
An efficient algorithm for double-difference tomography and location in heterogeneous media, with an application to the Kilauea volcano An efficient algorithm for double-difference tomography and location in heterogeneous media, with an application to the Kilauea volcano
Improving our understanding of crustal processes requires a better knowledge of the geometry and the position of geological bodies. In this study we have designed a method based upon double-difference relocation and tomography to image, as accurately as possible, a heterogeneous medium containing seismogenic objects. Our approach consisted not only of incorporating double difference in...
Authors
V. Monteiller, J.-L. Got, J. Virieux, P. Okubo
The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis
Calcite is frequently cited as a source of excess Ca, Sr and alkalinity in solutes discharging from silicate terrains yet, no previous effort has been made to assess systematically the overall abundance, composition and petrogenesis of accessory calcite in granitoid rocks. This study addresses this issue by analyzing a worldwide distribution of more than 100 granitoid rocks. Calcite is...
Authors
A. F. White, M. S. Schulz, J. B. Lowenstern, D.V. Vivit, T.D. Bullen
Repeating coupled earthquakes at Shishaldin Volcano, Alaska Repeating coupled earthquakes at Shishaldin Volcano, Alaska
Since it last erupted in 1999, Shishaldin Volcano, Aleutian Islands, Alaska, has produced hundreds to thousands of long-period (1-2 Hz; LP) earthquakes every day with no other sign of volcanic unrest. In 2002, the earthquakes also exhibited a short-period (4-7 Hz; SP) signal occurring between 3 and 15 s before the LP phase. Although the SP phase contains higher frequencies than the LP...
Authors
J. Caplan-Auerbach, T. Petersen
Volcán Popocatépetl, Mexico. Petrology, magma mixing, and immediate sources of volatiles for the 1994- Present eruption Volcán Popocatépetl, Mexico. Petrology, magma mixing, and immediate sources of volatiles for the 1994- Present eruption
Volcán Popocatépetl has been the site of voluminous degassing accompanied by minor eruptive activity from late 1994 until the time of writing (August 2002). This contribution presents petrological investigations of magma erupted in 1997 and 1998, including major-element and volatile (S, Cl, F, and H2O) data from glass inclusions and matrix glasses. Magma erupted from Popocatépetl is a...
Authors
J.B. Witter, V.C. Kress, C. G. Newhall
Decadal-scale change of infiltration characteristics of a tephra-mantled hillslope at Mount St Helens, Washington Decadal-scale change of infiltration characteristics of a tephra-mantled hillslope at Mount St Helens, Washington
The cataclysmic 1980 eruption of Mount St Helens radically reduced the infiltration characteristics of ∼60 000 ha of rugged terrain and dramatically altered landscape hydrology. Two decades of erosional, biogenic, cryogenic, and anthropogenic activity have modified the infiltration characteristics of much of that devastated landscape and modulated the hydrological impact of the eruption...
Authors
J. J. Major, T. Yamakoshi
Provenance and diagenesis of the evaporite-bearing Burns formation, Meridiani Planum, Mars Provenance and diagenesis of the evaporite-bearing Burns formation, Meridiani Planum, Mars
Impure reworked evaporitic sandstones, preserved on Meridiani Planum, Mars, are mixtures of roughly equal amounts of altered siliciclastic debris, of basaltic provenance (40 ± 10% by mass), and chemical constituents, dominated by evaporitic minerals (jarosite, Mg-, Ca-sulfates ± chlorides ± Fe-, Na-sulfates), hematite and possibly secondary silica (60 ± 10%). These chemical constituents...
Authors
S. M. McLennan, J.F. Bell, W. M. Calvin, P. R. Christensen, B. C. Clark, P.A. de Souza, J. Farmer, W. H. Farrand, D.A. Fike, Ralf Gellert, A. Ghosh, T.D. Glotch, J.P. Grotzinger, B. Hahn, Kenneth E. Herkenhoff, J.A. Hurowitz, J. R. Johnson, S.S. Johnson, B. Jolliff, G. Klingelhofer, A.H. Knoll, Z. Learner, M. C. Malin, H.Y. McSween, J. Pocock, S. W. Ruff, Laurence A. Soderblom, S. W. Squyres, N.J. Tosca, W.A. Watters, M.B. Wyatt, A. Yen
Physical and chemical properties of submarine basaltic rocks from the submarine flanks of the Hawaiian Islands Physical and chemical properties of submarine basaltic rocks from the submarine flanks of the Hawaiian Islands
To evaluate physical and chemical diversity in submarine basaltic rocks, approximately 280 deep submarine samples recovered by submersibles from the underwater flanks of the Hawaiian Islands were analyzed and compared. Based on observations from the submersibles and hand specimens, these samples were classified into three main occurrence types (lavas, coarse-grained volcaniclastic rocks...
Authors
Hisayoshi Yokose, Peter W. Lipman, Toshiya Kanamatsu
Wagon loads of sand blows in White County, Illinois Wagon loads of sand blows in White County, Illinois
Several anecdotal accounts provide compelling evidence that liquefaction occurred at several sites in Illinois during the 1811-1812 New Madrid sequence, as much as 250 km north of the New Madrid seismic zone (NMSZ). At one Wabash Valley location, sand blows are still evident near Big Prairie, Illinois, a location described in a particularly detailed and precise historic account. This...
Authors
Susan E. Hough, Roger Bilham, Karl Mueller, William Stephenson, Robert Williams, Jack Odum
An assessment of volcanic threat and monitoring capabilities in the United States: Framework for a National Volcano Early Warning System An assessment of volcanic threat and monitoring capabilities in the United States: Framework for a National Volcano Early Warning System
Executive Summary NVEWS – a National Volcano Early Warning System – is being formulated by the Consortium of U.S. Volcano Observatories (CUSVO) to establish a proactive, fully integrated, national-scale monitoring effort that ensures the most threatening volcanoes in the United States are properly monitored in advance of the onset of unrest and at levels commensurate with the threats...
Authors
John W. Ewert, Marianne Guffanti, Thomas L. Murray
Geology and tsunamigenic potential of submarine landslides in Santa Barbara Channel, Southern California Geology and tsunamigenic potential of submarine landslides in Santa Barbara Channel, Southern California
A large submarine landslide complex and four small landslides developed under the Santa Barbara Channel, suggesting a potential hazard from landslide-generated tsunamis. We integrate offshore stratigraphy and geologic structure, multibeam bathymetric information, and several kinds of seismic-reflection data to understand how and when the submarine landslides formed. Seismic-reflection...
Authors
M. A. Fisher, W. R. Normark, H. Gary Greene, H.J. Lee, R. W. Sliter