Publications
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Mars exploration rover geologic traverse by the spirit rover in the plains of Gusev crater, Mars Mars exploration rover geologic traverse by the spirit rover in the plains of Gusev crater, Mars
The Spirit rover completed a 2.5 km traverse across gently sloping plains on the floor of Gusev crater from its location on the outer rim of Bonneville crater to the lower slopes of the Columbia Hills, Mars. Using the Athena suite of instruments in a transect approach, a systematic series of overlapping panoramic mosaics, remote sensing observations, surface analyses, and trenching...
Authors
L.S. Crumpler, S. W. Squyres, R. E. Arvidson, J.F. Bell, D. Blaney, N.A. Cabrol, P. R. Christensen, D.J. DesMarais, J.D. Farmer, R. Fergason, M.P. Golombek, F.D. Grant, J. A. Grant, R. Greeley, B. Hahn, Kenneth E. Herkenhoff, J.A. Hurowitz, A.T. Knudson, G. A. Landis, R. Li, J. Maki, H.Y. McSween, D. W. Ming, J.E. Moersch, M.C. Payne, J.W. Rice, L. Richter, S. W. Ruff, M. Sims, S.D. Thompson, N. Tosca, A. Wang, P. Whelley, S.P. Wright, M.B. Wyatt
THEMIS VIS and IR observations of a high-altitude Martian dust devil THEMIS VIS and IR observations of a high-altitude Martian dust devil
The Mars Odyssey Thermal Emission Imaging System (THEMIS) imaged a Martian dust devil in both visible and thermal-infrared wavelengths on January 30, 2004. We believe this is the first documented infrared observation of an extraterrestrial dust devil, and the highest to be directly observed at more than 16 kilometers above the equatorial geoid of Mars. This dust devil measured over 700...
Authors
Glen Cushing, Timothy N. Titus, Phillip R. Christensen
Source process of a long-period event at Kilauea volcano, Hawaii Source process of a long-period event at Kilauea volcano, Hawaii
We analyse a long-period (LP) event observed by a dense seismic network temporarily operated at Kilauea volcano, Hawaii, in 1996. We systematically perform spectral analyses, waveform inversions and forward modeling of the LP event to quantify its source process. Spectral analyses identify two dominant spectral frequencies at 0.6 and 1.3 Hz with associated Q values in the range 10-20...
Authors
Hiroyuki Kumagai, B. A. Chouet, P.B. Dawson
Evolution of melt-vapor surface tension in silicic volcanic systems: Experiments with hydrous melts Evolution of melt-vapor surface tension in silicic volcanic systems: Experiments with hydrous melts
We evaluate the melt‐vapor surface tension (σ) of natural, water‐saturated dacite melt at 200 MPa, 950–1055°C, and 4.8–5.7 wt % H2O. We experimentally determine the critical supersaturation pressure for bubble nucleation as a function of dissolved water and then solve for σ at those conditions using classical nucleation theory. The solutions obtained give dacite melt‐vapor surface...
Authors
M. Mangan, T. Sisson
Magma generation at a large, hyperactive silicic volcano (Taupo, New Zealand) revealed by U-Th and U-Pb systematics in zircons Magma generation at a large, hyperactive silicic volcano (Taupo, New Zealand) revealed by U-Th and U-Pb systematics in zircons
Young (
Authors
B. L. A. Charlier, C. J. N. Wilson, J. B. Lowenstern, S. Blake, P.W. van Calsteren, J.P. Davidson
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