Publications
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Rainfall-induced landslides in Puerto Rico: An overview Rainfall-induced landslides in Puerto Rico: An overview
Rainfall-induced landslides are common in Puerto Rico (PR). The presence of steep slopes in mountainous terrain, coupled with weathered soils and intense rainfall, leads to severe slope-stability problems throughout the island. Episodic triggering events such as hurricanes and earthquakes further exacerbate these problems. All physiographic provinces of the island have experienced...
Authors
M.A. Pando, M.E. Ruiz, M. C. Larsen
Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater
Gusev crater was selected as the landing site for the Spirit rover because of the possibility that it once held a lake. Thus one of the rover's tasks was to search for evidence of lake sediments. However, the plains at the landing site were found to be covered by a regolith composed of olivine-rich basaltic rock and wind-blown 'global' dust. The analyses of three rock interiors exposed...
Authors
L.A. Haskin, A. Wang, B.L. Jolliff, H.Y. McSween, B. C. Clark, D.J. Des Marais, S. M. McLennan, N.J. Tosca, J.A. Hurowitz, J.D. Farmer, A. Yen, S. W. Squyres, R. E. Arvidson, G. Klingelhofer, C. Schroder, P.A. De Souza, D. W. Ming, Ralf Gellert, J. Zipfel, J. Bruckner, J.F. Bell, Kenneth E. Herkenhoff, P. R. Christensen, S. Ruff, D. Blaney, S. Gorevan, N.A. Cabrol, L. Crumpler, J. Grant, L. Soderblom
The carbon dioxide cycle The carbon dioxide cycle
The seasonal CO2 cycle on Mars refers to the exchange of carbon dioxide between dry ice in the seasonal polar caps and gaseous carbon dioxide in the atmosphere. This review focuses on breakthroughs in understanding the process involving seasonal carbon dioxide phase changes that have occurred as a result of observations by Mars Global Surveyor.
Authors
Philip B. James, Gary B. Hansen, Timothy N. Titus
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
An alternative approach to characterize nonlinear site effects An alternative approach to characterize nonlinear site effects
This paper examines the rationale of a method of nonstationary processing and analysis, referred to as the Hilbert-Huang transform (HHT), for its application to a recording-based approach in quantifying influences of soil nonlinearity in site response. In particular, this paper first summarizes symptoms of soil nonlinearity shown in earthquake recordings, reviews the Fourier-based...
Authors
R.R. Zhang, S. Hartzell, J. Liang, Y. Hu
Interferometric synthetic aperture radar study of Okmok volcano, Alaska, 1992-2003: Magma supply dynamics and postemplacement lava flow deformation Interferometric synthetic aperture radar study of Okmok volcano, Alaska, 1992-2003: Magma supply dynamics and postemplacement lava flow deformation
Okmok volcano, located in the central Aleutian arc, Alaska, is a dominantly basaltic complex topped with a 10-km-wide caldera that formed circa 2.05 ka. Okmok erupted several times during the 20th century, most recently in 1997; eruptions in 1945, 1958, and 1997 produced lava flows within the caldera. We used 80 interferometric synthetic aperture radar (InSAR) images (interferograms) to...
Authors
Z. Lu, Timothy Masterlark, Daniel Dzurisin
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
The Zamama-Thor region of Io: Insights from a synthesis of mapping, topography, and Galileo spacecraft data The Zamama-Thor region of Io: Insights from a synthesis of mapping, topography, and Galileo spacecraft data
We have studied data from the Galileo spacecraft's three remote sensing instruments (Solid-State Imager (SSI), Near-Infrared Mapping Spectrometer (NIMS), and Photopolarimeter-Radiometer (PPR)) covering the Zamama–Thor region of Io's antijovian hemisphere, and produced a geomorphological map of this region. This is the third of three regional maps we are producing from the Galileo...
Authors
David A. Williams, Laszlo P. Keszthelyi, Paul M. Schenk, Moses P. Milazzo, Rosaly Lopes, Julie A. Rathbun, Ronald Greeley
Undersea landslides: Extent and significance in the Pacific Ocean, an update Undersea landslides: Extent and significance in the Pacific Ocean, an update
Submarine landslides are known to occur disproportionately in a limited number of environments including fjords, deltas, canyons, volcanic islands and the open continental slope. An evaluation of the progress that has been made in understanding Pacific Ocean submarine landslides over the last 15 years shows that mapping technologies have improved greatly, allowing a better interpretation...
Authors
H.J. Lee
Volcanic activity at Tvashtar Catena, Io Volcanic activity at Tvashtar Catena, Io
Galileo's Solid State Imager (SSI) observed Tvashtar Catena four times between November 1999 and October 2001, providing a unique look at a distinctive high latitude volcanic complex on Io. The first observation (orbit I25, November 1999) resolved, for the first time, an active extraterrestrial fissure eruption; the brightness temperature was at least 1300 K. The second observation...
Authors
Moses P. Milazzo, Laszlo P. Keszthelyi, Jani Radebaugh, Ashley G. Davies, Elizabeth P. Turtle, Paul E. Geissler, Kenneth P. Klaasen, Julie A. Rathbun, Alfred S. McEwen
Tilt recorded by a portable broadband seismograph: The 2003 eruption of Anatahan Volcano, Mariana Islands Tilt recorded by a portable broadband seismograph: The 2003 eruption of Anatahan Volcano, Mariana Islands
The horizontal components of broadband seismographs are highly sensitive to tilt, suggesting that commonly deployed portable broadband seismic sensors may record important tilt information associated with volcanic eruptions. We report on a tilt episode that coincides with the first historical eruption of Anatahan volcano on May 10, 2003. The tilt was recorded by a Strekheisen STS‐2...
Authors
D.A. Wiens, S.H. Pozgay, P.J. Shore, A.W. Sauter, R.A. White
Seismicity and tilt associated with the 2003 Anatahan eruption sequence Seismicity and tilt associated with the 2003 Anatahan eruption sequence
On May 10, 2003, the first historical eruption of Anatahan volcano in the western Pacific Mariana Islands was fortuitously recorded by a broadband seismograph installed on the island only 4 days prior to the eruption. This station, located 7 km WNW of the active crater, together with another broadband seismograph on Sarigan Island 45 km to the north, continued to operate throughout the 2...
Authors
S.H. Pozgay, R.A. White, D.A. Wiens, P.J. Shore, A.W. Sauter, J.L. Kaipat