Publications
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Utah's geologic and geomorphic analogs to Mars—An overview for planetary exploration
Utah offers spectacular geologic features and valuable analog environments and processes for Mars studies. Horizontal strata of the Colorado Plateau are analogous to Mars because the overprint of plate tectonics is minimal, yet the effects of strong ground motion from earthquakes or impacts are preserved in the sedimentary record. The close proximity of analog environments and lack of vegetative c
Authors
Marjorie A. Chan, Kathleen Nicoll, Jens Ormö, Chris Okubo, Goro Komatsu
Active mountain building and the distribution of core Maxillariinae species in tropical Mexico and Central America
The observation that southeastern Central America is a hotspot for orchid diversity has long been known and confirmed by recent systematic studies and checklists. An analysis of the geographic and elevation distribution demonstrates that the most widespread species of “core” Maxillariinae are all adapted to life near sea level, whereas the most narrowly endemic species are largely distributed in w
Authors
Stephen H. Kirby
Value of a dual-polarized gap-filling radar in support of southern California post-fire debris-flow warnings
A portable truck-mounted C-band Doppler weather radar was deployed to observe rainfall over the Station Fire burn area near Los Angeles, California, during the winter of 2009/10 to assist with debris-flow warning decisions. The deployments were a component of a joint NOAA–U.S. Geological Survey (USGS) research effort to improve definition of the rainfall conditions that trigger debris flows from s
Authors
David P. Jorgensen, Maiana N. Hanshaw, Kevin M. Schmidt, Jayme L. Laber, Dennis M. Staley, Jason W. Kean, Pedro J. Restrepo
The role of adsorbed water on the friction of a layer of submicron particles
Anomalously low values of friction observed in layers of submicron particles deformed in simple shear at high slip velocities are explained as the consequence of a one nanometer thick layer of water adsorbed on the particles. The observed transition from normal friction with an apparent coefficient near μ = 0.6 at low slip speeds to a coefficient near μ = 0.3 at higher slip speeds is attributed to
Authors
Charles G. Sammis, David A. Lockner, Ze’ev Reches
High-frequency Born synthetic seismograms based on coupled normal modes
High-frequency and full waveform synthetic seismograms on a 3-D laterally heterogeneous earth model are simulated using the theory of coupled normal modes. The set of coupled integral equations that describe the 3-D response are simplified into a set of uncoupled integral equations by using the Born approximation to calculate scattered wavefields and the pure-path approximation to modulate the pha
Authors
Fred F. Pollitz
Hydrologic conditions and terrestrial laser scanning of post-firedebris flows in the San Gabriel Mountains, CA, U.S.A
To investigate rainfall-runoff conditions that generate post-wildfire debris flows, we instrumented and surveyed steep, small watersheds along the tectonically active front of the San Gabriel Mountains, California. Fortuitously, we recorded runoff-generated debris-flows triggered by one spatially restricted convective event with 28 mm of rainfall falling over 62 minutes. Our rain gages, nested hil
Authors
K. M. Schmidt, M. N. Hanshaw, J. F. Howle, J. W. Kean, Dennis M. Staley, J. D. Stock, W. Bawdeng
Seismicity of the Earth 1900-2010 Mexico and vicinity
Mexico, located in one of the world's most seismically active regions, lies on three large tectonic plates: the North American plate, Pacific plate, and Cocos plate. The relative motion of these tectonic plates causes frequent earthquakes and active volcanism and mountain building. Mexico's most seismically active region is in southern Mexico where the Cocos plate is subducting northwestward benea
Authors
Susan Rhea, Richard L. Dart, Antonio H. Villaseñor, Gavin P. Hayes, Arthur C. Tarr, Kevin P. Furlong, Harley M. Benz
Europa awakening
Brines percolating in the icy crust of Jupiter's moon Europa may be responsible for the satellite's enigmatic chaotic terrains. A new model predicts that one such terrain is currently forming over shallow subsurface water.
Authors
Laszlo P. Keszthelyi
Recent faulting in western Nevada revealed by multi-scale seismic reflection
The main goal of this study is to compare different reflection methods used to image subsurface structure within different physical environments in western Nevada. With all the methods employed, the primary goal is fault imaging for structural information toward geothermal exploration and seismic hazard estimation. We use seismic CHIRP (a swept-frequency marine acquisition system), weight drop (an
Authors
Roxanna N. Frary, John N. Louie, William J. Stephenson, Jackson K. Odum, Annie Kell, Amy Eisses, Graham M. Kent, Neal W. Driscoll, Robert Karlin, Robert L. Baskin, Satish Pullammanappallil, Lee M. Liberty
Regional geomorphology and history of Titan's Xanadu province
Titan’s enigmatic Xanadu province has been seen in some detail with instruments from the Cassini spacecraft. The region contains some of the most rugged, mountainous terrain on Titan, with relief over 2000 m. Xanadu contains evolved and integrated river channels, impact craters, and dry basins filled with smooth, radar-dark material, perhaps sediments from past lake beds. Arcuate and aligned mount
Authors
J. Radebaugh, R. D. Lorenz, S. D. Wall, R. L. Kirk, C. A. Wood, J. I. Lunine, E. R. Stofan, R M.C. Lopes, P. Valora, T.G. Farr, A. Hayes, B. Stiles, Giuseppe Mitri, H. Zebker, M. Janssen, L. Wye, A. LeGall, K. L. Mitchell, F. Paganelli, R.D. West, E.L. Schaller
Constraints on the long‐period moment‐dip tradeoff for the Tohoku earthquake
Since the work of Kanamori and Given (1981), it has been recognized that shallow, pure dip‐slip earthquakes excite long‐period surface waves such that it is difficult to independently constrain the moment (M0) and the dip (δ) of the source mechanism, with only the product M0 sin(2δ) being well constrained. Because of this, it is often assumed that the primary discrepancies between the moments of s
Authors
Victor C. Tsai, Gavin P. Hayes, Zacharie Duputel
Preface to the Focused Issue on the 22 February 2011 Magnitude 6.2 Christchurch Earthquake
The 22 February 2011 magnitude 6.2 Christchurch earthquake, centered southeast of Christchurch, was part of the aftershock sequence that has been occurring since the September 2010 magnitude 7.1 quake near Darfield, 40 km west of the city. The Christchurch earthquake killed more than 180 people, damaged or destroyed more than 100,000 buildings, and is New Zealand's most deadly disaster since the e
Authors
Erol Kalkan