Publications
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Source modeling of the 2015 Mw 7.8 Nepal (Gorkha) earthquake sequence: Implications for geodynamics and earthquake hazards Source modeling of the 2015 Mw 7.8 Nepal (Gorkha) earthquake sequence: Implications for geodynamics and earthquake hazards
The Gorkha earthquake on April 25th, 2015 was a long anticipated, low-angle thrust-faulting event on the shallow décollement between the India and Eurasia plates. We present a detailed multiple-event hypocenter relocation analysis of the Mw 7.8 Gorkha Nepal earthquake sequence, constrained by local seismic stations, and a geodetic rupture model based on InSAR and GPS data. We integrate...
Authors
Daniel E. McNamara, William L. Yeck, William D. Barnhart, V. Schulte-Pelkum, E. Bergman, L. B. Adhikari, Amod Dixit, S. E. Hough, Harley M. Benz, Paul S. Earle
Chemistry of diagenetic features analyzed by ChemCam at Pahrump Hills, Gale crater, Mars Chemistry of diagenetic features analyzed by ChemCam at Pahrump Hills, Gale crater, Mars
The Curiosity rover's campaign at Pahrump Hills provides the first analyses of lower Mount Sharp strata. Here we report ChemCam elemental composition of a diverse assemblage of post-depositional features embedded in, or cross-cutting, the host rock. ChemCam results demonstrate their compositional diversity, especially compared to the surrounding host rock: (i) Dendritic aggregates and...
Authors
Marion Nachon, Nicolas Mangold, Olivier Forni, Linda C. Kah, Agnes Cousin, Roger C. Wiens, Ryan B. Anderson, Diana L. Blaney, Jen G. Blank, Fred J. Calef, Samuel M. Clegg, Cecile Fabre, Martin R. Fisk, Olivier Gasnault, John P. Grotzinger, Rachel Kronyak, Nina L. Lanza, Jeremie Lasue, Laetitia Le Deit, Stephane Le Mouelic, Sylvestre Maurice, Pierre-Yves Meslin, D. Z. Oehler, Valerie Payre, William Rapin, Susanne Schroder, Katherine M. Stack, Dawn Sumner
Improved accuracy in quantitative laser-induced breakdown spectroscopy using sub-models Improved accuracy in quantitative laser-induced breakdown spectroscopy using sub-models
Accurate quantitative analysis of diverse geologic materials is one of the primary challenges faced by the Laser-Induced Breakdown Spectroscopy (LIBS)-based ChemCam instrument on the Mars Science Laboratory (MSL) rover. The SuperCam instrument on the Mars 2020 rover, as well as other LIBS instruments developed for geochemical analysis on Earth or other planets, will face the same...
Authors
Ryan B. Anderson, Samuel M. Clegg, Jens Frydenvang, Roger C. Wiens, Scott M. McLennan, Richard V. Morris, Bethany L. Ehlmann, M. Darby Dyar
Electrical resistivity investigation of fluvial geomorphology to evaluate potential seepage conduits to agricultural lands along the San Joaquin River, Merced County, California, 2012–13 Electrical resistivity investigation of fluvial geomorphology to evaluate potential seepage conduits to agricultural lands along the San Joaquin River, Merced County, California, 2012–13
Increased flows in the San Joaquin River, part of the San Joaquin River Restoration Program, are designed to help restore fish populations. However, increased seepage losses could result from these higher restoration flows, which could exacerbate existing drainage problems in neighboring agricultural lands and potentially damage crops. Channel deposits of abandoned river meanders that...
Authors
Krishangi D. Groover, Matthew K. Burgess, James F. Howle, Steven P. Phillips
Relations between some horizontal‐component ground‐motion intensity measures used in practice Relations between some horizontal‐component ground‐motion intensity measures used in practice
Various measures using the two horizontal components of recorded ground motions have been used in a number of studies that derive ground‐motion prediction equations and construct maps of shaking intensity. We update relations between a number of these measures, including those in Boore et al. (2006) and Boore (2010), using the large and carefully constructed global database of ground...
Authors
David Boore, Tadahiro Kishida
Paleoseismic potential of sublacustrine landslide records in a high-seismicity setting (south-central Alaska) Paleoseismic potential of sublacustrine landslide records in a high-seismicity setting (south-central Alaska)
Sublacustrine landslide stratigraphy is considered useful for quantitative paleoseismology in low-seismicity settings. However, as the recharging of underwater slopes with sediments is one of the factors that governs the recurrence of slope failures, it is not clear if landslide deposits can provide continuous paleoseismic records in settings of frequent strong shaking. To test this, we...
Authors
Nore Praet, Jasper Moernaut, Maarten Van Daele, Evelien Boes, Peter J. Haeussler, Michael Strupler, Sabine Schmidt, Michael G. Loso, Marc De Batist
Ground motion in the presence of complex Topography II: Earthquake sources and 3D simulations Ground motion in the presence of complex Topography II: Earthquake sources and 3D simulations
Eight seismic stations were placed in a linear array with a topographic relief of 222 m over Mission Peak in the east San Francisco Bay region for a period of one year to study topographic effects. Seventy‐two well‐recorded local earthquakes are used to calculate spectral amplitude ratios relative to a reference site. A well‐defined fundamental resonance peak is observed with individual...
Authors
Stephen H. Hartzell, Leonardo Ramirez-Guzman, Mark Meremonte, Alena L. Leeds
Modeling strong‐motion recordings of the 2010 Mw 8.8 Maule, Chile, earthquake with high stress‐drop subevents and background slip Modeling strong‐motion recordings of the 2010 Mw 8.8 Maule, Chile, earthquake with high stress‐drop subevents and background slip
Strong‐motion recordings of the Mw 8.8 Maule earthquake were modeled using a compound rupture model consisting of (1) a background slip distribution with large correlation lengths, relatively low slip velocity, and long peak rise time of slip of about 10 s and (2) high stress‐drop subevents (asperities) on the deeper portion of the rupture with moment magnitudes 7.9–8.2, high slip...
Authors
Arthur D. Frankel
Dynamic strains for earthquake source characterization Dynamic strains for earthquake source characterization
Strainmeters measure elastodynamic deformation associated with earthquakes over a broad frequency band, with detection characteristics that complement traditional instrumentation, but they are commonly used to study slow transient deformation along active faults and at subduction zones, for example. Here, we analyze dynamic strains at Plate Boundary Observatory (PBO) borehole...
Authors
Andrew J. Barbour, Brendan W. Crowell
Tidal triggering of earthquakes suggests poroelastic behavior on the San Andreas Fault Tidal triggering of earthquakes suggests poroelastic behavior on the San Andreas Fault
Tidal triggering of earthquakes is hypothesized to provide quantitative information regarding the fault's stress state, poroelastic properties, and may be significant for our understanding of seismic hazard. To date, studies of regional or global earthquake catalogs have had only modest successes in identifying tidal triggering. We posit that the smallest events that may provide...
Authors
Andrew Delorey, Nicholas van der Elst, Paul Johnson
Development and utilization of USGS ShakeCast for rapid post-earthquake assessment of critical facilities and infrastructure Development and utilization of USGS ShakeCast for rapid post-earthquake assessment of critical facilities and infrastructure
The ShakeCast system is an openly available, near real-time post-earthquake information management system. ShakeCast is widely used by public and private emergency planners and responders, lifeline utility operators and transportation engineers to automatically receive and process ShakeMap products for situational awareness, inspection priority, or damage assessment of their own...
Authors
David J. Wald, Kuo-wan Lin, C. A. Kircher, Kishor S. Jaiswal, Nico Luco, L. Turner, Daniel Slosky
Compartmentalization of the Coso East Flank geothermal field imaged by 3-D full-tensor MT inversion Compartmentalization of the Coso East Flank geothermal field imaged by 3-D full-tensor MT inversion
Previous magnetotelluric (MT) studies of the high-temperature Coso geothermal system in California identified a subvertical feature of low resistivity (2–5 Ohm m) and appreciable lateral extent (>1 km) in the producing zone of the East Flank field. However, these models could not reproduce gross 3-D effects in the recorded data. We perform 3-D full-tensor inversion and retrieve a...
Authors
Nathaniel J. Lindsey, J. Ole Kaven, Nicholas C. Davatzes, Gregory A. Newman