Publications
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Introduction to the focus section on the 2015 Gorkha, Nepal, earthquake
It has long been recognized that Nepal faces high earthquake hazard, with the most recent large (Mw>7.5) events in 1833 and 1934. When the 25 April 2015Mw 7.8 Gorkha earthquake struck, it appeared initially to be a realization of worst fears. In spite of its large magnitude and proximity to the densely populated Kathmandu valley, however, the level of damage was lower than anticipated, with most v
Authors
Susan E. Hough
Limited role for thermal erosion by turbulent lava in proximal Athabasca Valles, Mars
The Athabasca Valles flood lava is among the most recent (<50 Ma) and best preserved effusive lava flows on Mars and was probably emplaced turbulently. The Williams et al. (2005) model of thermal erosion by lava has been applied to what we term “proximal Athabasca,” the 75 km long upstream portion of Athabasca Valles. For emplacement volumes of 5000 and 7500 km3and average flow thicknesses of 20 a
Authors
Vincenzo Cataldo, David A. Williams, Colin M. Dundas, Laszlo P. Kestay
Reactivated faulting near Cushing, Oklahoma: Increased potential for a triggered earthquake in an area of United States strategic infrastructure
In October 2014 two moderate-sized earthquakes (Mw 4.0 and 4.3) struck south of Cushing, Oklahoma, below the largest crude oil storage facility in the world. Combined analysis of the spatial distribution of earthquakes and regional moment tensor focal mechanisms indicate reactivation of a subsurface unnamed and unmapped left-lateral strike-slip fault. Coulomb failure stress change calculations usi
Authors
Daniel E. McNamara, Gavin P. Hayes, Harley M. Benz, Robert Williams, Nicole D McMahon, R.C. Aster, Austin F. Holland, T Sickbert, Robert B. Herrmann, Richard W. Briggs, Gregory M. Smoczyk, Eric Bergman, Paul S. Earle
Validation of meter-scale surface faulting offset measurements from high-resolution topographic data
Studies of active fault zones have flourished with the availability of high-resolution topographic data, particularly where airborne light detection and ranging (lidar) and structure from motion (SfM) data sets provide a means to remotely analyze submeter-scale fault geomorphology. To determine surface offset at a point along a strike-slip earthquake rupture, geomorphic features (e.g., stream chan
Authors
Barrett Salisbury, D.E. Haddad, T. K. Rockwell, R. Arrowsmith, C. Madugo, O. Zielke, Katherine M. Scharer
A random-walk algorithm for modeling lithospheric density and the role of body forces in the evolution of the Midcontinent Rift
This paper develops a Monte Carlo algorithm for extracting three-dimensional lithospheric density models from geophysical data. Empirical scaling relationships between velocity and density create a 3D starting density model, which is then iteratively refined until it reproduces observed gravity and topography. This approach permits deviations from uniform crustal velocity-density scaling, which pr
Authors
William Brower Levandowski, Oliver S. Boyd, Richard W. Briggs, Ryan D. Gold
Modeling the development of martian sublimation thermokarst landforms
Sublimation-thermokarst landforms result from collapse of the surface when ice is lost from the subsurface. On Mars, scalloped landforms with scales of decameters to kilometers are observed in the mid-latitudes and considered likely thermokarst features. We describe a landscape evolution model that couples diffusive mass movement and subsurface ice loss due to sublimation. Over periods of tens of
Authors
Colin M. Dundas, Shane Byrne, Alfred S. McEwen
Using a modified time-reverse imaging technique to locate low-frequency earthquakes on the San Andreas Fault near Cholame, California
We present a new method to locate low-frequency earthquakes (LFEs) within tectonic tremor episodes based on time-reverse imaging techniques. The modified time-reverse imaging technique presented here is the first method that locates individual LFEs within tremor episodes within 5 km uncertainty without relying on high-amplitude P-wave arrivals and that produces similar hypocentral locations to met
Authors
Tobias Horstmann, Rebecca M. Harrington, Elizabeth S. Cochran
Identifying block structure in the Pacific Northwest, USA
We have identified block structure in the Pacific Northwest (west of 116°W between 38°N and 49°N) by clustering GPS stations so that the same Euler vector approximates the velocity of each station in a cluster. Given the total number k of clusters desired, the clustering procedure finds the best assignment of stations to clusters. Clustering is calculated for k= 2 to 14. In geographic space, clust
Authors
James C. Savage, Ray E. Wells
Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars
The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin
Authors
J.P. Grotzinger, S. Gupta, M. C. Malin, D. M. Rubin, J. Schieber, K. Siebach, D.Y. Sumner, K.M. Stack, A.R. Vasavada, R.E. Arvidson, F. Calef, Lauren A. Edgar, W. F. Fischer, J.A. Grant, J.L. Griffes, L.C. Kah, M.P. Lamb, K.W. Lewis, N. Mangold, M.E. Minitti, M.C. Palucis, M. Rice, R.M.E. Williams, R.A. Yingst, D. Blake, D. Blaney, P. Conrad, J.A. Crisp, W. E. Dietrich, G. Dromart, K.S. Edgett, R.C. Ewing, R. Gellert, J.A. Hurowitz, G. Kocurek, P.G. Mahaffy, M.J. McBride, S. M. McLennan, M.A. Mischna, D. Ming, R.E. Milliken, H. Newsom, D. Oehler, T. J. Parker, D. Vaniman, R. C. Wiens, S. A. Wilson
Borehole strainmeter measurements spanning the 2014, Mw6.0 South Napa Earthquake, California: The effect from instrument calibration
The 24 August 2014 Mw6.0 South Napa, California earthquake produced significant offsets on 12 borehole strainmeters in the San Francisco Bay area. These strainmeters are located between 24 and 80 km from the source and the observed offsets ranged up to 400 parts-per-billion (ppb), which exceeds their nominal precision by a factor of 100. However, the observed offsets of tidally calibrated strains
Authors
John O. Langbein
The Iquique earthquake sequence of April 2014: Bayesian modeling accounting for prediction uncertainty
The subduction zone in northern Chile is a well-identified seismic gap that last ruptured in 1877. On 1 April 2014, this region was struck by a large earthquake following a two week long series of foreshocks. This study combines a wide range of observations, including geodetic, tsunami, and seismic data, to produce a reliable kinematic slip model of the Mw=8.1 main shock and a static slip model of
Authors
Zacharie Duputel, Junle Jiang, Romain Jolivet, Mark Simons, Luis Rivera, Jean-Paul Ampuero, Bryan Riel, Susan E Owen, Angelyn W Moore, Sergey V Samsonov, Francisco Ortega Culaciati, Sarah E. Minson
Ground motion-simulations of 1811-1812 New Madrid earthquakes, central United States
We performed a suite of numerical simulations based on the 1811–1812 New Madrid seismic zone (NMSZ) earthquakes, which demonstrate the importance of 3D geologic structure and rupture directivity on the ground‐motion response throughout a broad region of the central United States (CUS) for these events. Our simulation set consists of 20 hypothetical earthquakes located along two faults associated w
Authors
L. Ramirez-Guzman, Robert Graves, Kim Olsen, Oliver S. Boyd, Chris H. Cramer, Stephen H. Hartzell, Sidao Ni, Paul G. Somerville, Robert Williams, Jinquan Zhong