Publications
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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
Ionospheric current source modeling and global geomagnetic induction using ground geomagnetic observatory data
Long-period global-scale electromagnetic induction studies of deep Earth conductivity are based almost exclusively on magnetovariational methods and require accurate models of external source spatial structure. We describe approaches to inverting for both the external sources and three-dimensional (3-D) conductivity variations and apply these methods to long-period (T≥1.2 days) geomagnetic observa
Authors
Jin Sun, Anna Kelbert, G. D. Egbert
Development of the Global Earthquake Model’s neotectonic fault database
The Global Earthquake Model (GEM) aims to develop uniform, openly available, standards, datasets and tools for worldwide seismic risk assessment through global collaboration, transparent communication and adapting state-of-the-art science. GEM Faulted Earth (GFE) is one of GEM’s global hazard module projects. This paper describes GFE’s development of a modern neotectonic fault database and a uniqu
Authors
Annemarie Christophersen, Nicola Litchfield, Kelvin Berryman, Richard Thomas, Roberto Basili, Laura Wallace, William Ries, Gavin P. Hayes, Kathleen M. Haller, Toshikazu Yoshioka, Richard D. Koehler, Dan Clark, Monica Wolfson-Schwehr, Margaret S. Boettcher, Pilar Villamor, Nick Horspool, Teraphan Ornthammarath, Ramon Zuñiga, Robert M. Langridge, Mark W. Stirling, Tatiana Goded, Carlos Costa, Robert Yeats
Blind identification of the Millikan Library from earthquake data considering soil–structure interaction
The Robert A. Millikan Library is a reinforced concrete building with a basement level and nine stories above the ground. Located on the campus of California Institute of Technology (Caltech) in Pasadena California, it is among the most densely instrumented buildings in the U.S. From the early dates of its construction, it has been the subject of many investigations, especially regarding soil–stru
Authors
S. F. Ghahari, F. Abazarsa, O. Avci, Mehmet Çelebi, E. Taciroglu
Hydrothermal alteration and diagenesis of terrestrial lacustrine pillow basalts: Coordination of hyperspectral imaging with laboratory measurements
We investigate an outcrop of ∼187 Ma lacustrine pillow basalts of the Talcott Formation exposed in Meriden, Connecticut, USA, focusing on coordinated analyses of one pillow lava to characterize the aqueous history of these basalts in the Hartford Basin. This work uses a suite of multidisciplinary measurements, including hyperspectral imaging, other spectroscopic techniques, and chemical and minera
Authors
Rebecca N Greenberger, John F Mustard, Edward A. Cloutis, Paul Mann, Janette H. Wilson, Roberta L Flemming, Kevin Robertson, Mark R Salvatore, Christopher Edwards
Regional seismic-wave propagation from the M5.8 23 August 2011, Mineral, Virginia, earthquake
The M5.8 23 August 2011 Mineral, Virginia, earthquake was felt over nearly the entire eastern United States and was recorded by a wide array of seismic broadband instruments. The earthquake occurred ~200 km southeast of the boundary between two distinct geologic belts, the Piedmont and Blue Ridge terranes to the southeast and the Valley and Ridge Province to the northwest. At a dominant period of
Authors
Fred Pollitz, Walter D. Mooney