Publications
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Morphological indicators of a mascon beneath Ceres' largest crater, Kerwan
Gravity data of Ceres returned by the National Aeronautics and Space Administration's Dawn spacecraft is consistent with a lower density crust of variable thickness overlying a higher density mantle. Crustal thickness variations can affect the long‐term, postimpact modification of impact craters on Ceres. Here we show that the unusual morphology of the 280 km diameter crater Kerwan may result from
Authors
Michael T. Bland, Anton Ermakov, Carol A. Raymond, David A. Williams, Tim J. Bowling, F. Preusker, Ryan S. Park, Simone Marchi, Julie C. Castillo-Rogez, R.R. Fu, Christopher T. Russell
Image simulation and assessment of the colour and spatial capabilities of the Colour and Stereo Surface Imaging System (CaSSIS) on the ExoMars Trace Gas Orbiter
This study aims to assess the spatial and visible/near-infrared (VNIR) colour/spectral capabilities of the 4-band Colour and Stereo Surface Imaging System (CaSSIS) aboard the ExoMars 2016 Trace Grace Orbiter (TGO). The instrument response functions for the CaSSIS imager was used to resample spectral libraries, modelled spectra and to construct spectrally (i.e., in I/F space) and spatially consiste
Authors
Livio L. Tornabene, Frank P. Seelos, Antoine Pommerol, Nicolas Thomas, Christy M. Caudill, Patricio Becerra, John C. Bridges, Shane Byrne, Marco Cardinale, Matthew Chojnacki, Susan J. Conway, Gabriele Cremonese, Colin M. Dundas, M. R. El-Maarry, Jennifer Fernando, Candice J. Hansen, Kayle Hansen, Tanya N. Harrison, Rachel Henson, Lucia Marinangeli, Alfred S. McEwen, Maurizio Pajola, Sarah S. Sutton, James J. Wray
Testing earthquake links in Mexico from 1978 up to the 2017 M=8.1 Chiapas and M=7.1 Puebla shocks
The M = 8.1 Chiapas and the M = 7.1 Puebla earthquakes occurred in the bending part of the subducting Cocos plate 11 days and ~600 km apart, a range that puts them well outside the typical aftershock zone. We find this to be a relatively common occurrence in Mexico, with 14% of M > 7.0 earthquakes since 1900 striking more than 300 km apart and within a 2 week interval, not different from a randomi
Authors
Margarita Segou, Thomas E. Parsons
Irregular focal mechanisms observed at Salton Sea Geothermal Field: Possible influences of anthropogenic stress perturbations
At the Salton Sea Geothermal Field (SSGF), strain accumulation is released through seismic slip and aseismic deformation. Earthquake activity at the SSGF often occurs in swarm-like clusters, some with clear migration patterns. We have identified an earthquake sequence composed entirely of focal mechanisms representing an ambiguous style of faulting, where strikes are similar but deformation occurs
Authors
Aren Crandall-Bear, Andrew J. Barbour, Martin Schoenball
Planetary dune workshop expands to include subaqueous processes
Dune-like structures appear in the depths of Earth’s oceans, across its landscapes, and in the extremities of the solar system beyond. Dunes rise up under the thick dense atmosphere of Venus, and they have been found under the almost unimaginably ephemeral atmosphere of a comet.
Authors
Timothy N. Titus, Gerald Bryant, David M. Rubin
Seismic hazard, risk, and design for South America
We calculate seismic hazard, risk, and design criteria across South America using the latest data, models, and methods to support public officials, scientists, and engineers in earthquake risk mitigation efforts. Updated continental scale seismic hazard models are based on a new seismicity catalog, seismicity rate models, evaluation of earthquake sizes, fault geometry and rate parameters, and grou
Authors
Mark D. Petersen, Stephen Harmsen, Kishor S. Jaiswal, Kenneth S. Rukstales, Nicolas Luco, Kathleen Haller, Charles Mueller, Allison Shumway
Earthquake potential in California-Nevada implied by correlation of strain rate and seismicity
Rock mechanics studies and dynamic earthquake simulations show that patterns of seismicity evolve with time through (1) accumulation phase, (2) localization phase, and (3) rupture phase. We observe a similar pattern of changes in seismicity during the past century across California and Nevada. To quantify these changes, we correlate GPS strain rates with seismicity. Earthquakes of M > 6.5 are coll
Authors
Yuehua Zeng, Mark D. Petersen, Zheng-Kang Shen
Chirp subbottom profile data collected in 2015 from the northern Chandeleur Islands, Louisiana
As part of the Barrier Island Evolution Research project, scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center conducted a nearshore geophysical survey around the northern Chandeleur Islands, Louisiana, in September 2015. The objective of the project is to improve the understanding of barrier island geomorphic evolution, particularly storm-related depo
Authors
Arnell S. Forde, Nancy T. DeWitt, Jake J. Fredericks, Jennifer L. Miselis
Geoelectric hazard maps for the Mid-Atlantic United States: 100 year extreme values and the 1989 magnetic storm
Maps of extreme value geoelectric field amplitude are constructed for the Mid‐Atlantic United States, a region with high population density and critically important power grid infrastructure. Geoelectric field time series for the years 1983–2014 are estimated by convolving Earth surface impedances obtained from 61 magnetotelluric survey sites across the Mid‐Atlantic with historical 1 min (2 min Ny
Authors
Jeffrey J. Love, Greg M. Lucas, Anna Kelbert, Paul A. Bedrosian
Revised recommended methods for analyzing crater size-frequency distributions
Impact crater populations crucially help us to understand solar system dynamics, planetary surface histories, and surface modification processes. A single previous effort to standardize how crater data are displayed in graphs, tables, and archives, was in a 1978 NASA report by the Crater Analysis Techniques Working Group, published in 1979 in Icarus. The report had a significant lasting effect, bu
Authors
Stuart J. Robbins, Jamie D. Riggs, Brian P. Weaver, Edward B. Bierhaus, Clark R. Chapman, Michelle R. Kirchoff, Kelsi N. Singer, Lisa Gaddis
Extreme-event geoelectric hazard maps: Chapter 9
Maps of geoelectric amplitude covering about half the continental United States are presented that will be exceeded, on average, once per century in response to an extreme-intensity geomagnetic disturbance. These maps are constructed using an empirical parameterization of induction: convolving latitude-dependent statistical maps of extreme-value geomagnetic disturbances, obtained from decades of 1
Authors
Jeffrey J. Love, Paul A. Bedrosian