Publications
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Exploring GPS observations of postseismic deformation following the 2012 MW7.8 Haida Gwaii and 2013 MW7.5 Craig, Alaska Earthquakes: Implications for viscoelastic Earth structure
The Queen Charlotte-Fairweather Fault (QC-FF) system off the coast of British Columbia and southeast Alaska is a highly active dextral strike-slip plate boundary that accommodates ∼50 mm/yr of relative motion between the Pacific and North America plates. Nine MW ≥ 6.7 earthquakes have occurred along the QC-FF system since 1910, including a MS(G-R)8.1 event in 1949. Two recent earthquakes, the Octo
Authors
Katherine A. Guns, Fred Pollitz, Thorne Lay, Han Yue
Strength recovery and sealing under hydrothermal conditions
While there is significant evidence for healing in natural faults, geothermal reservoirs, and lab experiments, the thermal, hydraulic, mechanical, and chemical interactions that influence healing are poorly understood. We present preliminary results of triaxial slide-hold-slide experiments to constrain rates and mechanisms of healing. Experiments were conducted on gouge composed of Westerly granit
Authors
Tamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. Taron
Improving ChemCam LIBS long-distance elemental compositions using empirical abundance trends
The ChemCam instrument on the Curiosity rover provides chemical compositions of Martian rocks and soils using remote laser-induced breakdown spectroscopy (LIBS). The elemental calibration is stable as a function of distance for Ti, Fe, Mg, and Ca. The calibration shows small, systematically increasing abundance trends as a function of distance for Al, Na, K, and to some extent, Si. The distance ef
Authors
Roger C. Wiens, A. J. Blazon-Brown, N. Melikechi, J. Frydenvang, E. Dehouck, S. M. Clegg, D. Delapp, Ryan Anderson, A. Cousin, S. Maurice
Creep on the Sargent Fault over the past 50 yr from alignment arrays with implications for slip transfer between the Calaveras and San Andreas Faults, California
The 55‐km‐long Sargent fault connects the creeping Calaveras fault with the locked San Andreas fault through the Santa Cruz Mountains west of Gilroy, California. The position of the Sargent fault between these two faults may have implications for slip transfer and strain accumulation between a creeping and locked fault. The detection and measurement of creep on the Sargent fault would indicate whe
Authors
Daniel Mongovin, Belle E. Philibosian
Characterizing ground motion amplification by extensive flat sediments: The seismic response of the eastern U.S. Atlantic Coastal Plain strata
We examine the effects that Atlantic Coastal Plain (ACP) strata have on ground motions in the eastern and southeastern United States. The ACP strata consist of widespread, nearly flat‐lying sediments, the upper portions of which are unconsolidated or semiconsolidated. The ACP sediments are deposited primarily on crystalline basement rocks, creating large velocity and density contrasts with the und
Authors
Thomas L. Pratt, Lisa Sue Schleicher
Further adventures in Mars DTM quality: Smoothing errors, sharpening details
We have used high-precision, high-resolution digital terrain models (DTMs) of the NASA Mars Science Laboratory (MSL) and Mars 2020 rover landing sites based on mosaicked images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (MRO HiRISE) camera as a reference data set to evaluate DTMs based on Mars Express High Resolution Stereo Camera (MEX HRSC) images. The Next Ge
Authors
Randolph L. Kirk, David Mayer, Bonnie L. Redding, Donna M. Galuszka, Robin L. Fergason, Trent M. Hare, Klaus Gwinner
Point clouds of bridge generated by terrestrial laser scanner and images via Structure from Motion technique: Comparison study
A collection of points representing an object in space is commonly called a point cloud. There are several techniques for collecting point clouds. This research is focused on a comparison study of two approaches: (1) collecting point clouds with a surveying grade terrestrial laser scanner (TLS) and (2) generating point clouds from drone-taken still images by utilizing Structure-from-Motion (SFM) t
Authors
Shakzod Takhirov, Robert E. Kayen
HydroMet: A new code for automated objective optimization of hydrometeorological thresholds for landslide initiation
Landslide detection and warning systems are important tools for mitigation of potential hazards in landslide prone areas. Traditionally, warning systems for shallow landslides have been informed by rainfall intensity-duration thresholds. More recent advances have introduced the concept of hydrometeorological thresholds that are informed not only by rainfall, but also by subsurface hydrological mea
Authors
Jacob L. Conrad, Michael D. Morphew, Rex L. Baum, Benjamin B. Mirus
An International Virtual Workshop on Global Seismology and Tectonics (IVWGST‐2020)
An International Virtual Workshop on Global Seismology and Tectonics (IVWGST‐2020) was organized by the Geoscience and Technology Division of Council of Scientific and Industrial Research—North East Institute of Science and Technology, Jorhat, India from 14 to 25 September 2020. This workshop predominantly catered to undergraduate, postgraduate, and Ph.D. students, scientists, and academicians fro
Authors
Santanu Baruah, Chandan Dey, Prachurjya Borthakur, G. Narahari Sastry, Andrew J. Michael
ShakeMap operations, policies, and procedures
The US Geological Survey’s ShakeMap is used domestically and globally for post-earthquake emergency management and response, engineering analyses, financial instruments, and other decision-making activities. Recent developments in the insurance, reinsurance, and catastrophe bond sectors link payouts of potentially hundreds of millions of dollars to ShakeMap products. Similarly, building codes, pos
Authors
David J. Wald, Charles Worden, Eric M. Thompson, Mike Hearne
New geochemical tools for investigating resource and energy functions at deep-sea cold seeps using amino-acid δ15N in chemosymbiotic mussels (Bathymodiolus childressi)
In order to reconstruct the ecosystem structure of chemosynthetic environments in the fossil record, geochemical proxies must be developed. Here, we present a suite of novel compound-specific isotope parameters for tracing chemosynthetic production with a focus on understanding nitrogen dynamics in deep-sea cold seep environments. We examined the chemosymbiotic bivalve Bathymodiolus childressi fro
Authors
Natasha Vokhshoori, Matt McCarthy, Hilary Close, Amanda Demopoulos, Nancy G. Prouty
Land-based sediment sources and transport to southwest Puerto Rico coral reefs after Hurricane Maria, May 2017 to June 2018
The effects of runoff from land on nearshore ecosystems, including coral reef communities, are influenced by both sediment supply and removal by coastal processes. Integrated studies across the land-sea interface describing sources and transport of terrestrial sediment and its nearshore fate allow reef protection initiatives to target key onshore and offshore areas. Geochemical signatures in the f
Authors
Renee K. Takesue, Clark E Sherman, Aaron O. Reyes, Olivia Cheriton, Natalia I. Ramirez, Roberto Viqueira Ríos, Curt Storlazzi