Publications
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Seismometer records of ground tilt induced by debris flows
A change in surface loading causes the Earth’s surface to deform. Mass movements, such as debris flows, can cause a tilt large enough to be recorded by nearby instruments, but the signal is strongly dependent on the mass loading and subsurface parameters. Specifically designed sensors for such measurements (tiltmeters) are cumbersome to install. Alternatively, broadband seismometers record transla
Authors
Michaela Wenner, Kate E. Allstadt, Weston Thelen, Andrew Lockhart, Jacob Hirschberg, Brian W. McArdell, Fabian Walter
Stress heterogeneity as a driver of aseismic slip during the 2011 Prague, Oklahoma aftershock sequence
The interaction of aseismic and seismic slip before and after an earthquake is fundamental for both earthquake nucleation and postseismic stress relaxation. However, it can be difficult to determine where and when aseismic slip occurs within the seismogenic zone because geodetic techniques are limited to detecting moderate to large slip amplitudes or long duration small slip amplitudes. Here, we u
Authors
Kristina Okamoto, Heather Savage, Elizabeth S. Cochran, Katie M. Keranen
Brittle faulting at elevated temperature and vanishing effective stress
If brittle fault strength depends only on friction, slip instability is discouraged at low effective normal stress, σ. Stress drop and the critical stiffness necessary for unstable sliding both vanish with σ; small earthquakes cannot occur. Very low σ is inferred in the source region of low-frequency earthquakes (LFEs) on the San Andreas fault (SAF). Moreover, if pore pressure, p, is undrained at
Authors
Nicholas M. Beeler
The distribution of clay minerals and their impact on diagenesis in Glen Torridon, Gale crater, Mars
Glen Torridon (GT) is a recessive-trough feature on the northwestern slope of “Mt. Sharp” in Gale crater, Mars with the highest Fe-/Mg-phyllosilicates abundances detected by the Curiosity rover to date. Understanding the origin of these clay minerals and their relationship with diagenetic processes is critical for reconstructing the nature and habitability of past surface and subsurface environmen
Authors
Amanda Rudolph, Briony H. N. Horgan, Jeffrey B. Johnson, Kristen A. Bennett, James Haber, James F. Bell, V. F. Fox, Samantha Jacob, S. Maurice, Elizabeth B. Rampe, Melissa Rice, Christina Seeger, Roger C. Wiens
Sedimentological and geochemical perspectives on a marginal lake environment recorded in the Hartmann’s Valley and Karasburg members of the Murray formation, Gale crater, Mars
This study utilizes instruments from the Curiosity rover payload to develop an integrated paleoenvironmental and compositional reconstruction for the 65-m thick interval of stratigraphy comprising the Hartmann's Valley and Karasburg members of the Murray formation, Gale crater, Mars. The stratigraphy consists of cross-stratified sandstone (Facies 1), planar-laminated sandstone (Facies 2), and plan
Authors
Samantha Gwizd, Christopher M. Fedo, John P. Grotzinger, Steven G. Banham, Frances Rivera-Hernandez, Kathryn M. Stack, Kirsten L. Siebach, Michael T. Thorpe, Lucy Thompson, Catherine O'Connell-Cooper, Nathan Stein, Lauren A. Edgar, Sanjeev Gupta, David M. Rubin, Dawn Sumner, Ashwin R. Vasavada
Introduction to the special issue of the Consortium of Organizations for Strong Motion Observation Systems (COSMOS) international guidelines for applying noninvasive geophysical techniques to characterize seismic site conditions
Knowledge about local seismic site conditions provides critical information to account for site effects that are commonly observed in strong motion recordings. Certainly, other wave propagation effects can influence these observations, which are attributable to variations in material properties of the paths traveled by the waves, as well as the characteristics of the seismic source. However, local
Authors
Alan Yong, Aysegul Askan, John Cassidy, Sebastiano D'Amico, Stefano Parolai, Marco Pilz, William J. Stephenson
Diatom influence on the production characteristics of hydrate-bearing sediments: Examples from Ulleung Basin, offshore South Korea
The Ulleung Basin Gas Hydrate field expeditions in 2007 (UBGH1) and 2010 (UBGH2) sought to assess the Basin's gas hydrate resource potential. Coring operations in both expeditions recovered evidence of gas hydrate, primarily as fracture-filling (or vein type) morphologies in mainly silt-sized, fine-grained sediment, but also as pore-occupying hydrate in the coarser-grained layers of interbedded sa
Authors
Junbong Jang, William F. Waite, Laura A. Stern, Joo Yong Lee
Flexible multimethod approach for seismic site characterization
We describe the flexible multimethod seismic site characterization technique for obtaining shear-wave velocity (VS) profiles and derivative information, such as the time-averaged VS of the upper 30 m (VS30). Simply stated, the multimethod approach relies on the application of multiple independent noninvasive site characterization acquisition and analysis techniques utilized in a flexible field-bas
Authors
William J. Stephenson, Alan Yong, Antony Martin
Beyond the teleseism: Introducing regional seismic and geodetic data into routine USGS finite‐fault modeling
The U.S. Geological Survey (USGS) National Earthquake Information Center (NEIC) routinely produces finite‐fault models following significant earthquakes. These models are spatiotemporal estimates of coseismic slip critical to constraining downstream response products such as ShakeMap ground motion estimates, Prompt Assessment of Global Earthquake for Response loss estimates, and ground failure ass
Authors
Dara Elyse Goldberg, Pablo Koch, Diego Melgar, Sebastian Riquelme, William L. Yeck
Documenting the multiple facets of a subsiding landscape from coastal cities and wetlands to the continental shelf
Land subsidence is a settling, sinking, or collapse of the land surface. In the southeastern United States, subsidence is frequently observed as sinkhole collapse in karst environments, wetland degradation and loss in coastal and other low-lying areas, and inundation of coastal urban communities. Human activities such as fluid extraction, mining, and overburden alteration can cause or exacerbate s
Authors
James G. Flocks, Eileen McGraw, John Barras, Julie Bernier, Mike Bradley, Devin L. Galloway, James Landmeyer, W. Scott McBride, Christopher Smith, Kathryn Smith, Christopher Swarzenski, Lauren Toth
By
Natural Hazards Mission Area, Water Resources Mission Area, Coastal and Marine Hazards and Resources Program, Caribbean-Florida Water Science Center (CFWSC), Lower Mississippi-Gulf Water Science Center, Ohio-Kentucky-Indiana Water Science Center, South Atlantic Water Science Center (SAWSC), St. Petersburg Coastal and Marine Science Center, Gulf of Mexico
Reproducibility and variability of earthquake subsidence estimates from saltmarshes of a Cascadia estuary
We examine fossil foraminiferal assemblages from 20 sediment cores to assess sudden relative sea-level (RSL) changes across three mud-over-peat contacts at three salt marshes in northern Humboldt Bay, California (~44.8°N, -124.2°W). We use a validated foraminiferal-based Bayesian transfer function to evaluate the variability of subsidence stratigraphy at a range of 30-6000 m across an estuary. We
Authors
Jason Scott Padgett, Simon E. Engelhart, Harvey M. Kelsey, Robert C. Witter, Niamh Cahill
Crowd-sourced SfM: Best practices for high resolution monitoring of coastal cliffs and bluffs
Structure from motion (SfM) photogrammetry is an increasingly common technique for measuring landscape change over time by deriving 3D point clouds and surface models from overlapping photographs. Traditional change detection approaches require photos that are geotagged with a differential GPS (DGPS) location, which requires expensive equipment that can limit the ability of communities and researc
Authors
Phillipe Alan Wernette, Ian M. Miller, Andrew C. Ritchie, Jonathan Warrick