Jacob I Walter

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Dynamics of marine-terminating major outlet glaciers are of high interest because of their potential for drawing down large areas of the Greenland ice sheet. We quantify short-term changes in ice flow speed and calving at a major West Greenland glacier and examine their relationship to the presence of the sea-ice melange and tidal stage. A field campaign at(More)
[1] Bidaily, tidally modulated stick‐slip speed‐ups of the Whillans Ice Plain (WIP) provide insight into glacier dynamics and failure at a naturally repeating fault asperity. We installed a network of continuously operating GPS receivers in 2007 and deployed on‐ice broadband seismometers during the austral summer of 2008 on Whillans Ice Stream (WIS), West(More)
Subglacial discharge influences glacier basal motion and erodes and redeposits sediment. At tidewater glacier termini, discharge drives submarine terminus melting, affects fjord circulation, and is a central component of proglacial marine ecosystems. However, our present inability to track subglacial discharge and its variability significantly hinders our(More)
The state of Oklahoma has experienced an unprecedented increase in earthquake activity since 2009, likely driven by large-scale wastewater injection operations. Statewide injection rates peaked in early 2015 and steadily decreased thereafter, approximately coinciding with collapsing oil prices and regulatory action. If seismic activity is primarily driven(More)
In Texas, earthquakes have occurred in close association with activities accompanying petroleum production since 1925. Here we develop a five-question test to categorize individual events as “tectonic,” “possibly induced,” “probably induced,” or “almost certainly induced.” In Texas, the probably induced and almost certainly induced earthquakes are broadly(More)
Water that pressurizes the base of glaciers and ice sheets enhances glacier velocities and modulates glacial erosion. Predicting ice flow and erosion therefore requires knowledge of subglacial channel evolution, which remains observationally limited. Here we demonstrate that detailed analysis of seismic ground motion caused by subglacial water flow at(More)
The state of Oklahoma has experienced an unprecedented increase in earthquake activity since 2009, likely driven by large-scale wastewater injection operations. Statewide injection rates peaked in early 2015 and steadily decreased thereafter, approximately coinciding with collapsing oil prices and regulatory action. If seismic activity is primarily driven(More)
The Pawnee M5.8 earthquake is the largest event in Oklahoma instrument recorded history. It occurred near the edge of active seismic zones, similar to other M5+ earthquakes since 2011. It ruptured a previously unmapped fault and triggered aftershocks along a complex conjugate fault system. With a high-resolution earthquake catalog, we observe propagating(More)
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