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Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Glacial Earthquakes And Precursory Seismicity Associated With Thwaites Glacier Calving, J. Paul Winberry, Audrey D. Huerta, Sridhar Anandakrishnan, Richhard C. Aster, Andrew A. Nyblade, Douglas A. Wiens
Glacial Earthquakes And Precursory Seismicity Associated With Thwaites Glacier Calving, J. Paul Winberry, Audrey D. Huerta, Sridhar Anandakrishnan, Richhard C. Aster, Andrew A. Nyblade, Douglas A. Wiens
All Faculty Scholarship for the College of the Sciences
We observe two (~MS 3) long‐period (10–30 s) seismic events that originate from the terminus of Thwaites Glacier, Antarctica. Serendipitous acquisition of satellite images confirm that the seismic events were glacial earthquakes generated during the capsizing of icebergs. The glacial earthquakes were preceded by 6 days of discrete high‐frequency seismic events that can be observed at distances exceeding 250 km. The high‐frequency seismicity displays an increasing rate of occurrence, culminating in several hours of sustained tremor coeval with the long‐period events. A series of satellite images collected during this precursory time period show that the high‐frequency events and …
Slip Pulse And Resonance Of The Kathmandu Basin During The 2015 Gorkha Earthquake, Nepal, John Galetzka, Walter Szeliga
Slip Pulse And Resonance Of The Kathmandu Basin During The 2015 Gorkha Earthquake, Nepal, John Galetzka, Walter Szeliga
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Detailed geodetic imaging of earthquake ruptures enhances our understanding of earthquake physics and associated ground shaking. The 25 April 2015 moment magnitude 7.8 earthquake in Gorkha, Nepal was the first large continental megathrust rupture to have occurred beneath a high-rate (5-hertz) Global Positioning System (GPS) network. We used GPS and interferometric synthetic aperture radar data to model the earthquake rupture as a slip pulse ~20 kilometers in width, ~6 seconds in duration, and with a peak sliding velocity of 1.1 meters per second, which propagated toward the Kathmandu basin at ~3.3 kilometers per second over ~140 kilometers. The smooth slip …
Miocene - Quaternary Tectonic Evolution Of The Northern Eastern California Shear Zone, Kurt L. Frankel, Jeffrey Lee, Kim Bishop, Nancye Dawers, Plamen Ganev, Jeff Unruh, Lewis A. Owen
Miocene - Quaternary Tectonic Evolution Of The Northern Eastern California Shear Zone, Kurt L. Frankel, Jeffrey Lee, Kim Bishop, Nancye Dawers, Plamen Ganev, Jeff Unruh, Lewis A. Owen
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The northern eastern California shear zone is an important component of the Pacific– North America plate boundary. This region of active transtensional deformation east of the San Andreas fault extends from the Garlock fault northward along the east side of the Sierra Nevada and into western Nevada. The eastern California shear zone is thought to accommodate nearly a quarter of relative plate motion between the Pacific and North America plates. Recent studies in the region, utilizing innovative methods such as cosmogenic nuclide geochronology, airborne lidar, structural mapping, and (U-Th)/He geochronology, are helping elucidate deformation histories for many of the major …
Seismic Observations Of Transient Subglacial Water-Flow Beneath Macayeal Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley
Seismic Observations Of Transient Subglacial Water-Flow Beneath Macayeal Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley
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New seismic observations of harmonic tremors beneath MacAyeal Ice Stream, West Antarctica are reported. Each of the two tremor events that we recorded during a six week period had sustained arrival of 3 Hz energy for approximately 10 minutes. During that time the source location migrated a few kilometers. The harmonic nature of the tremors is interpreted as the result of resonance in subglacial water-filled cracks and conduits. The duration, monochromatic nature, and movement of the tremor indicate that the source mechanism is likely flow in the subglacial water system resulting from the discharge from a small subglacial lake. Our …
Detection Of Arbitrarily Large Dynamic Ground Motions With A Dense High-Rate Gps Network, Yehuda Bock, Linette Prawirodirdjo, Timothy I. Melbourne
Detection Of Arbitrarily Large Dynamic Ground Motions With A Dense High-Rate Gps Network, Yehuda Bock, Linette Prawirodirdjo, Timothy I. Melbourne
All Faculty Scholarship for the College of the Sciences
We describe the detection of teleseismic surface waves from the 3 November 2002 Mw 7.9 Denali fault earthquake in Alaska with a dense network of 1 Hz GPS stations in southern California, about 3900 km from the event. Relative horizontal displacements with amplitudes in excess of 15 mm and duration of 700 seconds agree with integrated velocities recorded by nearby broadband seismometers with an rms difference of 2–3 mm. The displacements are derived from independent 1 Hz instantaneous positions demonstrating that a GPS network can provide direct measurements of arbitrarily large dynamic and static ground horizontal displacements at periods longer …