Fred F. Pollitz

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S U M M A R Y The relation between the complex geological history of the western margin of the North American plate and the processes in the mantle is still not fully documented and understood. Several pre-USArray local seismic studies showed how the characteristics of key geological features such as the Colorado Plateau and the Yellowstone Snake River(More)
The 26 December 2004 Sumatra earthquake produced static offsets at continuously operating GPS stations at distances of up to 4500 kilometers from the epicenter. We used these displacements to model the earthquake and include consideration of the Earth's shape and depth-varying rigidity. The results imply that the average slip was >5 meters along the full(More)
Two recent large earthquakes in the Mojave Desert, California-the magnitude 7.3 1992 Landers and magnitude 7.1 1999 Hector Mine earthquakes-have each been followed by elevated crustal strain rates over periods of months and years. Geodetic data collected after the Hector Mine earthquake exhibit a temporally decaying horizontal velocity field and a quadrant(More)
Large earthquakes trigger very small earthquakes globally during passage of the seismic waves and during the following several hours to days, but so far remote aftershocks of moment magnitude M ≥ 5.5 have not been identified, with the lone exception of an M = 6.9 quake remotely triggered by the surface waves from an M = 6.6 quake 4,800 kilometres away. The(More)
[1] New seismic and geodetic data from Costa Rica provide insight into seismogenic zone processes in Central America, where the Cocos and Caribbean plates converge. Seismic data are from combined land and ocean bottom deployments in the Nicoya peninsula in northern Costa Rica and near the Osa peninsula in southern Costa Rica. In Nicoya, inversion of GPS(More)
Results from different tsunami forecasting and hazard assessment models are compared with observed tsunami wave heights from the 26 December 2004 Indian Ocean tsunami. Forecast models are based on initial earthquake information and are used to estimate tsunami wave heights during propagation. An empirical forecast relationship based only on seismic moment(More)
a r t i c l e i n f o a b s t r a c t USArray has facilitated significant advancement in tomographic models and methodologies. While there persists a fundamental tradeoff between horizontal and vertical resolution due to the components of the wave train analyzed, advances in joint inversions are continuing to refine the tomographic images generated with(More)
Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in GRACE but without a discernible coseismic(More)
Finite-fault earthquake source inversions infer the (time-dependent) displacement on the rupture surface from geophysical data. The resulting earthquake source models document the complexity of the rupture process. However, multiple source models for the same earthquake, obtained by different research teams, often exhibit remarkable dissimilarities. To(More)