Cryospherically Induced Stress Fluctuations in Tectonically Active Southern Alaska
Abstract
In tectonically active southern Alaska a strong seasonal cycle of snow accumulation and melt is superimposed on a high rate of annual glacier mass wastage. Our earlier empirical evaluation of the influence of short-term cryospheric fluctuations on the background seismic rate between 1988-2006 (Sauber and Ruppert, 2008) suggested that during the warmer than average years between 2002-2006 there was a stronger seasonal dependency in the frequency of small tectonic events in the Icy Bay region relative to cooler years. Here we extend our earlier Malaspina - Bering Glaciers study to include (1) a relocated set of seismic data to evaluate modulation of seismic rate, (2) well-constrained focal mechanisms to estimate stress orientations as a function of time, and (3) predicted 3-dimensional stresses associated with a complex (un)loading history. Broad-scale, GRACE-derived estimates of cryospheric mass change, along with independent snow melt onset/refreeze timing, snow depth and annual glacier wastage estimates from a variety of methods, were used to approximate the magnitude and timing of cryospheric load changes. We used the CIG finite element code PyLith to enable input of this spatially complex surface load and the calculation of stresses throughout the lithosphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.G13B0516S
- Keywords:
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- 1211 Non-tectonic deformation;
- GEODESY AND GRAVITYDE: 1217 Time variable gravity;
- GEODESY AND GRAVITYDE: 1218 Mass balance;
- GEODESY AND GRAVITYDE: 1236 Rheology of the lithosphere and mantle;
- GEODESY AND GRAVITY