Project Abstract
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Seismic waves generated by upper crustal earthquakes propagate seismically into the lower crust and upper mantle leaving behind a modified quasi-static stress field. These elastically emplaced stresses may be relaxed by anelastic processes that are often parameterized with time-dependent viscoelastic rheologies. As a result of this stress relaxation at depth the state of stress in the upper crust may evolve in the years to decades following large earthquakes (Pollitz et al., 2003; Freed et al., 2007). Based on these ideas, viscoelastic models have been used to calculate contributions to nominally interseismic geodetic velocities. More rarely these viscoelastic models have been applied at longer time scales (Pollitz et al., 2008; Chuang and Johnson, 2011; Hearn et al., 2013) where the signatures of viscoelastic processes are difficult to deconvolve from tectonic motion. However in light of the suggested sensitivity of earthquake initiation on small stress perturbations (e.g., Feltzer and Brodsky, 2006) the estimation and modeling of the time evolution of these stresses may play an important role in explain delayed earthquake triggering and solid-earth teleconnections. Here we propose to consider this problem at a basic level that elucidates the basic behavior of long-term viscoelastic stress transfer using a novel fault system geometry, periodic and a periodic earthquake sequences and phenomenologically motivated polyviscous rheologies. |
