SCEC Award Number 14012 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Delayed stress transfer with polyviscous rheologies in evolved three-dimensional fault systems
Name Organization
Brendan Meade Harvard University
Other Participants Phoebe Robinson DeVries
SCEC Priorities 1a, 2a, 1b SCEC Groups SDOT, Geodesy, EFP
Report Due Date 03/15/2015 Date Report Submitted N/A
Project Abstract
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.
Intellectual Merit The intellectual merit of this work is to develop the basic scaling relationships for viscoelastic deformation as a function of viscoelastic structure and rupture “length”. This should provide a set of relationships and figures that allow for very rapid assessment the magnitude of these effects without running a specific model.
Broader Impacts The broader impact of this work is less immediately clear. Honestly this is a theoretical study to quantify the magnitudes of viscoelastic deformation with an idealized fault geometry.
Exemplary Figure Figure 2