Three-Dimensional Viscoelastic Models of the Earthquake Cycle

Phoebe Robinson, Harvard University

Explaining the relaxation of stresses and associated transient deformation following a large earthquake is an important step toward understanding the temporal evolution of deformation and stress transfer throughout the entire earthquake cycle. A few models have been developed to calculate stress relaxation following an earthquake with layered linear viscoelastic models in three dimensions (e.g. Wang et al., 2003; Pollitz, 2001; Fukahata and Matsu’ura, 2006; Barbot, 2012; Chuang and Johnson, 2011). These codes involve thousands of fast Fourier transforms and Green’s function calculations and each has limitations: spherical harmonic basis functions that limit near-fault resolution, a limited number of layers, constant shear modulus with depth, and computational inefficiency. We have developed a semi-analytic three-dimensional code that can incorporate an arbitrary number of layers with Maxwell rheologies based on the algorithms of Fukahata and Matsu’ura (2006). Because the rheology is linear, the problem can be parallelized over time, sources, observation points, and wavenumber. Applications will include examining stress changes through the earthquake cycle and the associated implications for earthquake triggering, particularly along the North Anatolian Fault, a continental strike slip fault that has generated 12 large earthquakes (MW greater than 6.0) since 1939.

Abstract Author(s): Phoebe Robinson DeVries and Brendan J. Meade