Viscoelastic Movies
Bridget Smith and David Sandwell
in preparation, 2004
Here we present a 3-D simulation of the earthquake cycle that includes multiple fault elements and explores postseismic deformation for intermediate time scales following an earthquake. The basic model consists of a fault system of three independent segments, A, B, and C, that are imbedded in a 50 km thick elastic plate that is loaded by 40 mm/yr of relative plate motion. Between earthquakes, the middle fault segment, B, is locked from the surface to a depth of 25 km, below which deep, secular slip occurs. The two adjacent fault segments, A and C, are allowed to slip completely to the surface with no locking, simulating uniform fault creep.

In this model, we assume that the fault system is a mature one (geologically evolved), where t = 0 years represents the time of model initiation assuming a full secular plate step is already in place. This model spans 300+ years, where the first 100 years include secular tectonic loading and 4 m of slip will accumulate on the locked segment. At t = 100 years, we simulate an earthquake by initiating coseismic shallow slip (depths < 25 km) on segment B. Following this event, postseismic deformation due to viscoelastic relaxation will occur. We capture single-year snapshots at 5-year increments for both 3-D velocity and Coulomb stress. Alternative velocity models for H= 25km and 100km (d=25km) are also shown below. Coulomb stress models show the postseismic stress response both with and without secular accumulation following the event.

3D velocity: 25km plate 3D velocity: 50km plate (above) 3D velocity: 100km plate
Coulomb stress: no secular Coulomb stress: with secular

Elastic model            
Viscoelastic model