Viscoelastic Deformation Model
Bridget Smith and David Sandwell
in preparation., 2004
Quick Contents:
Fourier viscoelastic model derivation
Example viscoelastic models (animations)
San Andreas
viscoelastic model
Following
the elastic
halfspace derivation, we
have developed a semianalytic, timedependent
model for 3D displacement and stress caused by a dislocation in an
elastic halfspace over a
viscoelastic halfspace. All solutions have been developed in the
Fourier domain to exploit the
speed of the convolution theorem. In addition, a new analytic solution
has been developed
following the Boussinesq Problem that satisfies the necessary surface
and layer boundary
conditions and also includes the restoring force of gravity.
We use this model to
investigate the viscoelastic behavior of fault deformation for
different
stages of the earthquake cycle. The model consistis of an elastic
lithosphere overlying a
viscoelatic ashenosphere [Savage
and Prescott, 1978] that
is coupled by shear stress across the
elasticviscoelastic interface. Following an earthquake, ductile
regions within the Earth respond to an instntaneous transfer of stress
by solowly relaxing with time and transferring a
shear load back onto the asthenosphere [Thatcher, 1983]. This short period of
timedependent
deformation allows deeply focused stress to relax, ultimately reloading
a locked fault and
initiating the earthquake cycle sequence repeatedly. Elastic plate
thickness, rheological
constraints, and the role of gravity play a key role in 3D velocity
and stress behavior.
Future complex models, constrained
by both geologic and geodetic observations of the San Andreas Fault
System, will be establised in
order to improve our understanding of temporal plateboundary
deformation and stress variations throughout the earthquake cycle.
