Abstract
We couple short-term (i.e. the co-seismic) and long-term (i.e. the
inter-seismic) phase of an earthquake, in order to investigate how
induced static stress changes during the co-seismic phase of an
earthquake cycle influence the dynamics of strain accumulation during
the inter-seismic phase. We perform dynamic rupture simulations on
complex strike slip faults in 2D, incorporating off-fault plastic
failure and strong dynamic weakening on the fault governed by the slip
weakening law. Our strike slip fault has a self-similar fractal profile
with RMS height taken from observational studies. Our dynamic rupture
simulation results show that the stresses in the region surrounding the
fault are highly complex and heterogeneous. This heterogeneity in
stresses is mainly related to roughness of fault profile and at
distances where fault roughness effects are not dominant, the stresses
are mostly uniform. We extract these complex stresses together with the
plastic deformation from the dynamic model and use them as the input to
run the long-term tectonic model (LTM). This provides us insight into
the dynamics of off-fault plastic deformation in the loading phase of an
earthquake. Our LTM results show that most of the shear zones (i.e. new
features e.g. fractures and faults) develop and grow at oblique angles
to the main fault while considerable amount of damage keeps accumulating
along the immediate sides of the fault profile. The development and
growth of these new features occurs in the locations where geometrical
bends in the fault profile has caused the deformation in the dynamic
phase to be localized. This localized deformation due to fault roughness
acts as a seed for the development of new features. We conclude that the
complex damage pattern in the fault damage zones (observed in
observational studies) is mainly due to the fault surface roughness
effects. During the co-seismic phase, the stresses concentrate near the
fault bends due to rough fault profile. During the inter-seismic phase,
these locations are favored for the development of new features during
the inter-seismic phase the earthquake.