Publication Date:
2017-04-04
Description:
We have simulated several scenarios of dynamic rupture propagation for the 1994
Northridge, California, earthquake, using a three-dimensional finite-difference method. The simulations
use a rate- and slip-weakening friction law, starting from a range of initial conditions of stress and
frictional parameters. A critical balance between initial conditions and friction parameters must be met
in order to obtain a moment as well as a final slip distribution in agreement with kinematic slip inversion
results. We find that the rupture process is strongly controlled by the average stress and connectivity of
high-stress patches on the fault. In particular, a strong connectivity of the high-stress patches is required
in order to promote the rupture propagation from the initial nucleation to the remaining part of the
fault. Moreover, we find that a small amount of rate-weakening is needed in order to obtain a level of
inhomogeneity in the final slip, similar to that obtained in the kinematic inversion results. However,
when the amount of rate-weakening is increased, the overall moment drops dramatically unless the
average prestress is raised to unrealistic levels. A velocity-weakening parameter on the order of 10 cm
per second is found to be adequate for an average prestress of about a hundred bars. The presence of
the free surface and of the uppermost low-impedance layers in the model are found to have negligible
influence on the rupture dynamics itself, because the top of the fault is at a depth of several kilometers.
The 0.1–0.5 Hz radiated waves from the dynamic simulation provides a good fit to strong motion data
at sites NWH and SSA. Underprediction of the recorded peak amplitude at JFP is likely due to omission
of near-surface low velocity and 3-D basin effects in the simulations.
Description:
Published
Description:
2029-2046
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
reserved
Keywords:
stress drop
;
slip pulses
;
04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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