Publikationsdatum:
2005
Beschreibung:
We study models of seismicity rate changes caused by the application of a
static stress perturbation to a population of faults and discuss our results with
respect to the model proposed by Dieterich (1994). These models assume a distribution of
nucleation sites (e.g., faults) obeying rate-state frictional relations that fail at
constant rate under tectonic loading alone, and predicts a positive static stress step
at time t 0 will cause an immediate increased seismicity rate that decays according to
Omori's law. We show one way in which the Dieterich model may be constructed from simple
general ideas, illustrated using numerically computed synthetic seismicity and
mathematical formulation. We show that seismicity rate changes predicted by these models
(1) depend on the particular relationship between the clock-advanced failure and fault
maturity, (2) are largest for the faults closest to failure at t 0, (3) depend strongly
on which state evolution law faults obey, and (4) are insensitive to some types of
population heterogeneity. We also find that if individual faults fail repeatedly and
populations are finite, at timescales much longer than typical aftershock durations,
quiescence follows a seismicity rate increase regardless of the specific frictional
relations. For the examined models the quiescence duration is comparable to the ratio of
stress change to stressing rate delta-tau dot tau, which occurs after a time comparable
to the average recurrence interval of the individual faults in the population and
repeats in the absence of any new load perturbations; this simple model may partly
explain observations of repeated clustering of earthquakes.
Schlagwort(e):
Friction
;
Modelling
;
Seismicity
;
JGR
;
7230
;
Seismology:
;
Seismicity
;
and
;
tectonics
;
7223
;
Earthquake
;
interaction,
;
forecasting,
;
and
;
prediction
;
7299
;
General
;
or
;
miscellaneous
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