Publication Date:
2003
Description:
We analyze evolving stress and seismicity generated by three realizations of
a discrete model of a strike-slip fault in a 3D elastic half-space using five functions
of stress and five functions of seismicity. The first model (F) has realistic dynamic
weakening (static minus dynamic frictions), the second (FC) has zero critical dynamic
weakening, and the third (SYS) is constrained to produce only system-size events. The
results for model F show cyclical development, saturation, and destruction of
fluctuations and long range correlations on the fault, punctuated by the system-size
events. The development stage involves evolution of stress and seismicity to
distributions having broad ranges of scales, evolution of response functions toward
scale-invariant behavior, increasing seismicity rate and event sizes, and increasing
hypocenter diffusion. Most functions reach asymptotically stable values around 2/3 of
the cycle and then fluctuate until one event cascades to become the next large
earthquake. In model FC the above evolution is replaced by scale-invariant statistical
fluctuations, while in model SYS the signals show simple cyclic behavior. The results
suggest that large earthquake cycles on heterogeneous faults with realistic positive
dynamic weakening are associated with intermittent criticality, produced by spontaneous
evolution of stress heterogeneities toward a critical level of disorder having a broad
range of scales. The stress evolution and development of large earthquake cycles may be
tracked with seismicity functions.
Keywords:
Recurrence of earthquakes
;
Chaotic behaviour
;
SOC
;
Inhomogeneity
;
Fault zone
;
Stress
;
Seismicity
;
3220
;
Mathematical
;
Geophysics:
;
Nonlinear
;
dynamics
;
7209
;
Seismology:
;
Earthquake
;
dynamics
;
and
;
mechanics
;
7223
;
Seismic
;
hazard
;
assessment
;
and
;
prediction
;
7260
;
Theory
;
and
;
modeling
;
8164
;
Tectonophysics:
;
Stresses--crust
;
and
;
lithosphere
;
JGR
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