Postseismic response of repeating aftershocks

The recurrence intervals of repeating earthquakes on the San Andreas Fault in the Loma Prieta aftershock zone follow the characteristic 1/t decay of Omori's law. A model in which these earthquakes occur on isolated patches of the fault that fail in stick‐slip with creep around them can explain...

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Bibliographic Details
Published in:Geophysical research letters 1998-12, Vol.25 (24), p.4549-4552
Main Authors: Schaff, David P., Beroza, Gregory C., Shaw, Bruce E.
Format: Article
Language:English
Subjects:
Earth sciences
Earth, ocean, space
Earthquakes, seismology
Exact sciences and technology
Internal geophysics
Marine
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Summary:The recurrence intervals of repeating earthquakes on the San Andreas Fault in the Loma Prieta aftershock zone follow the characteristic 1/t decay of Omori's law. A model in which these earthquakes occur on isolated patches of the fault that fail in stick‐slip with creep around them can explain this observation. In this model the recurrence interval is inversely proportional to the loading rate due to creep. Logarithmic velocity strengthening friction predicts 1/t decay in creep rate following the mainshock. The time dependence of recurrence is inconsistent with a simple viscous constitutive relationship, which predicts an exponential decay of loading rate. Thus, our observations imply postseismic slip at seismogenic depth under a power law rheology. The time dependence of postseismic deformation measured geodetically may be diagnostic of whether postseismic deformation is caused by creep or possible viscoelastic deformation at greater depths.
ISSN:0094-8276
1944-8007
DOI:10.1029/1998GL900192