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Postseismic response of repeating aftershocks
Author(s) -
Schaff David P.,
Beroza Gregory C.,
Shaw Bruce E.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1998gl900192
Subject(s) - aftershock , creep , geology , viscoelasticity , seismology , slip (aerodynamics) , power law , rheology , logarithm , deformation (meteorology) , fault (geology) , exponential decay , geodesy , physics , thermodynamics , mathematical analysis , statistics , oceanography , mathematics , nuclear physics
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.