May
2005
BAGS Meeting:
Topic:
Acoustic Emission Precursors of Large California Earthquakes
Valeri Korneev
Lawrence
Berkeley Laboratory
Thursday, May 26, 2005
Please join us
for lunch in the ChevronTexaco cafeteria. Remember
to request a visitors badge!
Abstract:
Two most recent
large M6.0 2004 Parkfield and M7.0 1998 Loma Prieta earthquakes in San
Andreas Fault (SAF) at California revealed striking similarity in
pre-acoustic emission (AE) behavior which gave distinctive peaks
several months before the events. Similar effects can be observed for
M6 San Simeon 2003, and M4 1993 Parkfiled sequence events. The stress
releasing seismic activity of creeping sections of SAF and main
aftershock seismicity was excluded from the analysis, since they
statistically overwhelm stress build up signatures in the intact
out-of-fault rocks. The subsequent decrease of AE is attributed to rock
softening process which is known from laboratory experiments.
Distinctive zones of low seismic activity surrounding the epicentral
regions in pre-event period are evident for both events. Both AE
boosts and low seismicity epicentral zones can be regarded as promising
precursory phenomena.
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