[SIO GP Seminars] Reminder: Mike Oskin, 2 PM, Munk

[Daniel Brothers]

Please join us for a special GP seminar this Thursday.



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Thursday, March 15, 2:15 PM
(refreshments served at 2:00 PM)
Munk Conference Room

Mike Oskin
University of North Carolina at Chapel Hill

"Fault system behavior of the Eastern California shear zone: Unsteady  
loading rates and clustered earthquake activity"

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Abstract:
Clustering of major earthquakes over periods of years to decades is
observed historically and in paleoseismic records. Seismic hazard
forecasts may be improved by identifying a cluster in-progress and
its relationship to fault loading processes. I present new long-term
fault slip-rates from the Eastern California shear zone (ECSZ), where
both paleoseismic and historic earthquake clusters are recognized, to
test if the interseismic loading rate is transiently elevated during
the present cluster of activity.  The sum of six fault slip rates
that average a few to several tens of earthquakes is 5.9±1.4 mm/yr.
This long-term rate is only half the present-day loading rate of 12±2
mm/yr across the 60 km-wide shear-zone. This discrepancy began prior
to the 1992 Mw 7.3 Landers earthquake, and its magnitude precludes
residual post-seismic deformation following other large historic
earthquakes in southern California. These observations support that
significantly elevated regional strain accumulation rate may be
characteristic of clustered earthquake activity, and that
interseismic loading may oscillate between different fault sets
within a hierarchal fault system.

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