HR: 1340h
AN: S53A-0182 [Abstracts]
TI: Rupture Process of the June 23, 2001 Mw 8.4 Peru Earthquake
AU: * Robinson, D P
EM: davidr@earth.ox.ac.uk
AF: Department of Earth Sciences, Oxford University, Parks Road, Oxford, OX1 3PR
United Kingdom
AU: Das, S
EM: das@earth.ox.ac.uk
AF: Department of Earth Sciences, Oxford University, Parks Road, Oxford, OX1 3PR
United Kingdom
AB:
The 2001, Peru, earthquake, the largest earthquake to have happened
worldwide since 1965,
occured off the coast of southern Peru. The largest previous
reported earthquake (Mw $\sim$8.8) in this region occurred
in 1868.
Of the 996 aftershocks reported by the ISC in the 6 months
following the earthquake, we relocate 551 to within an
uncertainty of 30km
and find that the majority form a rectangular zone of length $\sim$350km,
width $\sim$150km and with a strike of $\sim$310$\deg$.We
recalculate the moment tensor using mantle waves from 86 stations and
257 channels and find a solution close to that reported in the Harvard
catalogue (centroid location 17.20$\deg$S, 72.59$\deg$W,
$M_0 \sim 5.66 \times 10^{21}$ Nm, strike 311$^{\circ}$, dip
12$^{\circ}$, rake 68$^{\circ}$). The aftershock area together with the CMT
solution indicates that rupture occurred on a shallowly-dipping
northwest-southeast trending thrust fault associated with the subduction of
the Nazca plate under South America. The rupture zone is contained entirely
within that of the 1868 earthquake (estimated from intensity data).
Inversion of broad band body wave data
shows that most of
the moment release occured between 30 and 100 seconds after the initiation
of the event, and is located from 100-200km to the southeast of
the epicentre. Very preliminary inversions show that
the majority of slip is primarily confined to the shallower portions
of the
crust, providing an explanation for the formation of the associated tsunami.
Although this earthquake ruptured a large portion of the
plate boundary, there still remains a
significant seismic gap of $\sim$700km to its immediate south, off the coast
of northern Chile.
DE: 7230 Seismicity and seismotectonics
DE: 7260 Theory and modeling
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
SC: Seismology [S]
MN: 2004 AGU Fall Meeting