HR: 0800h
AN: S31A-0207    [Abstracts]
TI: Relations between rupture velocity changes, seismic radiation, and fault geometry during the Kokoxili earthquake (Tibet, 2001/11/14)
AU: * Vallee, M
EM: vallee@geoazur.unice.fr
AF: Géosciences Azur, IRD, 250, avenue Albert Einstein, Valbonne, 06560, France
AU: Landes, M
EM: landes@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, CNRS, 4, place Jussieu, Paris, 75252, France
AU: Shapiro, N M
EM: nshapiro@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, CNRS, 4, place Jussieu, Paris, 75252, France
AU: Klinger, Y
EM: klinger@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, CNRS, 4, place Jussieu, Paris, 75252, France
AB: Determining how rupture velocity varies during an earthquake provides decisive information on the nature of the rupture process and the associated seismic radiation. We present here an innovative analysis of the 400-km- long Kokoxili earthquake (Tibet, 14 November 2001) using the HIMNT broadband stations located in Nepal as a dense seismic array. This approach reveals that the speed of the propagating rupture tip reached extremely high values, very close to the velocity of seismic compressional waves, over a long fault segment. Although theoretically known since the 1970"s, direct evidences for the existence of this regime had not been provided up to now. We show that the acceleration or deceleration locations related to the transition between low and high velocity regimes are not randomly located but correlate very well with fault geometrical complexities. These transitions are shown to generate strong high frequency radiations and are therefore a very serious candidate to explain the origin of the damaging waves induced by earthquakes.
DE: 7209 Earthquake dynamics (1242)
DE: 7215 Earthquake source observations (1240)
DE: 7255 Surface waves and free oscillations
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Seismology [S]
MN: 2007 Fall Meeting