HR: 1330h
AN: U53A-06    [Abstracts]
TI: Low Frequency Data Analysis From the 2004 Great Sumatra Earthquake
AU: * Cao, A
EM: acao@seismo.berkeley.edu
AF: Berkeley Seismological Lab University of California, Berkeley, 215 McCone Hall, Berkeley, CA 94720 United States
AU: Rhie, J
EM: rhie@seismo.berkeley.edu
AF: Berkeley Seismological Lab University of California, Berkeley, 215 McCone Hall, Berkeley, CA 94720 United States
AU: Uhrhammer, R
EM: bob@seismo.berkeley.edu
AF: Berkeley Seismological Lab University of California, Berkeley, 215 McCone Hall, Berkeley, CA 94720 United States
AU: Romanowicz, B
EM: barbara@seismo.berkeley.edu
AF: Berkeley Seismological Lab University of California, Berkeley, 215 McCone Hall, Berkeley, CA 94720 United States
AB: For seismologists, the great Sumatra earthquake of 12/26/04 brought home several striking facts: 1) As the largest earthquake in 40 years, and the first one since the establishment of regional and global networks of digital, high dynamic range, broadband seismic sensors. Data of unprecedented quality have been acquired for this event, in particular at frequencies corresponding to the gravest modes of oscillation of the Earth. It is a unique opportunity to verify fundamental properties of the earth's global structure, previously acquired at great effort through stacking of lesser quality data. 2) The Mw 9.0 event caught seismologists unaware: until now, the sophisticated procedures developed in the last 20 years to model earthquake ruptures have been targeted at the more frequent Mw 7.0-8.0 earthquakes. Consequently, a whole new dimension of the earthquake source problem has suddenly emerged, necessitating the consideration of longer source durations, larger source lengths, more complex source rupture models, all this using a wider bandwidth. We will present preliminary results and inferences from measurements and modeling of splitting and attenuation of low frequency normal modes from the Sumatra earthquake, as well as attempt to address the controversy concerning the mode of strain release in the northern part of the rupture, using data from very long period records.
DE: 7200 SEISMOLOGY
SC: Union [U]
MN: 2005 Joint Assembly