Earth's free oscillations excited by the 26 December 2004 Sumatra-Andaman earthquake.
At periods greater than 1000 seconds, Earth's seismic free oscillations have anomalously large amplitude when referenced to the Harvard Centroid Moment Tensor fault mechanism, which is estimated from 300- to 500-second surface waves. By using more realistic rupture models on a steeper fault derived from seismic body and surface waves, we approximated free oscillation amplitudes with a seismic moment (6.5 x 10(22) Newton.meters) that corresponds to a moment magnitude of 9.15. With a rupture duration of 600 seconds, the fault-rupture models represent seismic observations adequately but underpredict geodetic displacements that argue for slow fault motion beneath the Nicobar and Andaman islands.
Park
Jeffrey
J
Department of Geology and Geophysics, Yale University, Post Office Box 208109, New Haven, CT 06520-8109, USA.
Song
Teh-Ru Alex
TR
Tromp
Jeroen
J
Okal
Emile
E
Stein
Seth
S
Roult
Genevieve
G
Clevede
Eric
E
Laske
Gabi
G
Kanamori
Hiroo
H
Davis
Peter
P
Berger
Jon
J
Braitenberg
Carla
C
Van Camp
Michel
M
Lei
Xiang'e
X
Sun
Heping
H
Xu
Houze
H
Rosat
Severine
S