Earth's free oscillations excited by the 26 December 2004 Sumatra-Andaman earthquake
Park, J.; Song, T.-R.A.; Tromp, J.; Okal, E.A.; Stein, S.; Roult, G.; Clevede, E.; Laske, G.; Kanamori, H.; Davis, P.; Berger, J.; Braitenberg, C.; Van Camp, M.; Lei, X.; Sun, H.; Xu, H.; Rosat, S. (2005). Earth's free oscillations excited by the 26 December 2004 Sumatra-Andaman earthquake. Science (Wash.) 308(5725): 1139-1144. http://dx.doi.org/10.1126/science.1112305 In: Science (Washington). American Association for the Advancement of Science: New York, N.Y. ISSN 0036-8075; e-ISSN 1095-9203, more |  |
| Authors | | Top | - Park, J.
- Song, T.-R.A.
- Tromp, J.
- Okal, E.A.
- Stein, S.
- Roult, G.
| - Clevede, E.
- Laske, G.
- Kanamori, H.
- Davis, P.
- Berger, J.
- Braitenberg, C.
| - Van Camp, M., more
- Lei, X.
- Sun, H.
- Xu, H.
- Rosat, S., more
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| Abstract | 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. |
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