Earth's free oscillations excited by the 26 December 2004 Sumatra-Andaman earthquake

Jeffrey Park, Teh Ru Alex Song, Jeroen Tromp, Emile Okal, Seth Stein, Genevieve Roult, Eric Clevede, Gabi Laske, Hiroo Kanamori, Peter Davis, Jon Berger, Carla Braitenberg, Michel Van Camp, Xiang'e Lei, Heping Sun, Houze Xu, Severine Rosat

Research output: Contribution to journalReview articlepeer-review

225 Scopus citations


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 × 1022 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.

Original languageEnglish (US)
Pages (from-to)1139-1144
Number of pages6
Issue number5725
StatePublished - May 20 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General


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