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Published September 27, 2011 | public
Journal Article

A rupture model of the 2011 off the Pacific coast of Tohoku Earthquake

Abstract

The 11 March 2011 Tohoku Earthquake ruptured the interplate boundary off-shore of east Japan, with fault displacements of up to 40 m and a rupture duration of 150-160 s. W-phase inversion indicates a moment of 3.9 × 10^(22) N m (M_w 9.0) and a centroid time of 71 s. We invert teleseismic P waves and broadband Rayleigh wave observations with high-rate GPS recordings from Japan to characterize the rupture. The resulting rupture model begins with a steady increase of moment rate for the first 80 s, and a rupture speed of 1.5 km/s. Then the rupture expands southwestward at a speed of about 2.5 km/s. The model's primary slip is concentrated up-dip from the hypocenter, with significant displacement extending to the trench. The seaward location of large slip is consistent with estimates of the tsunami source area from regional and remote tsunami observations. The region with large slip is approximately 150-km wide by 300-km long, which is relatively compact compared with the 200-km wide, 500-km long aftershock region. The model's initial updip rupture expansion and the location of most slip updip of the hypocenter differs from P-wave array back-projections, which map high-frequency radiation along the downdip of the hypocenter, closer to the coast.

Additional Information

© 2011 The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB. Received April 7, 2011; Revised May 13, 2011; Accepted May 18, 2011; Online published September 27, 2011. Seismic data were distributed by the IRIS Data Center. Preliminary GPS time series provided by the ARIA team at JPL and Caltech. All original GEONET RINEX data provided to Caltech by the Geospatial Information Authority (GSI) of Japan. We also thank Luis Rivera for sharing his normal mode summation software and Gavin Hayes for discussions. This work was supported by NSF grant EAR0635570, AFRL Contract FA8718-09-C-007, and Award Number 05HQGR0174. Comments from J. Loveless, K. Yomogida, and K. Koketsu helped improve this manuscript.

Additional details

Created:
August 22, 2023
Modified:
October 24, 2023