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Outer trench-slope faulting and the 2011 M_w 9.0 off the Pacific coast of Tohoku Earthquake

Lay, Thorne and Ammon, Charles J. and Kanamori, Hiroo and Kim, Marina J. and Xue, Lian (2011) Outer trench-slope faulting and the 2011 M_w 9.0 off the Pacific coast of Tohoku Earthquake. Earth Planets and Space, 63 (7). pp. 713-718. ISSN 1343-8832.

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The 11 March 2011 off the Pacific coast of Tohoku Earthquake (M_w 9.0) produced megathrust displacements of at least 40 m. The resulting tsunami devastated the Honshu coast southwest of regions struck by earthquake-generated tsunami in 1611, 1896 and 1933. The 1896 Meiji-Sanriku earthquake was also an underthrusting earthquake, but the 1933 Sanriku-oki earthquake was a trench-slope normal faulting event; both generated inundation heights of 10 to 25 m along the coast of Iwate prefecture. Possible occurrence of a great outer trench-slope earthquake seaward of the 2011 Tohoku Earthquake along a southwestward extension of the 1933 fault zone is a concern. The second largest 2011 aftershock, an outer rise M_w 7.7 normal faulting earthquake occurred near the southern end of the 1933 rupture. Additional aftershock activity has been distributed along a trend below the trench and diffusely spread in the outer rise, seaward of the megathrust region where the largest slip occurred. Coulomb stress perturbations of at least 5-10 bars are calculated for outer rise normal fault geometries for mainshock slip models. Whether a future great trench slope event will occur is uncertain, but the potential tsunamigenic hazard can be gauged by the huge inundations accompanying the 1933 rupture.

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URLURL TypeDescription DOIArticle CentralArticle
Lay, Thorne0000-0003-2360-4213
Kanamori, Hiroo0000-0001-8219-9428
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 6, 2011; Accepted May 7, 2011; Online published September 27, 2011. This work made use of GMT, SAC and Coulomb 3 software. The IRIS DMS data center was used to access the seismic data. Continuous GPS data processed with 30 s sampling were provided by the ARIA team at JPL and Caltech. This work was supported by NSF grants EAR0635570, EAR0948660, and USGS Award Number 05HQGR0174. We thank T. Seno and an anonymous reviewer for constructive reviews.
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Subject Keywords:Great normal faults; tsunami; 1933 Sanriku-oki; outer rise earthquakes
Issue or Number:7
Record Number:CaltechAUTHORS:20120105-095914613
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28666
Deposited By: Tony Diaz
Deposited On:06 Jan 2012 16:54
Last Modified:03 Oct 2019 03:34

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