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A window into the complexity of the dynamic rupture of the 2011 Mw 9 Tohoku-Oki earthquake

Meng, Lingsen and Inbal, Asaf and Ampuero, Jean-Paul (2011) A window into the complexity of the dynamic rupture of the 2011 Mw 9 Tohoku-Oki earthquake. Geophysical Research Letters, 38 (7). Art. No. L00G07. ISSN 0094-8276. doi:10.1029/2011GL048118.

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The 2011 Mw 9 Tohoku-Oki earthquake, recorded by over 1000 near-field stations and multiple large-aperture arrays, is by far the best recorded earthquake in the history of seismology and provides unique opportunities to address fundamental issues in earthquake source dynamics. Here we conduct a high resolution array analysis based on recordings from the USarray and the European network. The mutually consistent results from both arrays reveal rupture complexity with unprecedented resolution, involving phases of diverse rupture speed and intermittent high frequency bursts within slow speed phases, which suggests spatially heterogeneous material properties. The earthquake initially propagates down-dip, with a slow initiation phase followed by sustained propagation at speeds of 3 km/s. The rupture then slows down to 1.5 km/s for 60 seconds. A rich sequence of bursts is generated along the down-dip rim of this slow and roughly circular rupture front. Before the end of the slow phase an extremely fast rupture front detaches at about 5 km/s towards the North. Finally a rupture front propagates towards the south running at about 2.5 km/s for over 100 km. Key features of the rupture process are confirmed by the strong motion data recorded by K-net and KIK-net. The energetic high frequency radiation episodes within a slow rupture phase suggests a patchy image of the brittle-ductile transition zone, composed of discrete brittle asperities within a ductile matrix. The high frequency is generated mainly at the down-dip edge of the principal slip regions constrained by geodesy, suggesting a variation along dip of the mechanical properties of the mega thrust fault or their spatial heterogeneity that affects rise time.

Item Type:Article
Related URLs:
URLURL TypeDescription
Meng, Lingsen0000-0003-2428-0548
Inbal, Asaf0000-0001-8848-7279
Ampuero, Jean-Paul0000-0002-4827-7987
Additional Information:© 2011 American Geophysical Union. Received 16 May 2011; accepted 20 July 2011; published 24 August 2011. This research was supported by NSF grant EAR-1015704, by the Gordon and Betty Moore Foundation, and by the Southern California Earthquake Center, which is funded by NSF cooperative agreement EAR-0106924 and USGS cooperative agreement 02HQAG0008. This paper is Caltech Tectonics Observatory contribution #173 and Caltech Seismolab contribution SCEC #1501. The Editor thanks Jon Fletcher and an anonymous reviewer for their assistance in evaluating this paper.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Southern California Earthquake Center (SCEC)UNSPECIFIED
Subject Keywords:back-projection; seismic array; 2011 Tohoku-Oki earthquake
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory173
Southern California Earthquake Center (SCEC)1501
Issue or Number:7
Record Number:CaltechAUTHORS:20111005-101407350
Persistent URL:
Official Citation:Meng, L., A. Inbal, and J.-P. Ampuero (2011), A window into the complexity of the dynamic rupture of the 2011 Mw 9 Tohoku-Oki earthquake, Geophys. Res. Lett., 38, L00G07, doi:10.1029/2011GL048118.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:26595
Deposited On:05 Oct 2011 20:08
Last Modified:09 Nov 2021 16:42

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