Koper, Keith D. and Hutko, Alexander R. and Lay, Thorne and Ammon, Charles J. and Kanamori, Hiroo (2011) Frequency-dependent rupture process of the 2011 M_w 9.0 Tohoku Earthquake: Comparison of short-period P wave backprojection images and broadband seismic rupture models. Earth Planets and Space, 63 (7). pp. 599-602. ISSN 1343-8832 http://resolver.caltech.edu/CaltechAUTHORS:20120105-100359903
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The frequency-dependent rupture process of the 11 March 2011 M_w 9.0 off the Pacific coast of Tohoku Earthquake is examined using backprojection (BP) imaging with teleseismic short-period (~1 s) P waves, and finite faulting models (FFMs) of the seismic moment and slip distributions inverted from broadband (>3 s) teleseismic P waves, Rayleigh waves and regional continuous GPS ground motions. Robust features of the BPs are initial down-dip propagation of the short-period energy source with a slow rupture speed (~1 km/s), followed by faster (2-3 km/s) rupture that progresses southwestward beneath the Honshu coastline. The FFMs indicate initial slow down-dip expansion of the rupture followed by concentrated long-period radiation up-dip of the hypocenter, then southwestward expansion of the rupture. We explore whether these differences correspond to real variations in energy release over the fault plane or represent uncertainties in the respective approaches. Tests of the BP results involve (1) comparisons with backprojection of synthetic P waves generated for the FFMs, and (2) comparisons of backprojection locations for aftershocks with corresponding NEIC and JMA locations. The data indicate that the down-dip environment radiates higher relative levels of short-period radiation than the up-dip regime for this great earthquake, consistent with large-scale segmentation of the frictional properties of the megathrust.
|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 12, 2011; Accepted May 20, 2011; Online published September 27, 2011. This work made use of GMT and SAC software. The IRIS DMS and Orfeus data centers were 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, EAR098660, EAR0951558 and USGS Award Number 05HQGR0174. We thank two anonymous referees for thoughtful comments.|
|Subject Keywords:||Great earthquakes; back-projection; reverse-time imaging; seismic energy|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||06 Jan 2012 16:47|
|Last Modified:||06 Jan 2012 16:47|
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