Lay, Thorne and Kanamori, Hiroo and Ammon, Charles J. and Koper, Keith D. and Hutko, Alexander R. and Ye, Lingling and Yue, Han and Rushing, Teresa M. (2012) Depth-varying rupture properties of subduction zone megathrust faults. Journal of Geophysical Research B, 117 . Art. No. B04311. ISSN 0148-0227 http://resolver.caltech.edu/CaltechAUTHORS:20120523-094106526
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Subduction zone plate boundary megathrust faults accommodate relative plate motions with spatially varying sliding behavior. The 2004 Sumatra-Andaman (M_w 9.2), 2010 Chile (Mw 8.8), and 2011 Tohoku (M_w 9.0) great earthquakes had similar depth variations in seismic wave radiation across their wide rupture zones – coherent teleseismic short-period radiation preferentially emanated from the deeper portion of the megathrusts whereas the largest fault displacements occurred at shallower depths but produced relatively little coherent short-period radiation. We represent these and other depth-varying seismic characteristics with four distinct failure domains extending along the megathrust from the trench to the downdip edge of the seismogenic zone. We designate the portion of the megathrust less than 15 km below the ocean surface as domain A, the region of tsunami earthquakes. From 15 to ∼35 km deep, large earthquake displacements occur over large-scale regions with only modest coherent short-period radiation, in what we designate as domain B. Rupture of smaller isolated megathrust patches dominate in domain C, which extends from ∼35 to 55 km deep. These isolated patches produce bursts of coherent short-period energy both in great ruptures and in smaller, sometimes repeating, moderate-size events. For the 2011 Tohoku earthquake, the sites of coherent teleseismic short-period radiation are close to areas where local strong ground motions originated. Domain D, found at depths of 30–45 km in subduction zones where relatively young oceanic lithosphere is being underthrust with shallow plate dip, is represented by the occurrence of low-frequency earthquakes, seismic tremor, and slow slip events in a transition zone to stable sliding or ductile flow below the seismogenic zone.
|Additional Information:||© 2012 by the American Geophysical Union. Received 3 January 2012; revised 6 March 2012; accepted 10 March 2012; published 21 April 2012. This work made use of GMT and SAC software. Federation of Digital Seismic Networks (FDSN) seismic data were obtained from the Incorporated Research Institutions for Seismology (IRIS) Data Management System (DMS), and the F-net, K-net, Kik-net, and Hi-net data were obtained from National Research Institute for Earth Science and Disaster Prevention (NIED) data centers. We thank the Editor, Associate Editor, and two anonymous reviewers for their helpful comments on the manuscript. This work was supported by NSF grant EAR0635570 and USGS award 05HQGR0174.|
|Subject Keywords:||2004 Sumatra-Andaman; 2010 Chile earthquake; 2011 Tohoku earthquake; asperities; earthquake rupture; megathrusts|
|Official Citation:||Lay, T., H. Kanamori, C. J. Ammon, K. D. Koper, A. R. Hutko, L. Ye, H. Yue, and T. M. Rushing (2012), Depth-varying rupture properties of subduction zone megathrust faults, J. Geophys. Res., 117, B04311, doi:10.1029/2011JB009133|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||23 May 2012 17:00|
|Last Modified:||26 Dec 2012 15:14|
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