TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 63 (No. 7), pp. 797-801, 2011


The 2011 Mw 9.0 off the Pacific coast of Tohoku Earthquake: Comparison of deep-water tsunami signals with finite-fault rupture model predictions

Thorne Lay1, Yoshiki Yamazaki2, Charles J. Ammon3, Kwok Fai Cheung2, and Hiroo Kanamori4

1University of California Santa Cruz, Santa Cruz, California 95064, USA
2University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA
3The Pennsylvania State University, University Park, Pennsylvania 16802, USA
4California Institute of Technology, Pasadena, California 91125, USA

(Received April 7, 2011; Revised May 20, 2011; Accepted May 22, 2011; Online published September 27, 2011)

Abstract: Finite-source rupture models for the great 11 March 2011 off the Pacific coast of Tohoku (Mw 9.0) Earthquake obtained by inversions of seismic waves and geodetic observations are used to reconstruct deep-water tsunami recordings from DART buoys near Japan. One model is from least-squares inversion of teleseismic P waves, and another from iterative least-squares search-based joint inversion of teleseismic P waves, short-arc Rayleigh wave relative source time functions, and high-rate GPS observations from northern Honshu. These rupture model inversions impose similar kinematic constraints on the rupture growth, and both have concentrations of slip of up to 42 m up-dip from the hypocenter, with substantial slip extending to the trench. Tsunami surface elevations were computed using the model NEOWAVE, which includes a vertical momentum equation and a non-hydrostatic pressure term in the nonlinear shallow-water equations to account for the time-history of seafloor deformation and propagation of weakly dispersive tsunami waves. Kinematic seafloor deformations were computed using the Okada solutions for the rupture models. Good matches to the tsunami arrival times and waveforms are achieved for the DART recordings for models with slip extending all the way to the trench, whereas shifting fault slip toward the coast degrades the predictions.
Key words: Great earthquakes, DART buoys, tsunami, finite-fault models, 2011 Tohoku Earthquake.

Corresponding author E-mail: tlay@ucsc.edu

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