Sources of shaking and flooding during the Tohoku-Oki earthquake: A mixture of rupture styles
2012
Wei, Shengji | Graves, Robert | Helmberger, Don | Avouac, Jean-Philippe | Jiang, Junle
Modeling strong ground motions from great subduction zone earthquakes is one of the great challenges of computational seismology. To separate the rupture characteristics from complexities caused by 3D sub-surface geology requires an extraordinary data set such as provided by the recent Mw9.0 Tohoku-Oki earthquake. Here we combine deterministic inversion and dynamically guided forward simulation methods to model over one thousand high-rate GPS and strong motion observations from 0 to 0.25Hz across the entire Honshu Island. Our results display distinct styles of rupture with a deeper generic interplate event (∼Mw8.5) transitioning to a shallow tsunamigenic earthquake (∼Mw9.0) at about 25km depth in a process driven by a strong dynamic weakening mechanism, possibly thermal pressurization. This source model predicts many important features of the broad set of seismic, geodetic and seafloor observations providing a major advance in our understanding of such great natural hazards.
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