Long-period ocean sound waves constrain shallow slip and tsunamis in megathrust ruptures
Kozdon, Jeremy E.
Dunham, Eric M.
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Great earthquakes along subduction-zone plate boundaries, like the magnitude 9.0 Tohoku-Oki, Japan, event, deform the seafloor to generate massive tsunamis. Tsunami wave heights near shore are greatest when excitation occurs far offshore near the trench, where water depths are greatest and fault slip is shallow. Unfortunately the rupture process there is poorly constrained with land-based geodetic and even seafloor deformation measurements. Here we demonstrate, through dynamic rupture simulations of the Tohoku event, that long-period sound waves in the ocean, observable with ocean-bottom pressure sensors and/or seismometers, can resolve the shallow rupture process and tsunami excitation near the trench. These waves could potentially be used to improve local tsunami early warning systems.