Determination of Megathrust Rupture Processes Using 3D Green Functions for Tsunami Early Warning

Abstract:

In order to mitigate disasters from devastating tsunamis caused by large earthquakes occurring in subduction zones, it is necessary to have early warning systems utilizing information from fast determination of rupture processes of the megathrust earthquakes. In this study, we develop a new method for fast and accurate estimation of megathrust rupture processes in the subduction zones, applicable right after occurrence of the earthquakes with large magnitudes, using broadband full waveforms of real-time recording from global seismic network. Most of the tsunami-generating large earthquakes occur on the megathrust faults of subduction regions, locations of which are already known. Therefore, using the most recent numerical models describing the geometries of the plate interfaces in the global subduction zones and the locations of broadband seismic stations in global database, it is possible to calculate Green functions in 3D global earth model well before the occurrence of the earthquake. This will enable the fast calculation of slip models promptly after the earthquake using least square inversion. The resulting slip model can be applied to tsunami model, enabling the fast and accurate prediction of tsunami waves. The applicability of this method is tested with major megathrust earthquakes such as 2011 Tohoku-oki and 2010 Chile earthquake.