An Investigation on Multi-Buoy Inversion Method for Tsunami Warning System in South China Sea

Abstract

The key technologies for the development of tsunami warning system include the establishment of tsunami database and inversion method for evaluating source parameters of earthquake by monitored wave data. A tsunami model based on the shallow water equations is adopted to simulate the 2011 Tohoku tsunami to validate the numerical model of generation and propagation of tsunami. The numerical results match well with measured data by DART buoys in terms of the wave height and the arrival time of the tsunami. For the potential earthquake source in the Manila Trench, the numerical model is used to compute the elementary wave fields triggered by unit sources of potential tsunami source with unit slip. Using the tsunami database derived by the elementary wave fields, an inversion method for plate slip based on multi-buoy measurements is applied to compute the time series of surface elevation at the given locations around the coasts in the South China Sea region. Through numerical simulations and multi-buoy inversion computation, the inversed time series of wave profile induced by earthquakes with the magnitudes Mw= 8.0, 8.5, 8.8, 9.35 are obtained. The comparisons of the inversion results and direct simulation data show good agreement. It turns out that, the multi-buoy inversion method works well and, according to the numerical results, deploying one or two buoys along the west side of the Manila Trench is necessary to provide tsunami warning information for the west coasts in the South China Sea. It is suggested that we should deploy one buoy between the south part of Taiwan and the north end of the Manila Trench subduction zone so that we could obtain a good predicted wave height at the south part of Taiwan by the multi-buoy inversion method.