MLBP application: tsunami warning system

The tsunami warning system based on multi-array back projection using local seismic stations

Accurate prediction of arrival time and height of tsunami waves in the near-field usually requires fast estimation of rupture area. The deployment of dense strong motion stations and recent development in seismic array processing enables rapid tsunami prediction and early warning based on the back-projection (BP) approach, which is useful for near-field tsunamis predictions. The rupture region of the tsunami source is estimated by back-tracing the S-waves recorded by seismometers at local and regional distances. In this work, we develop a multi-array back-projection method using local seismic network (epicentral distance between 0.7 and 3.5 degree). The local BPs (back-azimuth) using individual arrays are first calculated, and then merged into a single image of the rupture process. This multi-array approach circumvents the issue of artifact in single-array BP caused by the overlapping of multiple phases  and coda waves. We apply the multi-array-based tsunami warning approach in a simulated real-time environment to the 2003 Mw 8.0 Tokachi-Oki event and the 2011 Mw 9.0 Tohoku event. The results show that the rupture zone are well resolved and are comparable with principle slip area inferred from tsunami observations. The errors of the amplitudes and arrival times of the predicted tsunami waves are -3.96 to 3.35 m and -8.22 to 16.8.