Time reverse imaging of tsunami waveforms

Abstract

We consider the application of Time Reverse Imaging (TRI) to tsunami waveform data, in order to recover the initial sea surface displacement associated with the tsunami source. We use as a case study the tsunami triggered by the March 11, 2011, Tohoku-Oki earthquake, for which an unprecedented number of high-quality observations are available. The method represents the tsunami source by dividing the source region into a regular grid of “point” sources. For each of these, a tsunami Green’s function (GF) is computed using a basis function for sea surface displacement whose support is concentrated near the grid point. We apply the TRI method to estimate initial sea surface displacement at each source grid point by convolving GFs with time-reversed observed waveforms recorded near the source region. The result for initial sea surface displacement obtained via TRI agrees well with other models obtained using more traditional inversion methods. We show that the TRI method has potential for application in tsunam...