Time Reversal Imaging of the 2015 Illapel Tsunami Source

Finite-fault inversions of the 2015 Illapel earthquake show large variance on the east-west location of the principle slip, and debates exist on if the rupture reaches the trench. In this study, we derive the initial water elevation by applying the time reversal imaging (TRI) technique to tsunami waves, which avoids assumptions of fault orientation setup required by finite-fault inversions. Limited by the bad azimuthal coverage of tsunami stations, 4 out of total 24 stations are adopted in the TRI analysis, and the wave amplitude at each station is scaled by the epicentral distance to eliminate the 2d spreading effects. Results show a focused region of water elevation with maximum height of 2.2 m located approximately 30 km from the trench, which indicates little slip near the trench by comparing the results with published finite-fault models.