Time reversal imaging of the 2015 Illapel tsunami source

Studies of the 2015 Illapel earthquake show large variance in the east‐west location of the principal slip, and it is also controversial if there is significant slip near the trench. In this study, we derive the initial water elevation from tsunami waves based on the time reversal imaging technique. This approach does not make assumptions on the fault geometry required by finite‐fault inversions. We adopt 4 out of total 24 stations based on their azimuthal coverage in the time reversal analysis. Additionally, we introduce a correction that scales the wave amplitude at each station by the epicentral distance to account for the 2‐D spreading effects. The results show a focused region of water elevation with a maximum height of 2.0 m located approximately 30 km from the trench. By comparison to the initial deformation predicted by several finite‐fault models, our results indicate minimum slip distribution near the trench. Key Points We applied the time reversal imaging technique to the 2015 M8.3 Illapel event to image the tsunami source Albeit limited by the azimuth coverage of tsunami stations, we produce a reasonable image of the tsunami source using four stations Results show an initial water elevation profile with maximum height of 2.0 m located 30 km from trench, indicating little near‐trench slip