Tsunami Source Inversions Using Adjoint-state Methods

Lingsen Meng, Tong Zhou, Xie Yuqing, & Jiayuan Han

Published August 14, 2018, SCEC Contribution #8588, 2018 SCEC Annual Meeting Poster #279

Traditional source inversion using tsunamis waves is based on either the finite-fault slip modeling or the time-reversal imaging. Such inversion methods suffer from the uncertainty of fault parameters or crustal rigidity. Moreover, the heavy computational burden of calculating Green’s functions result in limited spatial resolution and hinders the real-time applicability of the traditional methods to tsunami early warning. In this work, we transplant the state-of-art adjoint-state full-waveform inversion method from exploration seismology to tsunami source imaging. The adjoint-state method solves the initial-water-elevation pattern with less computational cost, which potentially improves the speed of the tsunami early warning and reduces the blind zone. Our new method does not rely on pre-defined fault parameters and is suitable for tsunami-generating earthquakes with unknown fault geometry. This method also efficiently handles dense mesh grid and is capable of resolving small-scale secondary tsunami sources, such as the seafloor landslide or secondary ruptures on splay faults. We valid this approach with synthetic tsunami sources, and apply it to the 2014 Mw 8.1 Iquique tsunami event, and the 2017 Mw 8.1 Oaxaca tsunami event. Our preliminary results show that the adjoint-state method is of high resolution and produces little artifacts, outperforming the traditional tsunami source inversions. Our new adjoint-state tsunami inversion will advance tsunami science and earthquake source dynamics and set the stage to improve real-time applications such as tsunami early warning.

Key Words
Tsunami, Source inversion, adjoint-state

Citation
Meng, L., Zhou, T., Yuqing, X., & Han, J. (2018, 08). Tsunami Source Inversions Using Adjoint-state Methods. Poster Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)