Simultaneous Inversion of Ocean Bottom Pressure and Electromagnetic Tsunami Records for the 2009 Samoa Earthquake

This study presents tsunami inversion analyses that simultaneously use ocean-bottom pressure and ocean-bottom electromagnetic data along with an accurate tsunami propagation model to estimate the earthquake source model for the 2009 Samoa earthquake. This earthquake was a doublet event that occurred along a pair of normal and thrust faults. To the best of our knowledge, this joint inversion of pressure and electromagnetic data is unprecedented. The incorporation of electromagnetic data in the tsunami inversion analysis was relatively simple, and the inclusion of frequency dispersion, self-attraction, and loading effects in the tsunami propagation calculations allowed the use of tsunami waveforms recorded at distant locations, which improved the reliability of the solutions obtained. Our best source model indicated that the east-west extent of the plate-boundary slip area was approximately 50 km, which is narrower than that of a previous fault model, and explained both electromagnetic and pressure data from the 2009 Samoa tsunami.

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