Effects of dispersion in tsunami Green's functions and implications for joint inversion with seismic and geodetic data: a case study of the 2010 Mentawai M_W 7.8 earthquake

摘要

Tsunami observations play an important role in resolving offshore earthquake slip distributions. Nondispersive shallow-water models are often used with a static initial sea surface pulse derived from seafloor deformation in computation of tsunami Green's functions. We compare this conventional approach with more advanced techniques based on a dispersive model with a static initial sea surface pulse and with the surface waves generated from kinematic seafloor deformation. These three sets of tsunami Green's functions are implemented in finite-fault inversions with and without seismic and geodetic data for the 2010 Mentawai M_w 7.8 tsunami earthquake. Seafloor excitation and wave dispersion produce more spread-out waveforms in the Green's functions leading to larger slip with more compact distribution through the inversions. The fit to the recorded tsunami and the deduced seismic moment, which reflects the displaced water volume, are relatively insensitive to the approach used for computing Green's functions.