This study investigates whether four different Synthetic Finite Fault Models (SFFM) can simulate stochastic earthquake tsunami with similar statistical properties to real earthquake-tsunami events. The latter are represented using heterogenous slip distributions from Finite Fault Inversions (FFI) for oceanic subduction interface earthquakes. To apply the SFFM, regression relations are developed between earthquake moment magnitude and parameters controlling the slip roughness, using a new method to fit SFFM to FFI.
SFFM with more capacity to spatially localize slip are better able to simulate higher-slip regions on the FFI, which have the most in
fluence on tsunami inundation in our simulations. The tsunami inundation associated with the FFI and SFFM is computed in two-dimensions over idealised topography.
The best-performing SFFM generates tsunami inundation which envelopes the FFI inundation in 77% of cases using ten synthetic events (close to the ideal value of 82%), while the other SFFM show greater tendencies to underestimate inundation. These differences are related to the capacity of each
SFFM to produce spatially localised slip distributions. The results highlight that SFFM cannot be assumed to reliably quantify uncertainties in the tsunami inundation of real earthquakes, and the use of untested SFFM could create non-conservative bias in tsunami hazard assessments. However the most successful model used here performs quite well, although it probably underestimates inundation for small earthquakes more often than an optimal model.