Tsunami inundation from heterogeneous earthquake slip distributions: Evaluation of synthetic source models

Abstract

This study investigates whether eight different synthetic finite fault models (SFFM) can simulate stochastic earthquake‐tsunami with similar statistical properties to “real” earthquake‐tsunami events, where the latter are represented using heterogeneous slip distributions from 66 Finite Fault Inversions (FFI) for oceanic subduction interface earthquakes. A new method is derived to estimate SFFM parameters from FFI, and predictive relations between the earthquake moment magnitude and the SFFM corner wave numbers are developed to support model applications. SFFM with more capacity to spatially localize slip are better able to simulate higher slip regions on the FFI, and this strongly influences their associated tsunami inundation, which is computed in two dimensions over idealized topography. The best performing SFFM generates tsunami inundation which envelopes the FFI inundation in 81% of cases using 10 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 localized slip distributions. None of the SFFM showed a tendency to overpredict inundation. 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 nonconservative bias in tsunami hazard assessments. However, the most successful model used here performs quite well, although it may still underestimate inundation more often than an optimal model.

From regional to local SPTHA: efficient computation of probabilistic tsunami inundation maps addressing near-field sources

“…Probabilistic tsunami hazard analysis (PTHA) probably began with the seminal papers of Lin and Tung (1982) and Rikitake and Aida (1988). Uncertainty quantification is one of the main goals of PTHA, and progressively more refined uncertainty treatment was achieved following the 2004 Indian Ocean tsunami (e.g., Geist and Parsons, 2006;Burbidge et al, 2008;González et al, 2009;Horspool et al, 2014;Hoechner et al, 2016;Selva et al, 2016;Davies et al, 2017;Grezio et al, 2017;Power et al, 2017). PTHA is becoming the established good practice for managing risk assessment and risk mitigation measures (Chock et al, 2016;Løvholt et al, 2017).…”

The effect of uncertainty in earthquake fault parameters on the maximum wave height from a tsunami propagation model

“…This work was continued in Geist (2012) who showed that far-field amplitude scaled with scalar seismic moment but with significant uncertainty in the correlation. Other studies, such as Davies et al (2015), McCloskey et al (2007McCloskey et al ( , 2008, Løvholt et al (2012) or Goda et al (2014), have investigated the effect of non-uniform slip on the nearshore maximum tsunami height or on the maximum inundation height. However, these studies have generally focused on one particular location and thus on a limited range of distances and azimuths.…”

New Scaling Relationships of Earthquake Source Parameters for Stochastic Tsunami Simulation

“…For instance, scaling relationships that evaluate the width and length of a fault plane as a function of moment magnitude can be used to determine the geometry of an earthquake rupture for a given scenario. Moreover, randomness and heterogeneity of spatial earthquake slip distribution, which have major influence on tsunami hazard assessment [Geist, 2002;Løvholt et al, 2012;Goda et al, 2014Goda et al, , 2015Davies et al, 2015], can be characterized by wavenumber spectra [Mai and Beroza, 2002;Lavallée et al, 2006]. Possible realizations of constrained random slip fields are normally generated using spectral synthesis methods and integrated into probabilistic tsunami hazard and risk assessment [Goda et al, 2014Fukutani et al, 2015;Goda and Abilova, 2016].…”