Line‐Source Model Based Rapid Inversion for Deriving Large Earthquake Rupture Characteristics Using High‐Rate GNSS Observations

Abstract

When a large earthquake (M w > 6) occurs, rapid generation of ground shaking map is crucial for the identification of serious damage regions, contributing to disaster assessment and emergency response (Wald et al., 1999). In the majority of traditional earthquake early warning (EEW) systems, the ground shaking maps are constructed using empirical ground motion prediction equations (GMPEs) based on a point source model (Allen et al., 2009;Böse et al., 2014). As a result, the predicted ground motion field may have an isotropic shape, which is inconsistent with the actual rupture pattern of large earthquakes (Convertito et al., 2012). Since the rupture lengths of large earthquakes can range from tens to hundreds of kilometers (Wells & Coppersmith, 1994), ignoring the earthquake rupture characteristics (e.g., rupture length, direction, and pattern) may result in an underestimation of ground shaking, especially in the predominant rupture direction (Hoshiba & Iwakiri, 2011;Sagiya et al., 2011). Therefore, the rapid determination of rupture characteristics for large earthquakes can refine the prediction of ground shaking, and bring benefits for the disaster assessment and emergency response (Böse et al., 2021;Kurahashi & Irikura, 2011).Recently, several methods have been developed for estimating earthquake rupture characteristics using seismic networks. Jan et al. ( 2018) presented a near-real-time method for estimating earthquake rupture directivity, but this method can not determine fault rupture length for large earthquakes. A Finite-Fault Rupture Detector (FinDer) algorithm was proposed to swiftly determine line-source models of large earthquakes within a few to several tens of seconds using a dense seismic network (Böse et al., 2012(Böse et al., , 2015(Böse et al., , 2018. However, dense observation networks only exist in a rare number of regions, such as Japan, Taiwan, and the west coast of the United States, limiting the