Ground‐Motion Prediction Equations for Subduction Slab Earthquakes in Japan Using Site Class and Simple Geometric Attenuation Functions

A horizontal ground-motion model for crustal and subduction earthquakes in Taiwan

“…Therefore, the values are considered separately to distinguish the difference between them. According to the event-term analysis results, the magnitude scaling for subduction interface and intraslab sources are marginally different, which is similar to a previous finding (Zhao et al, 2016a, 2016b). However, due to the limited magnitude range of subduction interface events in Taiwan, we still assume the same magnitude scaling for subduction interface and intraslab sources, as in some other previous studies (Abrahamson et al, 2016; Lin and Lee, 2008), to derive a stable analysis result for subduction interface sources.…”

“…The distances of the used ground-motion records are mostly larger than 40 km. In the studies of Zhao et al (2016a, 2016b), the suggested magnitude breaks for subduction interface and subduction intraslab sources are also Mw = 7.1. Thus, we use their analysis results to determine the magnitude scaling for subduction earthquakes in Taiwan with Mw > Mc and Rrup > 40 km.…”

“…In this study, M c is set as 7.1, which is the maximum magnitude observed in past subduction earthquakes in Taiwan. The magnitude scaling of the subduction interface and intraslab sources obtained using the ground-motion records of large-magnitude subduction earthquakes in Japan (Zhao et al, 2016a, 2016b) is used to determine the magnitude scaling of subduction earthquakes with Mw > 7.1 for predicting the ground-motion intensity of large-magnitude subduction earthquakes in Taiwan. The magnitude scaling is determined using 1,222 ground-motion records from 13 subduction interface earthquakes with Mw > 7.1, including the mainshocks and aftershocks of the Tohoku earthquake, and 539 ground-motion records from seven subduction intraslab earthquakes with Mw > 7.1.…”

“…According to the analysis result of large-magnitude subduction earthquakes in Japan, the geometric attenuation rate for subduction earthquakes with Mw > 7.1, which is equal to that for a subduction earthquake with Mw = 7.1, is assumed to remain constant (Zhao et al, 2016a, 2016b). This assumption is based on the observation of the ground-motion records and finite-fault models of large-magnitude subduction earthquakes with Mw > 7.1 in Japan, where several rupture planes with limited rupture area exist, and only a part of the rupture planes dominates the ground-motion intensity.…”

“…This situation is similar to that encountered in other studies that have attempted to develop ground-motion models for other regions worldwide. For example, ground-motion records with Mw > 7.1 for crustal sources in Europe and the Middle East are insufficient (Akkar et al, 2014); no ground-motion records with Mw > 7.3 for crustal sources are available in California (Abrahamson et al, 2014); and ground-motion records with Mw > 7.1 for crustal sources and Mw > 7.5 for subduction sources in Japan are insufficient (Zhao et al, 2016a, 2016b, 2016c). Model coefficients that control magnitude scaling and distance scaling for scenarios with no or insufficient data cannot be derived or well constrained from regression analysis when developing the ground-motion model.…”