9:00 AM - 9:15 AM
[SSS06-01] Dynamic rupture modeling of near-fault co-seismic displacements during the 2022 Taitung earthquake – what can we constrain using near-fault data?
Keywords:Earthquake source physics, Strong ground motion, Fault friction
Fault friction controls the dynamics of earthquake rupture, yet it is difficult to measure directly in the field. In particular, a slip-weakening distance (Dc) is a key parameter that can be estimated in rare cases when instrumental recordings are made very close to the fault. The 2022 Mw 7.0 Taitung (Taiwan) earthquake occurred in the area of dense instrumentation, with 17 strong-motion stations and 14 high-rate (1 Hz) GNSS receivers surrounding the source area. In particular, 5 strong-motion stations and 6 GNSS receivers are located within the near-fault region (<5 km), and 3 strong-motion sensors are located less than 1 km from the fault rupture. Using strong-motion station F073 located ~200 m from the surface rupture of the main asperity, we estimate Dc in the shallow (<2 km) portion of the fault to be 0.8 m +/- 0.2 m. We also analyze particle motion time histories in a novel way for all the near-fault locations. In addition, we develop dynamic rupture models of the 2022 Taitung earthquake to reproduce the characteristics of near-fault records and infer the fault friction parameters. We find that a model that produces abrupt changes in the rake angle with depth can explain the characteristics of static and dynamic displacements at near-fault sensors on both sides of the fault. Our results also suggest that Dc of 0.7 m in the shallow (<2 km) portion of the fault assumed in our preferred model is consistent with Dc = 0.8 m +/- 0.2 m estimated from the near-fault records. These results suggest that dense near-fault records combined with dynamic rupture simulations can be used to constrain the fault friction parameters.