1909 Taipei Earthquake Ground Motion Simulation

Abstract

The 1909 Taipei earthquake (M 7.3) occurred beneath the Taipei metropolitan area (TMA) causing substantial damage according to the historical literature. According to the hypocenter relocation and tectonic implications provided in a previous study, we simulated ground motions within the TMA using a hybrid simulation method involving the spectral-element method (SEM) and the empirical Green's function method (EGFM). We used the SEM for simulating low-frequency components and the EGFM for simulating high-frequency components. These high and low frequency components were subsequently combined. For the EGFM we used the records from a recent M L 4.9 earthquake (11 October 2013, depth = 143.8 km) in the Taipei area as the empirical Green's function. According to the historical literature, the observed PGA (peak ground acceleration) values are 59.2 and 67.0 gal at ancient stations TAP and KEE, with periods of 1.21 and 1.34 s, respectively. By comparing the simulated PGA values at modern stations TAPB and WFSB to the historical documented ones for 12 different models, our result suggests that the 1909 Taipei earthquake was an event with a magnitude of about M w 7.3 and stress drop of approximately 30 bars, or a smaller equivalent magnitude between M w 6.8 -7.3 but with much higher average stress drop of more than 100 bars. For a deep event beneath TMA a larger vertical P-wave motion and longer period shaking wave, as addressed in the historical literature, might be expected with prolonged shaking as found in the simulation. A seismic hazard assessment is necessary for metropolitan Taipei to better understand the long period shaking from deep subduction zone intra plate events.

Synthetic Ground-Motion Simulation Using a Spatial Stochastic Model with Slip Self-Similarity: Toward Near-Source Ground-Motion Validation

“…Deterministic ground-motion prediction, prediction using earthquake scenario simulations, is attracting much research interest. To reliably simulate these scenarios requires comprehensive knowledge of fault models, especially knowledge of the geometry and slip heterogeneity of finite faults (Liao et al 2016;Wen et al 2016). …”

Preface to the Special Issue on “Taiwan Earthquake Model: Seismic Hazard Assessment and Earthquake Scenario”

“…They demonstrated that, despite the complex structure in eastern Taiwan, their hybrid approach successfully replicated the overall characteristics of broadband ground motion for the 2013 Ruisui earthquake. Liao et al (2016) performed a hybrid method comprising both the spectral-element and the empirical Green's function methods to simulate the ground motion of the 1909 Taipei earthquake. Their study indicated that the moment magnitude of the 1909 Taipei earthquake was either 7.3 with a stress drop of 30 bars, or between 6.8 and 7.3, but with a higher stress drop of > 100 bars.…”