Strong ground motion simulation of the 1999 Chi‐Chi, Taiwan earthquake from a realistic three‐dimensional source and crustal structure

Abstract

[1] We simulate the strong ground motion of 1999 Chi-Chi, Taiwan earthquake (M w = 7.6) by considering a three-dimensional source rupture model in a full waveform three-dimensional wave propagation study. The strong ground motion records during the 1999 Chi-Chi earthquake show various characteristics at different sites in Taiwan. We adopt a three-dimensional source model derived from an inversion study with identical path effects as considered in this three-dimensional forward study. Comparisons between the simulation results and observed waveforms from dense island-wide strong motion stations demonstrate that the fault geometry, lateral velocity variation, and complex source rupture process greatly influence the distribution of strong ground shaking. The simulation has reproduced the heavy damage area that is mainly concentrated in the hanging wall, especially close to the surface break of the Chelungpu fault. The source directivity effect is also reproduced and shows serious shaking along the northward rupture direction. Low-velocity material in the shallow part of the Western Plain is found to generate significantly amplified ground motions. In the Central Range, the shaking is relatively weak owing to the energy radiation characteristics of a low-angle thrust of the Chelungpu faulting system. The wavefield is then amplified by a high-velocity gradient under the Coastal Range. Our simulation results in the frequency range of 0.01-0.5 Hz give good agreement with the extensive strong motion observations of the Chi-Chi earthquake. We find that adequate source representation, good three-dimensional crustal velocity structures, and careful numerical work are necessary to make the ground motion prediction feasible.

Run-Time GPU Computing and Rendering of Earthquake Ground-Motion Data

“…Some features of the Chi-Chi earthquake from the ground acceleration field, ground velocity field, and ground displacement field data, based on [5] and [6] are listed below: (1) The peak ground acceleration (PGA) is generally higher in the northern part of the source region. (2) The shaking motion occurs along the northward rupture direction.…”

Typical landslides and related mechanisms in Ali Mountain highway induced by typhoon Morakot: perspectives from engineering geology

“…It is observed that more buildings are damaged on the hanging wall compared with the buildings on the footwall. The phenomena can be attributed to the hanging wall effect of strong ground motion (Abrahamson and Somerville 1996;Allen et al 1998;Lee et al 2007) and/or the complex surface deformation pattern on the hanging wall (Lee et al 2000). The earthquake-triggered landslides also show significant near fault and hanging wall effects (Sato et al 2007;Yagi et al 2009 Yin et al 2010).…”

“…Relatively speaking, the influence of earthquakes on the slopes along the Ali Mountain Highway has been less severe compared to the heavy rainfall. A total of 24 landslides were triggered by the 1998 Jueili earthquake (977 m 3 ) and the 1999 Chi-Chi earthquake (23634 m 3 ) along the Ali Mountain Highway (Lee et al 2005). However, the strong motion induced by the earthquake had a lasting effect on the stability of the slopes for more than 5 years (Lee et al 2005).…”

The Geophysical Database Management System in Taiwan

“…By inverting the broadband seismic records, the source parameters (e.g., Kao and Jian 1999;Kao et al 2001) and the source rupture process (e.g., Lee et al 2008Lee et al , 2010Huang et al 2011) can be determined. In addition, broadband data also provides a constraint for wave propagation simulation on validating models (e.g., Lee et al 2007). The difference between calculated and observed data can be used to evaluate the seismic site effect.…”