Rupture Process of the 1999 Chi-Chi , Taiwan,Earthquake from the Inversion of Teleseismic Data

Abstract

We investigated 22 broadband teleseismic records of the 1999 Chi-Chi earthquake to determine its temporal and spatial slip distribution. The results show an anomalous large slip region centered about 40 to 50 km north of the hypocenter at a shallow depth. The largest amount of slip was about 6~10 m. The slip near the vicinity of the hypocenter had a relatively smaller amount of slip. The spatial slip distribution pattern coincides well with the observed strong-motion displacement and surface break. In the largest dislocation region, the slip was dominated by dip-slip. Some strike-slip component in the middle of the fault was found during the rupture. The Southern portion of the fault showed relatively constant rupture velocity with an average slip of about 1 m, whereas the northern portion of the fault showed significant variations in rupture velocity and produced a large amount of slip.

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