Rupture process of the 1999 Chi-Chi, Taiwan, earthquake from the inversionof teleseismic data

We investigated 22 broadband teleseismic records of the 1999 Chi-Chi earthq uake to determine its temporal and spatial slip distribution. The results s how 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 simil ar to 10 m, The slip near the vicinity of the hypocenter had a relatively s maller amount of slip. The spatial slip distribution pattern coincides well with the observed strong-motion displacement and surface break. In the lar gest dislocation region, the slip was dominated by dip-slip. Some strike-sl ip component in the middle of the fault was found during the rupture. The S outhern portion of the fault showed relatively constant rupture velocity wi th an average slip of about 1 m, whereas the northern portion of the fault showed significant variations in rupture velocity and produced a large amou nt of slip.