Investigating the TCDP Drill Site Using Deep and Shallow Reflection Seismics

The 1999 Chi-Chi earthquake (M w = 7.6), Taiwan, reactivated the 105 km long, NS trending Chelungpu fault causing extraordinary surface ruptures. The distribution of the ruptures was quite heterogeneous with the largest displacement (up to 12 m) occurring across the Tachia River, 50 km north of the epicenter. In this study, several different scaled seismic lines are constrained and used to predict the major regional fault geometry. The 3D northern lateral ramp of the Chelungpu fault is clearly found, which provides a structural framework to explain the en echelon surface ruptures around the Tachia River.