The 1999 Earthquake Fault and Its Repeated Occurrence at the Earthquake Museum, Central Part of Chelungpu Fault, Taiwan

Abstract

This paper reports on the trench log data covering the Chelungpu Fault preserved at the National Science Museum and 10 bore hole data across the fault. Trench log indicates the vertical offset of the 1999 displacement of terrace deposits is ca. 1.5 m and the presence of four branch faults cutting terrace deposits within 1.8 m width zone. Estimated height difference of bedrock surface based on bore hole data is more than 4.2 - 5.8 m, larger than the offset by the 1999 earthquake. These facts imply that at least one earthquake event occurred at this site before the 1999 earthquake. We also estimate the fault plane dips eastward at about 30 degrees based on the location and stratigraphy of one bore hole which penetrates the terrace gravel on the hanging wall through the bedrock.

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