Paleoseismology of the Chihshang Fault
Date Issued
2007
Date
2007
Author(s)
Chu, Yao-Kuo
DOI
zh-TW
Abstract
The Longitudinal Valley is an active plate boundary between the Eurasian and Philippine Sea plates. The Chihshang fault located in the southern part of the Longitudinal Valley is an active thrust fault. During the past 50 years, two large earthquakes of the 1951 Taitung earthquake(Mw 6.3) and the 2003 Chengkung earthquake (Mw 6.8) occurred along the Chihshang fault.
The study is aimed at the paleoseismology of the Chihshang fault for understanding the paleoearthquake events, recurrence time, and long-term slip rate. We selected three trenched sites in the Tapo, Chinyuan, and Waan areas and had five cored boreholes along the fault. Additionally, we also surveyed the river terraces on the hanging wall of the fault.
Based on the trench investigation and well-logging record, it shows that the dip of the Chihshang fault is about 45°. Through the paleoseismology study on the Chinyuan and Waan sites, it can be identified at least 5-10 paleoearthquake events for the past about 800 years, and estimating that the Chihshang fault has produced large earthquake with a recurrence interval of 50-170 years. The long-term slip rate is 26-27.4mm/yr based on the uplifted river terrace on both sides of the fault.
Based on the well-logging data, trench and the topographic investigations, we conjectured that some branch faults lie to the west of the Chihshang fault. That branch faults are located in the northern and southern parts of the study area.
Subjects
池上斷層
古地震
地震週期
長期抬升速率
the Chihshang fault
Paleoseismology
recurrence time
longterm slip rate
Type
thesis
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