活断層研究
Online ISSN : 2186-5337
Print ISSN : 0918-1024
ISSN-L : 0918-1024
短報
台湾,車籠埔断層中部,「921地震教育園区」付近に おける地震断層とその活動の累積性について
太田 陽子松多 信尚
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ジャーナル フリー

2009 年 2009 巻 31 号 p. 33-38

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The Chelungpu Fault, Taiwan, records the surface rupture by the 1999 Chichi earthquake and abundant information has been obtained on paleoseismology on this fault during the last 10 years. This study area, located on the central part of the Chelungpu Fault, is known as one of the type localities of the surface rupture, but no paleoseismological study was carried out. This paper reports the trench log across the Chelungpu Fault preserved at the Earthquake Museum of Taiwan and tries to reconstruct the faulting history at this site based on 10 bore hole data on the location of the museum. Trench log indicates the displacement of terrace deposits and underlying bedrock by the 1999 earthquake. Four subparallel faults are observed within 1.8 m width, corresponding to the location of the surface rupture. Estimated height difference of bedrock surface based on the bedrock height by bore hole data is more than 4.2 m, significantly larger than the offset by the 1999 earthquake (2-2.5 m). This fact implies that at least two earthquake events including the 921 earthquake occurred at this site. We also estimate the fault plane dips eastward at about 30 degree, based on the location and stratigraphy of one bore hole which penetrates to the terrace gravel on the footwall through the bedrock.

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© 2009 日本活断層学会・活断層研究会
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