|
|
||||||||
1 Department of Geosciences
National
Taiwan University
Taipei 106, Taiwan, Republic of China
(W.-S.C.,
C.-C.C., Y.-C.Y., L.-S.L., K.-J.L., H.-C.Y)
2 Central Geological Survey
Taipei
235, Taiwan, Republic of China
(H.-C.C., C.-W.L., W.-H.L., T.-S.S.,
S.-T.L.)
3 Yokohama National University
79-1
Tokiwadai, Hodogaya-ku
Yokohama 240-8501, Japan
(Y.O.)
The geomorphic expression of the frontal Western Foothills in central Taiwan is usually defined by a late Holocene scarp that ranges from tens to hundreds of meters in height. This scarp is the product of displacement on a near-surface 20 30° east-dipping thrust fault, the Chelungpu fault, which ruptured during the Chichi earthquake. The large scarp height may correspond directly to the accumulation of successive surface ruptures. The Chushan site is located on the southern part of this fault where the Chichi earthquake produced a scarp with a 1.7-m vertical offset for the total vertical separation. Based on core-boring estimates, the vertical displacement on both sides is 7 m along a 24° east-dipping thrust fault. The results from our paleoseismic analysis indicate that five large paleoearthquake events have caused the large offsets during the past 2 ka. The radiocarbon age constraints of the paleoearthquakes suggest a clustering of 540790 cal yr B.P. (E2), 710950 cal yr B.P. (E3), 13801700 cal yr B.P. (E4), 17101930 cal yr B.P. (E5), and the 1999 Chichi earthquake. Events E3 and E4 have not been reported in previous studies and we did not observe event E1 (300430 cal yr B.P.) at the site. Based on displacement and fault segmentation from the geologic features, we argue that the two new events may have occurred along the northern part of the Chelungpu fault. The vertical slip rate is estimated to be at least 3.9 ± 0.2 mm/yr over the past 2 ka, which is similar to the long-term estimation through a calculation of late Pleistocene-Holocene terrace elevations on the hanging wall.
This article has been cited by other articles:
![]() |
Ch. Hollenstein, M. D. Muller, A. Geiger, and H.-G. Kahle GPS-Derived Coseismic Displacements Associated with the 2001 Skyros and 2003 Lefkada Earthquakes in Greece Bulletin of the Seismological Society of America, February 1, 2008; 98(1): 149 - 161. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |