HR: 0800h
AN: T11D-1303    [Abstracts]
TI: Paleoseismology of the 1999 Chichi earthquake rupture, central Taiwan
AU: * Chen, W
EM: wenshan@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No.1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan
AU: Lee, K
EM: oldr123@yahoo.com.tw
AF: Department of Geosciences, National Taiwan University, No.1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan
AU: Lee, L
EM: contractor@pchome.com.tw
AF: Department of Geosciences, National Taiwan University, No.1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan
AU: Yang, H
EM: wenshan@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No.1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan
AU: Yang, C B
EM: d91224003@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No.1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan
AU: Yen, I
EM: yic1228@ms17.hinet.net
AF: Department of Geosciences, National Taiwan University, No.1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan
AU: Chang, H
EM: chang.huicheng@seed.net.tw
AF: Central Geological Survey, MOEA, Lane 109, Hua-Hsin Street, Chung-Ho, Taipei, 235 Taiwan
AU: Lin, C
EM: lincw@linx.moeacgs.gov.tw
AF: Central Geological Survey, MOEA, Lane 109, Hua-Hsin Street, Chung-Ho, Taipei, 235 Taiwan
AU: Lin, W
EM: chaos@linx.moeacgs.gov.tw
AF: Central Geological Survey, MOEA, Lane 109, Hua-Hsin Street, Chung-Ho, Taipei, 235 Taiwan
AU: Shih, T
EM: looneose@linx.moeacgs.gov.tw
AF: Central Geological Survey, MOEA, Lane 109, Hua-Hsin Street, Chung-Ho, Taipei, 235 Taiwan
AB: We integrate with the occurrence ages from the nine trench sites at the different locations, through the chronological dates are constrained the timing of individual seismic events, even the occurrence ages fall in very wide ranges. The chronological constrains for the paleoseismic events however can infer that the at least seven paleoearthquakes occurred during the past 3.1 ka, i.e. they occurred in 1999 AD, 430-300 Cal BP (365$\pm$65 year BP), 790-680 Cal BP (735$\pm$55 year BP), 920-890 Cal BP (905$\pm$15 year BP), 1380-1700 Cal BP (1540$\pm$160 year BP), 1710-1900 Cal BP (1805$\pm$95 year BP), and 2840-3160 Cal BP (3000$\pm$160 year BP), respectively. However, the paleoseismic events permit to be defined time intervals between the displacement events. Recurrence intervals can be estimated for 365$\pm$65 years, 380$\pm$65 years, 170$\pm$35 years, 635$\pm$88 years, 265$\pm$128 years, and 1195$\pm$128 years, respectively. Accordingly, the recurrence intervals are not very uniform except for the last two recurrence intervals. They are well constrained by chronological dates at least in three trenches which is approximately 370$\pm$70 years since 800 year BP. The recurrence intervals in the past 2 ka have occurred in less than 700 years, indicating the minimum interval of about 200 years. The oldest interval has a longer time span of about 1200 years, which are probably not consecutive. But we do not have direct evidence that the events were lacked or eroded in these investigated trenches. Estimate of the coseismic vertical slip rate per event can be obtained 1-5 mm/year. And the long-term vertical slip rate is about 2.4-4.7 mm/year combined with six trenching data.
DE: 7221 Paleoseismology
DE: 8107 Continental neotectonics
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting