HR: 1340h
AN: T43B-1347    [Abstracts]
TI: Pre-seismic Change of Groundwater Level Prior to the 2000 M_L6.7 Earthquake in Taiwan
AU: * Liu, C
EM: r95224109@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan, 10617,
AU: Chia, Y
EM: ypc@ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan, 10617,
AU: Ho, W
AF: Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan, 10617,
AU: Lin, Y
AF: Central Geological Survey, No.2, Lane 109, Huasin St., Jhonghe, Taiwan, 235,
AU: Kuan, Y
AF: Water Resources Agency, 9-12F 41-3 Sec.3 Hsin-yi Rd., Taipei, Taiwan, 10651,
AB: Groundwater-level changes may reflect co-seismic tectonic stress redistribution and crustal strain. Earthquake- related groundwater level changes have been monitored by more than 600 wells in Taiwan. The Pingding (PD) well is one of the monitoring wells, located at the northern tip of the Douliu Hill, and was installed in an aquifer consisting of semi-consolidated deposits. The site is right on the axis of an anticline extending from north to south. The 206 m deep well has been monitored since 1997, and the water-level is recorded at one hour-interval with a resolution of 1 cm. According to the monitoring data, the well water-level is quite complete, and usually changes very slowly, even during the rainfall. We analyzed the response of water-level in the PD well to earthquakes of magnitude greater than 5.5 in the Richter scale from 1997 to 2005. Co-seismic water-level changes were observed in 19 of 78 earthquakes; about half of the changes are water-level rises. An abnormal water-level change was found approximately one hour immediately before the co-seismic change during the 2000 M_L6.7 earthquake. The phenomena imply that the well water-level in PD not only reflects the change of tectonic stress induced by earthquakes, but also responds to the pre-earthquake crustal deformation.
DE: 1200 GEODESY AND GRAVITY
DE: 7221 Paleoseismology (8036)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8107 Continental neotectonics (8002)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting