Area Balancing Method as a Useful Tool to Estimate the Depth of the Chi-Chi Earthquake Rupture at the Fengyuan Well

Yuan-Hsi Lee, Shih-Ting Lu, Tung-Sheng Shih
2006 Terrestrial, Atmospheric and Oceanic Sciences  
The 1999 Chi-Chi earthquake, M w = 7.6, was associated with a near 100-km-long surface rupture along which the horizontal slip and vertical displacement reached to 9 m and 4 m, respectively, according to coseismic GPS slip vectors. After the Chi-Chi earthquake, drilling projects were conducted to clarify the characteristics of the earthquake rupture in depth. At the Fengyuan site, inclined-well drilling was performed at an angle of 50 degrees westward to a drilling depth of 455.3 m in the
more » ... rn segment of the Chi-Chi earthquake rupture. Two possible earthquake rupture zones were observed at drilling depths of 225 m and 330 m according to the core structures and seismic profiling. We apply an area balancing method to determine the depth of the earthquake rupture in the cores; and we suggest that the 330-m drilling depth is the most likely candidate for the earthquake rupture. (Key words: Chelungpu fault, Area balancing method, Chi-Chi earthquake, Fengyuan well)
doi:10.3319/tao.2006.17.3.489(t) fatcat:xozwul6lbjfyja6zgesgaicsoa