Revealing Surface Deformation of the 1999 Chi-Chi Earthquake Using High-Density Cadastral Surveying Points in the Shihkang Area,Central Taiwan

• Main Authors: Yu-ching Chen, 陳玉菁
• Other Authors: Yuan-Hsi Lee
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/50041249531784562288

碩士 === 國立中正大學 === 地震研究所暨應用地球物理研究所 === 96 === The 1999 Chi-Chi, Taiwan, earthquake (Mw 7.6) was the largest earthquake to strike Taiwan in the twentieth century. In the northern ending of the Chi-Chi earthquake the horizontal displacement reach near 9 m and associated with EW to NE trending pop up structure which is different from the NS trending main thrust. The pop-up structure is comprised of several north and south vergent thrust. In order to reveal how the displacements distribute in this pop-up structure, we use digital cadastral system to calculate coseismic horizontal displacement. The digital cadastral system was original to define the boundary of the land or building. Taiwan government measures the digital cadastral both before and after the Chi-Chi earthquake. The cadastral system can afford the high density control points that reach ca.10000 points/km2 that is larger than the GPS. The accuracy is less than ±11 cm which higher than the spot image that afford us to study the detail surface deformation. According to the cadastral data we found the coseismic horizontal displacement decreases form 9 to 3.5 m and the azimuth of displacements show large variation from 315°~360° in the pop-up structure. The variations of the displacement amount and azimuth result from strain partition of each fault in the pop-up structure.