A Preliminary Study on Crustal Deformation in Taoyuan-Hsinchu-Miaoli Area, northwestern Taiwan

Based on geodetic measurements in the duration of 2001-2006, this study presents the crustal deformation in the Taoyuan- Hsinchu- Miaoli area of northwestern Taiwan. The geodetic network of campaign mode GPS and leveling lines were deployed by the Central Geological Survey of Taiwan in 2001. The resulted vectors herein are sourced from 3 to 4 times measurements since the network established. The horizontal velocities in the study area are all pointing towards northwest but the amounts not greater than 20 mm/yr. The rates are rather small relative to the other areas in western Taiwan. The displacement field also shows a sense of clockwise rotation when go northward over the Shuanglianpo fault, while turns toward NE and SE when go southward across the Sanyi fault. The vertical displacements significantly vary place by place and there is no obvious uplift observed in hilly area. It needs further analysis to extract the contribution associated with fault movement. In addition, the area between the Hukou fault and the Tapingti fault has uplifted 12mm in the last 2 years. It may be attributed to the recent growth of Hukou anticline, which is previously thought as an active fault by the independent studies on geomorphology and geology.