台灣超導及絕對重力觀測：重力基準、地體動力及環境變遷之應用

Abstract

The superconducting gravity (SG) and absolute gravity (AG) observatory in Hsinchu (identified as HS) joined the Global Geodynamics Project (GGP) since 2006. This study is focused on the analysis of gravity datum, geodynamics and environmental change in Taiwan. Most experiments of SG, AG and global positioning system (GPS) are conducted over Taiwan and at HS. Solid and ocean tide gravity effects are estimated from five years of SG data and are compared with models. The performance of HS SG is assessed by comparison of the gravity spectra at HS and at other SG stations. To compare the spectra of residual gravity is from several continuously recording SG stations. We model the gravity variations of non-tectonic origins due to atmosphere, hydrology, and polar motion. The calibration factor (CF) and drifting rate of T48 are 76.087 ± 0.067 μgal voltage-1 and 1.3 ± 0.1 μgal year-1 (1 μgal = 10-8 ms-2). Based on the GPS measuring results, the horizontal rates of plate motion in southeastern Taiwan are about 7-8 cm year-1. A joint Taiwan-France project, called Absolute Gravity for Taiwanese Orogen (AGTO), was initiated in 2006 to study the orogeny of Taiwan using gravimetry and GPS. AGTO measurements show that the average gravity and GPS vertical rate are -1.39±4.21 μgal year-1 and 0.50±0.94 cm year-1, respectively, leading to an average gravity-height ratio (2.78 μgal cm-1). Large (in absolute magnitude) gravity-atmosphere admittances are found during major typhoons. The direct Newtonian and elastic effects due to the atmospheric effects of Kalmaegi typhoon are modeled using the Green’s function approach. Typhoon Morakot (August 2008) caused large landslides at AG3 and AG6 (two stations of AGTO) that created gravity changes of 53 μgal and 27 μgal, and sediment thickness changes of 2.45m and 1.25m.

The superconducting gravity (SG) and absolute gravity (AG) observatory in Hsinchu (identified as HS) joined the Global Geodynamics Project (GGP) since 2006. This study is focused on the analysis of gravity datum, geodynamics and environmental change in Taiwan. Most experiments of SG, AG and global positioning system (GPS) are conducted over Taiwan and at HS. Solid and ocean tide gravity effects are estimated from five years of SG data and are compared with models. The performance of HS SG is assessed by comparison of the gravity spectra at HS and at other SG stations. To compare the spectra of residual gravity is from several continuously recording SG stations. We model the gravity variations of non-tectonic origins due to atmosphere, hydrology, and polar motion. The calibration factor (CF) and drifting rate of T48 are 76.087 ± 0.067 μgal voltage-1 and 1.3 ± 0.1 μgal year-1 (1 μgal = 10-8 ms-2). Based on the GPS measuring results, the horizontal rates of plate motion in southeastern Taiwan are about 7-8 cm year-1. A joint Taiwan-France project, called Absolute Gravity for Taiwanese Orogen (AGTO), was initiated in 2006 to study the orogeny of Taiwan using gravimetry and GPS. AGTO measurements show that the average gravity and GPS vertical rate are -1.39±4.21 μgal year-1 and 0.50±0.94 cm year-1, respectively, leading to an average gravity-height ratio (2.78 μgal cm-1). Large (in absolute magnitude) gravity-atmosphere admittances are found during major typhoons. The direct Newtonian and elastic effects due to the atmospheric effects of Kalmaegi typhoon are modeled using the Green’s function approach. Typhoon Morakot (August 2008) caused large landslides at AG3 and AG6 (two stations of AGTO) that created gravity changes of 53 μgal and 27 μgal, and sediment thickness changes of 2.45m and 1.25m.