HR: 1340h
AN: G43B-1213    [Abstracts]
TI: Vertical displacement by absolute and relative gravimetry in Central Taiwan: comparison with GPS, leveling and INSAR results
AU: * Hwang, C
EM: cheinway@mail.nctu.edu.tw
AU: Cheng, T
EM: ctcjohnny@hotmail.com
AU: Hung, W
EM: khung@itri.org.tw
AU: Lu, Y
EM: geine.cv94@nctu.edu.tw
AB: Yunlin and Changhua, located in central Taiwan, are two agricultural counties where significant surface subsidence has occurred over the past decade. The major culprit is pumping of ground water. Measures to stop the subsidence have been taken, but the subsidence continues. To detect the extent and magnitude of recent subsidence here, we use a FG5 absolute gravimeter, and GRAVITON-EG and SCINTREX-5 relative gravimeters to determine gravity changes and consequently subsidence rates. The gravimetric results show varying subsidence rates with the maximum reaching 10 cm/year. Hydrological effects introduce uncertainties to the gravimetric results and require dedicated modeling of ground water, soil moisture and other temporal gravity variations. Ocean tide loadings and seismic effects of earthquakes and ocean dynamics also add to the uncertainties. The gravimetric results are compared with the results from GPS, leveling and PSINSAR. Good agreement between these results is found, despite some large, scattering discrepancies.
DE: 1200 GEODESY AND GRAVITY
DE: 1217 Time variable gravity (7223, 7230)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 1294 Instruments and techniques
DE: 1299 General or miscellaneous (1709)
SC: Geodesy [G]
MN: 2007 Fall Meeting