We have developed the most precise vertical displacement rate field of Taiwan Island to date from four sets of precise geodetic levelling data between 2000 and 2008. More than 4000 km of levelling lines between solidly constructed benchmarks were repeatedly surveyed by 1st-order levelling. Strict specifications for field work procedures and comprehensive corrections for systemic errors were applied to the levelling data. Furthermore, in order to account for the vertical deformations caused by four major earthquakes during the data span, coseismic offset corrections were computed and applied. The adjusted orthometric heights and vertical displacement rates of the benchmarks were obtained by least-squares estimation (LSE). The estimated standard deviations of the vertical rates are in the range of ± 0.41 mm/yr and ± 2.47 mm/yr, with a mean value of ± 1.64 mm/yr. These highly accurate results reveal that the most significant subsidence rate is observed in SW Taiwan at -109.4 mm/yr. Land uplift is widely observed in the Central Range and the Coastal Range, with the largest uplift rate of +29.4 mm/yr in SE Taiwan, at the convergence boundary of the Philippine Sea and the Eurasian plates.
All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Computers in Earth Sciences
- Earth and Planetary Sciences (miscellaneous)