Fig. 4. Vertical land motions at CHON and BANH. Precise GPS height coordinates of both stations were corrected for seasonal variations estimated from 2005–2009 CGPS data at RYNG
(collocation distance 39.4 km with CHON) and CPNT near BANH (33.1 km collocation with BANH). Plots of GPS height time series, since the first campaign in November 1994 until
October 2004, reveal a combined inter-seismic and GIA uplift at both locations. Also shown are post-seismic height time series at both sites (at the right of dotted vertical lines marking the earthquake time). All GPS campaigns were conducted by the Royal Thai Survey Department and analyzed in cooperation with DEOS (Simons et al., 2007). Details on the computational process and the (verified) 1-sigma error bars are given in Simons et al. (2007). The post-seismic phase error bars at BANH are noticeably higher since they take into account (remaining) height offsets between the 5 different GPS antennas used (although antenna phase offset correction tables are used in the GPS processing). Still, the post-2004 downward trend of height is detected as in the case of CHON where almost always the same GPS antenna type (and setup) was employed