As mentioned earlier, GPS campaigns were carried out more frequently from 2005 onwards at all GEODYSSEA/THAICA GPS points in Thailand, to capture the 3D post-seismic signals. Although the campaign-derived heights in the post-seismic time series remain noisy
(Fig. 4, data points right of the dashed vertical line) they do indicate downward motion (−3.9±2.1 mm/yr at CHON and−12.7±4.2 mm/yr at BANH, assuming a linear trend at both sites). At CHON, almost all (8/9) re-measurements were made using an identical antenna setup and the linear vertical trend for the post-seismic (2005–2008) period does indicate significant downward motion. Although the BANH re-measurements were carried out with multiple antenna types (possibly introducing artificial vertical position shifts
due to different antenna phase centre behaviours) downward vertical motion here also seems to initiate after December 2004.