dc.description.abstract | This study used 52 SAR images from ERS during 1993-2000 and 21 SAR images from Envisat during 2005-2008 with PSInSAR method to discover the crustal deformation of Tainan region. The StaMPS method was employed to estimate and remove the influence of errors, then produced Line-Of-Sight mean velocity fields and time series to infer vertical motion of ground. The result shows that, during 1993-2000, the uplift pattern of Tainan tableland is highly correlated with time and topography, about 5-8 mm/yr relative to TN01 benchmark. And the west part of tableland, the Dawan lowland with high subsidence rate about –10mm/yr. From this data set, last 10 images after 1999 Mw=7.6 Chi-Chi earthquake didn’t present significant coseismic or postseismic effects until late 2000. From 2005-2008, the uplift pattern of Tainan region was different form previous, north part of Tainan tableland uplifted with 10 mm/yr which was 5mm/yr higher than the south part. Dawan lowland turned to uplift with 12 mm/yr. This phenomenon indicated that Tainan region experienced a transition of uplift. To understand when the transition began, single point LOS time series analysis was applied and compared to precise leveling measurements. Both measurements revealed the transition of Dawan lowland began from 2005. Furthermore, from LOS time series, 3 rapid uplift events were found at middle 2005, late 2006 and late 2008. To discuss the relationship between deformation and mud diapir, forward modeling with grid searching was utilized to elastic half-space spheroid sources. Before 2000, the topography correlated uplift pattern of Tainan tableland could be modeled by an ellipsoid centered at 3 km depth, but the 2005-2008 uplift pattern required a deeper and wider penny-shaped crack source across Tainan tableland and Dawan lowland. The difference of source model inferred the transition of uplift pattern was related to the migration of pressurized source. The interpretation of the source migration could be the active mud diapirism and based on published physical model results, the pop-up model could form with mud diapirism, this study then suggest active mud diapirism should be considered with current pop-up model.
| en_US |