Geodetic, Gravity & Magnetics

[GM-02] Estimation of time-series surface displacements in Taiwan using interferometric SAR analysis

*Shoki Hiranaka¹, Kazuya Ishitsuka¹, Weiren Lin¹ (1. Kyoto University (Japan))

Surface displacement monitoring is important for understanding groundwater activity and strain accumulation and exploitation of natural resources. Taiwan orogeny has been formed with arc-continent collision between the Eurasian and Philippine Sea plates. The Philippine Sea Plate is moving northwest at the rate of about 80 mm/year. However, the Ilan Plain, located in Northeast Taiwan, represents a transition zone between oblique collision and backarc extension, implying complicated displacements in the Ilan Plain. Therefore, in the Ilan Plain, multiple mechanisms of surface displacements such as the subduction of the Philippine Sea Plate, the effects of backarc extension and the anthropogenic activity like a pumping of groundwater are expected to have occurred. In this study, we estimated surface displacements in Taiwan using InSAR time-series analysis of Sentinel-1 IWS data acquired between October 2017 and October 2019. We further characterized the temporal pattern of surface displacements by a seasonal and long-term temporal model, which were used to interpret the mechanisms of the estimated surface displacements. The time-series displacements show continuous pattern about 30 mm/year occurred in the western and eastern Taiwan during the period. The annual velocities of the displacements in the Ilan Plain were comparable with those reported previously. We confirmed the displacement rate of our result is smaller than the rate of previous research. We compared with GNSS data to validate our results using Root Mean Square Error (RMSE). RMSE values show about 10 mm and this means our results are effectiveness.