Siberut Island Movement and Direction Monitoring Using SuGAR Data

Abstract One of the areas in the Mentawai Islands, especially Siberut Island, is prone to earthquake disasters. This is because Siberut Island is an area that is directly adjacent to the subduction zone. Activity in this subduction zone can cause deforma- tion, resulting in earthquake events. Deformation can be determined using GPS data from the SuGAr (Sumatran GPS Array) network. The data used is SuGAr station observation data within 365 days. Data processing uses auxiliary software, namely GAMIT/GLOBK. The result of data processing is the deformation velocity vector observed every month in 2019. The resulting velocity vectors show each station's direction and speed of deformation in the horizontal and vertical directions. Velocity vectors in the horizontal direction for each station tend to point to the northeast. It is consistent with the direction of subduction, where the Indo-Australian plate moves under the Eurasian plate to the northeast. As for the velocity vector in the vertical direction, some stations experienced uplift, and some stations experienced subsi- dence. The deformation velocity of each station varies, and the value is relatively small.