Deformation analysis of Mentawai islands based on observation GPS data 2013-2016

The islands of Sumatra accommodate the collision of the Indies-Australian plate pressing the Eurasian plate at a speed of 5-6 cm/yr at the boundary between the plates along the west coast of Sumatra (Natawidjaja, D.H., 2007). The oblique collision between the two plates formed a subduction zone in the western part of the island of Sumatra and a number of fault segments on the island of Sumatra. Subduction zones and cesareans segments that are formed actively move so often cause earthquakes in the region. Mentawai islands are located in the westernmost part of Sumatra and belong to the subduction zone of Mentawai Segment Mentawai Islands movement can be identified using GPS observation data. The data used are GPS observation data from 2013 to 2016 coming from Sumatran GPS Array (SuGAr) Network. The data is processed using software GAMIT / GLOBK 10.6. The results of the GPS data processing will be processed to produce velocity velocities and strain values of each GPS observation station used to observe deformation activity on the Mentawai Islands. The results of GPS observation data processing showed vector movement in Mentawai Islands referenced to Sundaland Block leads to the northeast on the northern part of the Mentawai Islands, heading southwest to the southern part of the Mentawai Islands, and heading north to the central part of the Mentawai Islands. The strain obtained from data processing showed that the Mentawai Islands experienced an interseismic phase in the north, a post-seismic phase in the south and a transitional phase in the middle.