Sunda and Sumatra Block Motion in ITRF2008

Abstract

The Southeast Asia region is mostly surrounded by active subduction zones in which the Australian plate, the Indian plate, and the Philippine Sea plate submerges beneath the continental plates and blocks. The Sunda block covers the large part of the Southeast Asia region, which comprises of Indochina, the South China Sea, the northeastern part of Sumatra, Borneo, the northern part of Java, and the shallow seas in between. We collect the GPS data in the whole Southeast Asia region for the period from 1994 to 2016, and process the original carrier phase data of GPS using GAMIT/GLOBK 10.6 to obtain the velocity field in the International Terrestrial Reference Frame, ITRF2008. The velocity field thus obtained is utilized to update the Euler rotation parameters of the Sunda block in ITRF2008, and model the long-term slip rates between the adjacent plate and blocks. In this study, we model the Sunda block and the Sumatra block together with the Australian plate by using TDEFNODE. The estimated Euler pole parameters of the Sumatra and Sunda blocks are estimated as their locations at (37.4°S, 106.8°E) and (46.2°N, 89.4°W), respectively, and their angular velocities of 0.371°/Myr clockwise, and 0.327°/Myr counter clockwise, respectively. These parameters result in the slip rate of the Sumatra fault with magnitude of ~9 mm/yr.