Simple deformation modelling using GNSS GPS data at Minahasa subduction

Abstract

North Sulawesi Trench or Minahasa subduction area is a subduction zone between the oceanic crust of Sulawesi Sea and the North Sulawesi Arm located at the triple junction in Eastern Indonesia. This subduction activity causes the North Arm of Sulawesi as an earthquake-prone area. Tectonic activities in the region can be studied through geodetic monitoring using GNSS GPS observations and by physical modelling from the rate of geodetic geometric results. Yearly GNSS GPS campaign have been conducted in the region from 1997 to 2008 and continuously observed by BIG from 2008 to 2016 using permanent GNSS GPS stasion. The coordinates of monitoring stations realized in ITRF-2008 provide residual RMS values of 3.13 mm, 4.15 mm and 7.26 mm for the northern, eastern and vertical components, where this indicates a high degree of accuracy. A simple estimation profile using GNSS GPS data based on the Okada elastic equation for the subduction zone shows a subduction movement ranging from 4 to 5 cm/yr with a locking depth of about 50 km, a dip 300 and ending in the post-seismic phase due to the sequence of earthquakes occurring in Minahasa since January 1, 1996 Mw 7.9 to 16 June 2002 Mw 5.9.