Distribution of earthquake in subduction zone and calculation of subduction angle in the Central Sumatera based on earthquake data period 1967-2016

This research is about the distribution of earthquake in subduction zone and calculation of subduction angle in the central Sumatera period 1967-2016. The data used in this research is earthquake data period January 1, 1967 until December 31, 2016 associated with the subduction zone. Research region consist of West Sumatera, Riau and North Sumatera. This region is made by following the slope of the subduction zone using GMT 5. Graphic of the relation between distance and depth every earthquake event is processed using polynomial method to be able to know the trend of subduction zone in this region. While, to find out the subduction angle in this region, calculation with the first derivative of the parabolic equation have been do. The results show that the subduction trend within 50 years is calculated in 10 years interval, the displacement that occurs is not too visible. But, it shows that the longer, the more subdued. While the angle of subduction at 50 km, 100 km, 150 km and 200 km respectively is 22.68°, 35.73°, 42.89° and 47.72°. This shows that the deeper, the larger subduction angle is formed.