What is the main factor controlling the sukadana basalt in the sumatra back arc?

The mechanism of the presence of the Sukadana basalt in the back arc of Sumatra is still an enigma, especially since the Sukadana basalt has a wide coverage area in Sumatra Island and even the Sunda Arc. In this study, we used the published research data as the main contributor to an in-depth analysis to determine the mechanism of the presence of Sukadana basalt in the back arc. This study is supported by other studies from different regions around the world. These strengthen our conclusion that the emergence of Sukadana basalt on the surface is controlled by extensional deformations associated with the northwest-southeast-trending normal fault, which are formed by the mechanism of gravitational subsidence due to the movement of the Sumatra fault. In this study we suppose that the Nishimura fracture is a sinistral strike-slip fault as it is consistent with the Riedel shear model.