Review of Regional Geological Structures on the Appearance of Geothermal Manifestations in the “Neck” Region of Western Sulawesi Island

Abstract

Palu-Koro fault is a major fault in western neck of Sulawesi Island. It is shown by Mw 7. 5 struck the area in 2018. Its trace can be observed by the appearance of surface ruptures. We recorded their geographic coordinates and observed the geological conditions of the surface such as structures form, properties of rocks, and physical properties of local hot springs. Then we conducted a qualitative interpretation by integrating field observation data on several References related regional geological structure of the area. From the results of the review, we suspect that there is a very close relationship between the activities of the geological structure and the appearance of several hot springs in the neck region of western Sulawesi. This is evidenced by the presence of 7 points of manifestation with the same pattern as the direction of orientation of the main fault, which is relatively north-south. However, one of requirements of the manifestation appearance on the surface is the existence of the fractures as up flow channels of geothermal fluids. Heat source is interpreted to come from intrusive igneous rocks as hot rocks conducting heat to the aquifer which heats the hydrological system around the area. We conclude that geothermal manifestations in the western neck of Sulawesi Island are tectonic geothermal related to the geological structures and not to the volcanic activity.