Subsurface Structure Identification Using Gravity Field Measurement Data Analysis in Songa Wayaua Geothermal Prospect Area

Abstract

Geothermal prospective area has surface signs, often called surface manifestaations. Prospective area needs to be analyzed using several techniques in terms of geological structure and its interconnection with subsurface structure. The structure can be hypothesized as the geothermal fluid path and become consideration of identification permeable zone that can produce large outcome of drilling results. Songa Wayaua geothermal field is located in Bacan Island, North Maluku Province, Indonesia. Geothermal manifestations are found scattered along the coastal plains from the Songa area to Bukit Langsa, and a hot spring is also found on the Wayaua beach in the southern part. Geological structure on Songa Wayaua geothermal field from previous research still unclear whether geological subsurface structure is related with its surface structure based on data observed. FHD and Euler deconvolution analysis done with a good result corelating subsurface feature with surface structure. FHD and Euler deconvolution result are mostly giving the same result based on horizontal anomaly interpretation. Tawa Fault, Banda-Hatuasa Fault, Sibela Fault and Bukit Bibino Fault are shows good corelation structure with anomaly majority occurred in 0 – 500 meters depth. Those structures probably are permeable structures that could control the existence of surface manifestation, both upflow and outflow.