ANALYTIC SIGNAL AND RESERVOIR MODEL OF HATUASA-TALANGHAHA HOT SPRING, TULEHU, AMBON, INDONESIA BASED ON MAGNETIC DATA INVERSION

Abstract

The earth magnetic field study has been carried out in Suli and Tulehu, Ambon island to study the geothermal systems that apply in the region, specifically the reservoir model in the Hatuasa and Talanghaha hot springs. These hot springs are located on the fault line, including the Banda and Banda-Hatuasa faults, southwestnortheast. The study was conducted by subsurface inversion modeling after performing an analytic signal analysis of magnetic data. The total magnetic field intensity in the geothermal regions of Suli and Tulehu ranges from -656 nT to 310 nT, which is dominated by high anomalies in Tulehu. Meanwhile, the reduce to pole (RTP) magnetic anomaly ranges from -1069.20 nT to 662.78 nT, which is dominated by low anomalies, where the Haasa and Talanghaha hot springs are at low to middle anomalies. The analytic signal analysis of magnetic data clearly shows the geological boundaries in the study area. Inversion modeling of magnetic anomaly produces contrast susceptibility of rocks ranging from -0.042 SI to 0.043 SI. The reservoir layer as a place for geothermal fluid under the Hatuasa - Talanghaha hot springs is generally associated with low susceptibility contrast at depths reaching 500 m-1000 m. The cap rock is 500 m deep with a susceptibility value of 0.0035 SI-0.0065 SI and the heat source is thought to originate from igneous intrusion in the study area.