THE INFLUENCE OF MOUNT SINABUNG ERUPTION ON THE GEOTHERMAL IN TINGGI RAJA SIMALUNGUN

Mount Sinabung is a Pleistocene-to-Holocene stratovolcano, and its 2010 eruption was the first active activity after having been dormant for a long time. Enhanced pressure, intensity, and thermal energy of Sinabung activities hit several geothermal resources and triggered Tinggi Raja geofluid in Simalungun. This study aims to identify Sinabung eruption influences the appearance and point-transfer movement of geothermal features in Tinggi Raja. This research method builds a field model analysis (FMA) by integrating the quantitative and qualitative approaches focused on historic earthquakes activities (HEA) from the Center of Volcanology and Geological Hazard Mitigation (CVGHM), time-series satellite observation of land surface change, and land surface temperature, the residual anomaly of the geothermal reservoir, high altitudes and chemical-drop in pH, and point-transfer movement. HEA shows fluctuating activities in eruption level or Volcanic Eruption Index (VEI) scale. FMA offers fewer residual anomalies from Southwest to Northeast in 100 m–600 m coverage 5 km2 underground than pre-hypothesis indicates the anomaly zone associated with the fracture zone; however, the lithology of the geothermal system is categorized as limestone rock and has no active faults. It indicates a low magnetic field anomaly in geothermal resources that does not correlate volcanic manifestation to geothermal trigger. Distance, type, and felt volcanic earthquake and eruption are less direct impact between the eruption of Mount Sinabung and the displacement of springs at Tinggi Raja.