1. Magnetic and Gravity Methods for Geothermal Exploration Dr. Hendra Grandis Geophysics - ITB
2. Ql : existence of deep structure, i.e. intrusive body or caldera structures Qt : geometry of those above (the upper structure must be closely defined) high or low anomaly gravity (covers low and high magnetic areas) Ql : ascending thermal fluid (and / or descending cold water) Qt : ? high or low anomaly self-potential (across high and low resistivity areas) Ql : can be associated with thermal fluids upflow and outflow zones Qt : shallow resistivity structure low anomaly Schlumberger resistivity mapping and sounding (concentrated in the area between broad magnetic low and high) Ql : can be associated with thermally altered zones Qt : geometry (?) low anomaly Aero- or ground magnetic (covers a large area) interpretation expected anomaly method and survey procedure
3. Probable sequence of geophysical exploration methods used to investigate young volcanic geothermal prospect (revised from Sudarman, 1983) Ql : permeable zones Qt : ? high anomaly micro-seismics (M< 3) Ql : can be associated with thermal fluids upflow and outflow zones Qt : deeper resistivity structure low anomaly Magnetotelluric sounding Ql : uprising or horisontal thermal fluid movement, if depth to resevoir is relatively shallow Qt : defined the upper structure high anomaly Thermal gradient and anomalous temperature (to figure out the cause of low resistivity layer) interpretation expected anomaly method and survey procedure
The gravity data generally follow the trend of topography. The most prominent feature is the presence of a large elliptical high located about 2 km southeast of the lake, modeled by Tripp et al. (2002), suggested it represent shallow granodiorite.
The gravity data generally follow the trend of topography. The most prominent feature is the presence of a large elliptical high located about 2 km southeast of the lake, modeled by Tripp et al. (2002), suggested it represent shallow granodiorite.
