Data Analysis Geophysics Investigation With Geomagnetic Method For Geothermal Exploration Dolok Marawa, Area Sumatra Utara

Abstract

Energy is a very important requirement for human being in order to fulfill their activities. Geothermal energy is primary energy, non-oil that is renewable. Geothermal classified as eco-friendly and small B-3 waste potency. Generally, the availability of geothermal in Indonesia related with magmatic and volcanic area as its thermal source. Rise of geothermal is reflected by surface thermal manifestation. In observation area, that is Dolok Marawa, there is wellspring manifestations which indicate that in particular depth of underground, geothermal was exist. Geothermal system composed by parameters, there are: thermal source, reservoir, covered rock, and fluids. To locate the geothermal position around research’s area, geophysics investigation was use with geomagnetic method. The procedure of geomagnetic research includes, topography measurement, bottom spot determination, data collection, data processing, the collecting method of magnetic data, data processing result and magnet anomaly map digitations. Geomagnetic interpretation performed by qualitative and quantitative. The qualitative interpretation of this investigation related with contour map of magnetic anomaly and anomaly profile of magnetic. Qualitatively, learned object is modeling which yielded by mathematic approach calculation in manual and computerize. The result of geomagnetic investigation in Dolok Marawa that is, rock susceptibility price of rock magnetic, profile of magnetic anomaly, and map of magnetic anomaly. The susceptibility price of magnetic in investigation area about 0 to 1 nT, it might caused by effect of local geothermal symptoms so that demagnetize occurred. The result of all five interpretation due to geomagnetic course, 2,3 and 4 course categorized as group of low magnetic anomaly, with value between -394 nT, -824 nT and – 330 nT, so that, it is predicted as prospect area for geothermal. Based on interpretation of magnetic anomaly map integrated with others integrated investigation, such as geological investigation, then, conclude that low magnetic area and intermediate, and rather low, with total magnetic value is less than -525 nT to -175 nT as area that related significantly with geothermal system formation and has a potency as geothermal area, that is western investigation area.