Author(s): Cyrke A.N. Bujung, Donny R. Wenas
North Sulawesi Indonesia has many natural resources that can be used as geological tourism object, including Lake Tondano and Lake Linow. In addition to the natural beauty of the lake itself, there are also geological phenomena in the form of the appearance of many geothermal manifestations, which indicate the existence of a permeable zone between the two areas. It is interesting to examine whether there is a geological structure that connects the two lakes which can then be used as information and recommendations for the development of geothermal energy exploration in North Sulawesi. This study aims to determine the existence and direction of subsurface geological structures based on gravity anomaly data, and the presence of surface geological structures based on line density in the area between Lake Tondano and Lake Linow. The gravity method is used to obtain information about the geological structure of the area between Lake Tondano and Lake Linow which is characterized by contrasting gravity anomalies, which are then interpreted as geological structures in the form of faults. In addition to the gravity method, the lineament method is also used to determine the surface geological structure of the area between Lake Tondano and Lake Linow. The results showed that there was a fault in the Lake Tondano area and its surroundings which was trending east-west to southeast. This is known based on the distribution of bouguer anomaly values that increase towards the eastern part of Lake Tondano with a value of 154 - 168 mGal. Based on the analysis of lineament density, it is known that the surface geological structure around Lake Tondano extends in the southeast-northwest direction which is an extension of the structure between Lake Tondano and Lake Linow. The results of this study conclude that the development trend of geothermal energy exploration extends from the northwest of Lake Linow to the southeast of Lake Tondano.