Geothermal Exploration in the Virunga Prospect, Northern Rwanda

Abstract

As part of a governmental policy for technical cooperation, Germany is poised to join partner countries in geothermal energy exploitation. Therefore, the Federal Institute for Geosciences and Natural Resources (BGR) on behalf of the Federal Ministry for Economic Cooperation and Development (BMZ) is carrying out the technical cooperation program GEOTHERM. As an example of the ongoing activities, results of studies carried out in the Virunga geothermal prospect in Northern Rwanda are presented.
The study area is located along the Western branch of the East African Rift System (EARS). Weak geothermal surface manifestations (e.g. hot/ cold springs with gas emanations) indicate the existence of a hydrothermal system. The aim of this study is to detect and assess potential heat sources with a multi-method approach. Remote sensing techniques, geochemical analyses, and geophysical measurements were applied in this first attempt.
Aerial photographs and satellite images were used for a high-resolution structural analysis to determine major fault zones. By performing a regional geophysical survey (Magnetotellurics, Transient Electromagnetics), an anomalous zone of low resistivities was detected in the vicinity of the Karisimbi stratovolcano, which is supported by the results of the geochemical analyses. Additional detailed geophysical investigations and gas measurements will provide insight to determine whether this anomaly is a magmatic intrusion or if the low resistivities are caused by a deep-seated fault zone.