A case history: 3-D gravity modeling using hexahedral element in Kinigi geothermal field, Rwanda

It is important for geothermal exploration to know regional subsurface structures. The gravity survey is often used to narrow down the promising area at the early stage of geothermal exploration. The gravity survey was carried out to estimate subsurface density structure in the Kinigi geothermal field, Rwanda, in September 2015. In order to interpret the gravity anomaly distribution, 3-D gravity modeling was done by using the new program based on Gauss-Legendre integration using hexahedral elements. As the result, the computed gravity anomalies showed high gravity anomalies in northwest, the northeast, and east-southeast of the studied field and low anomalies in the southwest side of the studied field as Bouguer anomalies. The area was characterized by normal contacts with main boundary trending NW-SE direction. This boundary was estimated as main fault in Kinigi geothermal field, Rwanda. The detected fault could be a better place for installing geothermal wells for future geothermal development in the region.