Daniel N. Nyakundi^1,, Erick R. Nyakundi¹, Solomon Namaswa²

Gravity data analysis is a widely applied technique for imaging the Earth’s subsurface. This study interprets satellite-derived gravity data over Silali geothermal field to delineate subsurface structures and identify zones favourable for geothermal resource development. Standard reduction procedures were applied to raw gravity data to obtain a complete Bouguer Anomaly (CBA) map. Residual gravity anomalies were extracted using Butterworth and bandpass filters in Oasis Montaj. The anomalies predominantly trend in North-South, Northwest –Southeast directions, forming grabens and horsts that localize magmatic intrusions and geothermal up flow zones. Further enhancement using upward continuation, analytic signal, Power spectrum analysis, and located Euler deconvolution revealed intermediate and deep seated structures. Spectral analysis indicates sediment thickness between 1500 and 5300 metres sufficient to sustain geothermal energy systems. The analytic signal delineates potential intrusions and faults, particularly in the central, South-East, and Western zones. Euler deconvolution solutions (structural index = 0.5, 1.0, 2.0) cluster mainly North and West of the caldera, outlining dense magmatic bodies and fault-controlled features influencing geothermal fluid flow. These findings provide valuable insights for targeting drilling locations in the Silali geothermal system.

Gravity anomalies, geothermal, delineate, power spectrum analysis, Euler Deconvolution