| Title | Microearthquake and Resistivity Imaging of the Longonot Geothermal Prospect, Kenya |
|---|---|
| Authors | S. Onacha, P. Malin, E. Shalev, S. Simiyu and William Cumming |
| Year | 2007 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | |
| Abstract | This paper presents the results of microearthquake (MEQ) and resistivity studies at the Longonot geothermal prospect in Kenya. The data used was acquired by new MEQ instruments specifically designed to work under the field conditions in Kenya. The results show a good correlation between resistivity, location of microearthquakes, volcanic activity, fluid flow and structures. Analysis of the resistivity data shows high anisotropy close to the boundaries of low and high resistivity anomalies which are also associated with the location of microearthquakes. Based on the data analysis and interpretation, one well has been located in an interpreted fracture zone. The fracture zone is bound by areas of higher resistivity which are attributed to lower fracture porosity and probably lower temperatures. Such areas of deep high resistivity should not be targets for drilling exploration wells. An important finding of these studies that has international implications in the way MEQ data is acquired for geothermal exploration is that MEQ data loggers must be deployed appropriately close to the fracture zone. When the seismometers are located far away from the fracture zone, the MEQ signals are often attenuated before they arrive at the recording stations. This can lead to the erroneous conclusion that geothermal prospects are aseismic. |