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Conference Paper
Mulwa JK, Soengkono S. "Application of magnetic method in geothermal resource exploration-A case study of Rotoma-Tikorangi geothermal prospect.". In: 1st KenGen/IAEA geothermal conference in Kenya. Intercontinental Hotel, Nairobi, Kenya: Kenya Electricity Generating Co./IAEA; 2002. Abstract

Rotoma-Tikorangi geothermal prospect is situated about 26 km northeast of Rotorua in New Zealand. It is associated with Okataina Volcanic Centre in the Taupo Volcanic Zone. A low level airborne magnetic survey (760 m a.s.l) covering the Rotoma-Tikorangi prospect was undertaken by staff of the Geothermal Institute in 1984. Detailed analysis of the aeromagnetic data carried out as part of the present study showed that some residual total force magnetic anomalies are independent of terrain effects. Positive magnetic anomalies are probably due to young rhyolites whereas negative magnetic anomalies are due to hydrothermal alteration. A three dimensional (3-D) magnetic interpretation indicated that hydrothermally demagnetized rocks associated with Rotoma-Tikorangi geothermal prospect have variable thickness ranging between 800 and 1250 m and dip towards the north. The geothermal prospect is characterized by concealed outflow. The results of this study also suggest that the Rotoma-Tikorangi geothermal prospect extends further to the east of a resistivity boundary delineated from previous studies. Detailed modeling of the demagnetized anomalies along respective flight lines is recommended as a follow-up to this study, to determine more accurately the extent of the hydrothermally demagnetized rocks.

Journal Article
Mwega BW, Mati BM, Mulwa JK, Kituu GM. "Application of electrical resistivity method to investigate groundwater potential in Lake Chala watershed." International Academic Research for Multidisciplinary. 2015;3(7):396-403. Abstract

A geo-electrical investigation was carried out in Lake Chala Watershed in Kenya to determine the roundwater potential of the area. The Vertical Electrical Sounding using schlumberger configuration with a maximum current electrode spread varying from 250 320m and potential electrode spread of 25m was utilized to provide information of the aquifers and subsurface lithology. A total number of 50 VES were carried out. The data obtained were interpreted by computer iteration process. Interpreted results revealed four to six distinct subsurface layers which comprised of top soil (clay, sandy clay soil intercalated with silt, sand and gravel)
, highly weathered ryholite, and moderately weathered basalt volcanic ash, highly weathered fractured basalt, weathered basalt, slightly fractured dry and fresh basalt and basalt basement rock layers. The results showed that the auriferous layer was composed of highly weathered fractured basalt, moderately weathered basalt & volcanic ash and weathered basalt geological material. The layer had a resistivity range of 40 to 200 and a thickness range of 1.38 to 91m. The results showed that lake chala watershed have high groundwater potential which can be exploited as an alternative source of water in the area.

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