Volcan Casita, Nicaragua: A GIS Based Geothermal Assessment

Abstract

Ram Power’s Volcán Casita 100 km2 geothermal concession, located in northwestern Nicaragua, incorporates part of inactive Volcán Casita and La Pelona caldera. Tectonics are controlled by the subducting Cocos plate and local structural control is related to northeastwardly striking sinistral R’ shears, which include the La Pelona fault system. Work done by Sinclair Knight Mertz (SKM) indicates a resource of >=250o C with a potential production capacity of >137 MWe @ 90% probability for 20 years, making this an attractive exploration target. It is not uncommon to begin a geothermal exploration project with disparate data ranging from analog maps to state-of-the-art digital data sets. This was the scenario recently at Ram Power as the curtain was drawn on the Volcán Casita geothermal development project, where a geographic information system (GIS) was used to integrate, visualize, and interpret all data for thr project. Initially analog maps and graphics were scanned into raster formats. These were then georeferenced to a common coordinate system and datum. Some digital raster data were ready for immediate incorporation into the GIS system. Other data, such as lithologic units and faults from a paper geologic map, were digitized into vector files. The GIS also facilitated the direct use of multispectral satellite imagery, airborne synthetic aperture radar data, and a digital elevation model which supported further geologic evaluation. The GIS allowed the integration, processing, visualization, and analysis of the data for the Casita Volcano project creating a platform from which drilling decisions could be made with a reasonable level of confidence.