Resistivity Tomographic Imaging of the Qualibu Caldera, Soufriere, St. Lucia

The Qualibu Caldera, Soufriere, St. Lucia is a large topographic depression formed by downfaulting. The Caldera structure has been long investigated for geothermal power generation. It houses the Sulphur springs geothermal system as evidenced by natural manifestations of hot springs and micro-seismic activity. In 1974 several lines of dipole-dipole resistivity data were collected in the area. One of the lines running through sulphur springs was interpreted by using forward models to generate a best-fit model. Using modern 2D resistivity inversion algorithms, the resistivity data collected in 1974 have been re-analyzed and interpolated into a 3D image system. The results have agreed very closely with geologic and borehole data in the area and reveals conductive features reminiscent of a convecting geothermal system.