Electrical Imaging the Kerepehi Low Temperature Geothermal System, New Zealand

Abstract

In-loop transient electromagnetic (TEM) data has been collected from 105 sites in the Kerepehi area to investigate the relationship between the shallow resistivity structure and warm seeps mapped in the area. The area is generally conductive which reflects the clay-rich sedimentary environment, with a low resistivity anomaly (<10 ohm-m) close to Kerepehi Township. This anomaly intensifies between 100 and 200 m below ground and may be associated with thermal fluids interacting with uplifted basement rock and fault structures.
Ten thermal springs (current or historic) are mapped in the Kerepehi area, with many of these springs located in a line, on the eastern side of the low resistivity anomaly. This may indicate that a shallow permeable structure may be facilitating near-surface flow of thermal fluids to the surface.