| Title | Resistivity Survey of Motuoapa Springs, New Zealand |
|---|---|
| Authors | Bibby, H. M., Risk, G. F. and W. J. P. MacDonald |
| Year | 1991 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | |
| Abstract | Resistivity measurements have been made with Schlumberger electrode arrays of spacing = 500m and m over both land and water throughout a 15 x 20 region around Motuoapa at the southern end of Lake Taupo, New Zealand. A low resistivity zone with apparent resistivity values as small as 5-10 was found at Motuoapa encompassing an area of at least 8 which includes the region of minor hot springs at the edge of the lake. The resistivity anomaly for at least a under the lake and, together with a broad offshore magnetic low, indicatesthat a large part of the Motuoapa thermal system lies under the lake. High resistivity values measured to the south-west of Motuoaparule out the possibility of a hydraulic connection between the Motuoapa thermal system and the Tokaanu-Waihisystem which lies 10 away. High resistivity values measured at Te Rangiita suggest that unconfirmed informal reports of thermal activity there are unlikely to be true. Low to intermediateresistivity values observed along the valleys of the TaurangaTaupo and Tongariro rivers to the south-east are thought to be caused by clay-rich sediments lying close to the surface in the valleys and to be unrelated to thermal activity. Very high resistivity values are observed over the shallow greywacke basement in the elevated south-easternpart of the region. |