Heat Flow Measurements Under Some Lakes in North Island, New Zealand.

Abstract

The measurement of natural heat flow in New Zealand has been chiefly concerned with detailed surveys of the main geothermal areas (Fig. 1); the techniques used have been described by Dawson (1964) and Dawson and Dickinson (1970). In addition, the regional pattern in the North Island has been sketched from drill-hole measurements at 23 sites (Studt and Thompson, 1969). No measurements have been reported from the South Island. In view of the importance of heat flow as a geophysical paramter in regions of tectonic, seismic and volcanic activity, and the difficulties attending drill hole measurements, methods have been developed for the measurement of heat flow through the bottom of lakes. Many new Zealand lakes are deep enough for the temperature of the bottom water to be nearly constant for the greater part of each year, making it possible for the kind of technique by which heat flow is ordinarily measured in the deep ocean to be applied to continental New Zealand.