| Abstract |
Locations of productive geothermal fields in the circum-Pacific area have been examined in order to identify natural conditions which may have helped in the development of geothermal fields at those locations. Preliminary examination indicates that these locations are near the lateral ends of several plate boundary segments, and in transverse zones which divide plates into several independent blocks 100-1000 km long. Examination of these locations by Pattern Recognition Technique suggest that these locations are near fumeroles and hot springs and near historically active volcanoes which erupted at least once in a century. Volcanic rock type and amount of rainfall in the area provide ambiguous results and do not appear to be crucial. Shear heating in these transverse zones may explain the excess heat flow and therefore the development of geothermal fields in these zones. Available heat flow data in Japan support this hypothesis. |