Mapping deeply‐buried geothermal faults using microtremor array analysis

SUMMARY In this paper, the spatial autocorrelation microtremor array analysis is utilized to map deeply‐buried subtle faults that have primary controls on geothermal reservoirs. We identified a low‐velocity anomaly which is approximately 50 m wide at about 550–1400 m deep. A well drilled based on this anomaly later successfully produced hot water and further proved that the low‐velocity anomaly was caused by a highly fractured zone at depths from 700 to 1500 m. Our results clearly demonstrate that the microtremor survey method can be effectively utilized to map deeply‐buried faults and structures for geothermal energy exploration. The most effective way to increase the drilling success rate and, hence reduce the geothermal exploration risk, seems to be the development of new exploration methods and the integration of various geophysical technologies.