| Abstract |
In the middle reaches of the Kurobe River, Central Japan, there is a wellknown geothermal area. During the construction of the tunnel of Kurobe Jobu Railway between Sennin-dani and Azohara Spa, the temperature in the tunnel increased and at last reached over 160°C of wall rock temperature (Matsui and Yoshida, 1962). There were not so many hot springs and fumaroles in the tunnel, therefore, the rock body is considered to be so-called "hot dry rocks". Temperatures of the wall surface show 98°C at maximum even now, and their high values correspond to a fracture zone of the rock body. |