| Title | Development of Permeable Fractures in Geothermal Systems in the Japanese Islands - Two Contrasting Types of Geothermal Reservoir |
|---|---|
| Authors | Masakatsu Sasada |
| Year | 1995 |
| Conference | World Geothermal Congress |
| Keywords | fault, fracture, geothermal reservoir, Japanese islands, Kyushu, stress field, tectonics, Tohoku |
| Abstract | Permeable fractures developed in geothermal reservoirs are controlled by their tectonic environment and geologic structure. Accumulated surface investigations and subsurface borehole data in exploited geothermal fields suggest that development of permeable fractures are classified into two types in the Japanese Islands. A geologic framework of a geothermal reservoir is characterized by a high-angle normal fault system in central and southern Kyushu, and by fracture networks in Tohoku (northeast Honshu). The type of fractures is probably related to the regional and local stress fields, and the geologic development of their host rocks. |