| Title | Three-Dimensional Thermal Structure in the Tohoku District, Japan Estimated from the Activity Index |
|---|---|
| Authors | Yota SUZUKI, Hirofumi MURAOKA, Hiroshi ASANUMA |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | brittle-plastic transition, brittle-plastic transition, activity index, Tohoku |
| Abstract | Subsurface three-dimensional thermal structure in the Tohoku District, Japan was estimated from the shallow-depth hydrothermal data in order to evaluate exploitable potentials of the next-generation geothermal energy. One of the future targets of geothermal development in Japan is supercritical geothermal reservoirs which are expected immediately beneath the brittle-plastic transition (BPT). The temperature profile of the well WD-1a in Kakkonda encountered a temperature inflection point at 380 ËšC and 3100 m depth. The temperature inflection point at 380 ËšC is considered to denote the BPT on granitic crust in contraction tectonic fields. Strong correlation between the 380 ËšC isothermal depth and the bottom of seismicity clouds is demonstrated in this study. This result indicates reliability of the subsurface three-dimensional thermal structure in the Tohoku District, Japan providing an important indicator for the accessible next-generation geothermal energy beneath the BPT. |