The depth of geological disposal of high-level radioactive waste (HLW) varies from country to country, but it is generally considered below 300 m underground. As one of the reliable methods to understand the geological characteristics of these deep areas, the site investigation through drilling is recommended. This paper deals with multidisciplinary research that evaluates the geological characteristics of the site using deep drilling. The deep drilling is 750 m, which is higher than the planned disposal depth. Prior to drilling, literature and surface geological surveys of the target area were conducted, and during drilling, real-time measurement of excavated information for obtaining drilling information, circulating water management and chemical composition through a closed system were monitored. After drilling, field tests such as geophysical borehole logging, deep groundwater sampling, constant pressure injection test, and hydraulic fracturing test were performed. Analysis of the recovered drilling core from a geological point of view such as age dating, rock formation and structural geological analysis, and from geochemical perspectives such as concentration of major/ minor cationic elements, major anions, and trace elements along with the water quality parameters pH, DO, Ec, Eh, etc., from geothermal perspective such as thermal conductivity and coefficient of thermal expansion, from rock mechanical aspects such as physical and mechanical properties of intact rocks and joints, joint distribution, etc. Deep drilling has been completed with 2 holes for granite and 2 holes for sedimentary rocks, and further drilling for gneiss and sedimentary rocks is in progress.

Large earthquakes with (MW > ~ 6) result in ground shaking, surface ruptures, and permanent deformation with displacement. The earthquakes would damage important facilities and infrastructure such as large industrial establishments, nuclear power plants, and waste disposal sites. In particular, earthquake ruptures associated with large earthquakes can affect geological and engineered barriers such as deep geological repositories that are used for storing hazardous radioactive wastes. Earthquake-driven faults and surface ruptures exhibit various fault zone structural characteristics such as direction of earthquake propagation and rupture and asymmetric displacement patterns. Therefore, estimating the respect distances and hazardous areas has been challenging. We propose that considering multiple parameters, such as fault types, distribution, scale, activity, linkage patterns, damage zones, and respect distances, enable accurate identification of the sites for deep geological repositories and important facilities. This information would enable earthquake hazard assessment and lower earthquakeresulted hazards in potential earthquake-prone areas.