Geologic Risks in the Chugoku District(<Theme>Chugoku Branch Issue)

Carboniferous to Quaternary sedimentary rocks, igneous rocks and metamorphic rocks are distributed in Chugoku district, western Japan. Weathered these rocks cause huge disaster because they have characterized structural elements such as joint, fault, fold and foliation. Especially the regions where weathered granite (we called it "masado" in Japanese) distributes have frequently experienced major disasters. Recently environmental pollution caused by heavy metals including in a rock and acid water has been increasing. We must make thorough investigation to seize the geologic risks. That will lead to provide high-quality infrastructures