Low probability natural phenomena and crustal movement on high level radioactive waste geological disposal

The differential stress of granites was measured under the conditions of dry and 100 MPa at room temperature. The physical properties of three samples in the earthquake swarm zone in Hyogo prefecture were studied. One of origin of earthquake might cause very small compressive strength of sandy are nite in the Tamba zone. The extrusion age of Aso third pyroclastic flow was determined by K-Ar dating. The extraction age was estimated about 120 to 130 thousand year ago. AT volcanic ash originated by Kyushu did not change the forest structural species. (S.Y.)