The purpose of this research is to explore the mechanism required for the generation of earthquake vibration on the propagation velocity of the crack in fault plane. In this research, the impact splitting tensile tests of mortar and granite were carried out, and the propagation velocity of the crack was visualized and obtained by image analysis using ultra high-speed video camera. A relationship between the impulse which is impact loading and propagation velocity of the crack was observed. There appears to be a critical state in which propagation velocity does not increase, even if impulse is increased over it. It was proven to converge in 2.6 km/sec. Next, the mechanism of the development of the dynamics of the crack by the impulse was examined from displacement vector and Particle Image Velocimetry (PIV) analysis.
