Dr. Hiroo Kanamori has made an epoch-making progress on the study of great earthquakes through the establishment of analytical method to understand quantitatively all over the rupture process of a great earthquake making full use of seismogram. This study has ushered in a new era in seismology and had a significant impact on the development of geophysics. He has made practical proposals on how to mitigate earthquake hazards based on the knowledge gained through basic studies and contributed to building up and conducting earthquake hazard mitigation systems.