Abstract: The authors summarized researches on the Tohoku off-pacific-coast M9 earthquake and its effect on ground deformation and tsunami. Review was also given on the seismotectonic setting under the framework of plate tectonics, geographic environment, historical activities of M8-class earthquakes in Tohoku off-pacific-coast, Kanto area and Tokai area, with the up-to-date progress in prediction on future earthquake activity of M8 class in Tokai area. The authors also reviewed the status and problems to be solved in mid-to-long-term prediction on earthquake occurrence and suggested important research topics in earthquake science. Lastly, suggestions are also given for avoiding mistakes in engineering design and the related risk assessment.