Tokyo issued its first-ever "mega-quake warning" after a 7.1-magnitude earthquake struck its southern coast last week. Nobuhito Mori, deputy director of Kyoto University's Disaster Prevention Research Institute, tells CGTN Wednesday that while the risk of an even larger quake on the Nankai Trough is raised for the moment, the possibility of a mega-earthquake would be adjusted by the end of the week. He also said China would likely not be affected by tsunamis from Nankai Tonaikai quakes.