Japan, one of the most earthquake-prone nations on earth, issued its first-ever “megaquake advisory” last week after a powerful quake struck off the southeastern coast of the southern main island of Kyushu. Japan, one of the most earthquake-prone nations on earth, issued its first-ever “megaquake advisory” last week after a powerful quake struck off the southeastern coast of the southern main island of Kyushu. Environment Phys.org – latest science and technology news stories