ANKARA: Japan's state weather agency continued to maintain a "megaquake advisory" on Sunday urging the citizens to keep up their guard against a possible mega-earthquake in the Nankai Trough along the Pacific coast. The Japan Meteorological Agency (JMA) had issued the advisory on Thursday after a magnitude 7.1 earthquake struck off Miyazaki Prefecture in southern Japan, public broadcaster NHK reported. It was followed by another 6.8 magnitude earthquake that hit northern and northeastern Japan on Saturday. The agency, however, said that no irregular changes in the crustal strain have so far been observed. It is the 'first such advisory for areas around the Nankai Trough,' stretching from southwestern to central Japan. The possibility of a "massive' earthquake in the Nankai Trough is "higher than usual," the weather agency warned. It called on people to remain alert, as subsequent quakes with a maximum seismic intensity of lower 6 could strike over a period of roughly a week. The agency officials, howev er, explained that the advisory does not mean that a quake will definitely strike within a certain timeframe. However, they have asked 707 municipalities in 29 prefectures, extending from around Tokyo in the east to Okinawa in the south, to check their disaster preparedness. The government has advised households with infants, the elderly and people with disabilities to consider evacuating voluntarily. Source : Anadolu Agency