Japan issues advisory over possible Nankai Trough earthquake

TOKYO -- Japan on Thursday said the possibility of a huge earthquake over a wide swath of central and western parts of the country has increased relative to normal conditions following a magnitude 7.1 temblor off Miyazaki prefecture on the southern island of Kyushu earlier in the day.

Following the afternoon quake, the Japan Meteorological Agency launched investigations into its possible relationship to a potential Nankai Trough earthquake, which experts have warned for years could cause huge loss of life and property across a wide stretch of central and western Japan. The trough is a marine trench running along part of the south of the Japanese archipelago.

The agency issued its Nankai Trough Earthquake Extra Information for the first time ever on Thursday evening. An accompanying government advisory said the "possibility of a large-scale earthquake is considered to be relatively higher than under normal conditions." According to the agency, the large earthquakes have taken place every 100 to 150 years in central and western areas of the country.

The government has previously said there is a 70% chance of such an earthquake within 30 years. And while Naoshi Hirata, an earthquake expert and emeritus professor at the University of Tokyo, said at an agency news conference that "the probability is multiple times higher than usual" after the Miyazaki earthquake, it remains "an event of one in a multiple hundred times." Still, he urged people to be prepared.

Prime Minister Fumio Kishida also called on the public to check their earthquake preparations and "be ready to evacuate immediately if an earthquake occurs."

There have been no reports so far of major damage from Thursday's 7.1-magnitude quake and the small tsunamis it