TOKYO — The Japanese government said Thursday there was a higher-than-normal chance of a major earthquake hitting a wide area of central and western Japan following a magnitude 7.1 earthquake that struck off the coast of Miyazaki prefecture in southern Kyushu early that morning.
The afternoon quake prompted the Japan Meteorological Agency to launch an investigation into whether it was linked to a Nankai Trough earthquake, a submarine trench that runs along the southern part of the Japanese archipelago, which experts have long warned could cause extensive loss of life and property across a wide area of central and western Japan.
On the night of the 18th, the Japan Meteorological Agency released its first special information regarding the Nankai Trough earthquake. The accompanying government warning stated that “the possibility of a large-scale earthquake occurring is considered to be relatively higher than normal.” According to the agency, large earthquakes occur in the Midwest every 100 to 150 years.
The government has previously said there is a 70% chance of such an earthquake occurring within the next 30 years. Earthquake expert and Tokyo University Professor Sunao Hirata said at an internal press conference following the Miyazaki earthquake that “the probability of an earthquake occurring is several times higher than normal,” but added that “it is only about one chance in several hundred,” and urged the public to prepare.
Prime Minister Fumio Kishida also called on the public to check their earthquake preparedness and “be prepared to evacuate immediately if an earthquake occurs.”
There have been no immediate reports of major damage from Thursday's magnitude 7.1 earthquake and the small tsunami it triggered. Chief Cabinet Secretary Yoshimasa Hayashi said “no reports of abnormalities have been received” at nuclear power plants or related facilities in the area.
Immediately after the Miyazaki earthquake, the Japan Meteorological Agency called for a week of vigilance due to the increased probability of a major earthquake occurring, but JMA officials repeatedly stressed that even after the certain period had passed, such a major earthquake could occur at any time.
Japan is one of the world's most earthquake-prone countries due to its location on the Ring of Fire, an arc of volcanoes and fault lines that encircles the Pacific Basin. In March 2011, Japan suffered a triple disaster when a magnitude 9 earthquake off the coast of Tohoku triggered a deadly tsunami and three meltdowns at the Fukushima Daiichi nuclear power plant.
The Japan Meteorological Agency said the Nankai Trough earthquake could be limited to the vicinity of Thursday's quake or could extend “throughout the entire Nankai Trough.”
Experts say Nankai Trough earthquakes of up to magnitude 9 could occur simultaneously or successively from Kyushu, Shikoku and parts of Honshu, such as Aichi Prefecture, to areas eastward closer to Tokyo, such as Shizuoka Prefecture.
According to a 2012 government estimate, such a quake could trigger a tsunami of more than 30 meters, causing a total of up to 320,000 deaths and economic losses of 220 trillion yen ($1.5 trillion).
It has been more than 70 years since the region last experienced a major earthquake disaster, and experts say such an event is becoming more likely.
Kishida is due to visit the Kyushu city of Nagasaki on Friday for the annual memorial for the U.S. atomic bombing of the city in 1945. He is also due to leave for Kazakhstan later the same day for summits with Central Asian countries, as well as visits to Uzbekistan and Mongolia. It was not immediately clear whether the increased risk of a Nankai Trough earthquake would affect his plans.
He said the government would “take appropriate decisions” based on the information it was collecting.
