An earthquake with a magnitude of 7.1 hit southwestern Japan on Thursday and tsunami advisories were issued for the Pacific coast extending to the western part of the country, sparking concerns that a megaquake may occur in the near future.
The Japan Meteorological Agency issued an urgent advisory on the trench-type megaquake for the first time, warning the possibility of the quake happening along the Nankai Trough, stretching from off southwestern to central Japan, is relatively higher than usual.
In consideration of the advisory, Central Japan Railway Co. said it will run the Tokaido Shinkansen Line at a slower pace than usual for about one week, while suspending operations of some expresses in the western part of the nation.
The 4:43 p.m. quake occurred at a depth of around 30 kilometers off Miyazaki Prefecture and registered lower 6 on the Japanese seismic intensity scale of 7 in the city of Nichinan in the southern part of the prefecture, the weather agency said.
Shortly afterward, the agency began its first investigation into whether there is any link between the temblor and a potential Nankai Trough earthquake. The system has been in operation since 2017.
Around a dozen injuries were reported and several buildings were damaged, according to disaster management minister Yoshifumi Matsumura.
When an earthquake with a lower 6 seismic intensity happens, "It becomes difficult to remain standing. Doors may not open. Wall tiles and window glass may be damaged and fall," the agency said.
Prime Minister Fumio Kishida called on the public to "prepare to evacuate immediately if an earthquake occurs," telling reporters in Tokyo, "To avoid unnecessary confusion, please absolutely refrain from spreading so-called false information" through social media.
Tsunami advisories were issued for Kochi, Ehime, Oita, Miyazaki and Kagoshima prefectures, but the weather agency lifted them all by 10 p.m.
Tsunami with heights of around 50 centimeters and 20 cm were observed in Miyazaki and southwestern Kochi, respectively, the agency said.
No abnormalities were found at the Ikata and Sendai nuclear power plants in Ehime and Kagoshima prefectures, nor in the environmental radioactivity levels in the surrounding areas, the Nuclear Regulation Authority said.
The powerful temblor also disrupted transportation services around Miyazaki Prefecture in Kyushu, one of the country's four main islands. Some flights connecting Miyazaki airport with Osaka, as well as Tokyo's Haneda, were canceled.
Services of the Kyushu and Nishi Kyushu shinkansen bullet trains were temporarily suspended due to the quake, the operator said. A ferry from Miyazaki to Kobe in western Japan was canceled.
Japanese meatpacking firm NH Foods Ltd. briefly suspended operations at the plants of its three subsidiaries in Miyazaki Prefecture for checkups.
The agency, which initially estimated the quake's magnitude at 6.9, warned that quakes with a seismic intensity of around lower 6 could occur for about a week.
As of January, the government's Earthquake Research Committee forecasted a 70 to 80 percent likelihood that a quake with a magnitude of 8.0 to 9.0 will occur near the Nankai Trough within the next 30 years.
In 2012, the government estimated that up to 323,000 people could die in the megaquake.
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