TOKYO - A powerful earthquake with a magnitude of 7.1 shook southwestern Japan on Thursday afternoon but no major damage was reported and only relatively minor tsunami waves reached the coast.
The quake occurred at 4.43pm local time at a depth of around 30 kilometres off Miyazaki prefecture. It registered in the lower 6 range on the Japanese seismic intensity scale of 7 in the city of Nichinan in the southern part of the prefecture, the Japan Meteorological Agency said. The magnitude was revised down from 6.9.
Tsunami advisories were issued for Kochi, Miyazaki and other prefectures.
Around a dozen injuries were reported and several buildings were damaged, according to disaster management minister Yoshifumi Matsumura.
No disruptions to infrastructure, including electricity, water and telecommunications, were reported.
No abnormalities were found at the Ikata and Sendai nuclear power plants in Ehime and Kagoshima prefectures, their operators said.
Services on the Kyushu and Nishi Kyushu shinkansen bullet trains were temporarily suspended due to the quake, the operator said.
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 weather agency said.
It said it has started investigating whether there is a link between the temblor and a potential massive trench-type “megaquake” along the Nankai Trough off western and central Japan.
The agency warned that quakes with a seismic intensity of around lower 6 could happen for about a week.
The government’s Earthquake Research Committee in January this year forecast a likelihood of 70-80% that a quake with a magnitude of 8.0 to 9.0 would occur near the Nankai Trough within the next 30 years.
In 2012, the government estimated that up to 323,000 people could die in a megaquake of that magnitude.
Prime Minister Fumio Kishida called on the public to reaffirm their preparedness for any further quakes and be ready to evacuate quickly once a jolt comes.
In the worst-case scenario, a powerful temblor could shake a wide area of Japan — from the Kanto region centred on Tokyo to the southwestern Kyushu region — and high tsunami waves could engulf the coastal areas of Kanto to Okinawa, according to the Japan Meteorological Agency.
Naoshi Hirata, the head of an advisory body to the weather agency that assessed the latest quake, said the probability of a major earthquake along the Nankai Trough has now increased “several times”.