Photo/Illutration Shigeki Aoki, an official with the Japan Meteorological Agency, speaks at a news conference in Tokyo after an earthquake struck off the coast of Miyazaki Prefecture on the night of Jan. 13. (Takeshi Komiya)

The Japan Meteorological Agency urged Kyushu residents to be wary of aftershocks from the strong Jan. 13 earthquake but said the temblor did not heighten the risk of a dreaded Nankai Trough megaquake.

Aftershocks with a maximum seismic intensity of lower 5 on the Japanese scale of 7 could strike the area over the next seven days, the agency said.

The Jan. 13 earthquake, centered in the Hyuganada Sea off the coast of Miyazaki Prefecture, occurred at 9:19 p.m. with its focus about 30 kilometers deep.

It had a maximum intensity of lower 5.

The agency also issued a statement that said the likelihood of a Nankai Trough earthquake remained the same as in normal times.

The Nankai Trough, the border area between the Eurasian Plate and the Philippine Sea Plate, runs from the Tokai to Kyushu regions off the Pacific coast.

According to the JMA, there is a 70- to 80-percent possibility that a megaquake emanating in the Nankai Trough area will occur within 30 years.

The agency held a meeting of experts to evaluate whether the Jan. 13 earthquake could lead to seismic activity in the Nankai Trough.

The quake had a preliminary estimated magnitude of 6.9, but upon closer look, the JMA revised it down to 6.7. That level falls under the criteria of magnitude 7.0 or greater for the JMA to issue a warning of a Nankai Trough earthquake.

In 2024, the JMA issued its first megaquake advisory, covering 707 municipalities from Okinawa to Ibaraki prefectures, after a magnitude-7.1 earthquake struck off Miyazaki Prefecture in the Hyuganada Sea on Aug. 8.

That quake had a maximum intensity of lower 6.

The Jan. 13 earthquake had an intensity of lower 5 in the towns of Takanabe and Shintomi and Miyazaki city in Miyazaki Prefecture.

A tsunami warning was issued for coastal areas of the prefecture and Kochi Prefecture. The tsunami reached the port of Miyazaki at 9:36 p.m.

Shortly after 10 p.m., a 20-centimeter tsunami was observed at the port and the coast in Nichinan, also in Miyazaki Prefecture.

No serious injuries or fatalities were reported.