At least 12 people were injured following a magnitude-6.6 earthquake that struck a wide area of western Japan the previous night, authorities said Thursday.

The quake at 11:14 p.m. Wednesday registered lower 6 on the Japanese seismic intensity scale of 7 in Ainan, Ehime Prefecture, and Sukumo, Kochi Prefecture, both on Shikoku Island, according to the Japan Meteorological Agency.

Seven people were slightly injured in Ehime, while in Sukumo two women in their 70s suffered serious injuries, including broken bones, and a man in his 40s suffered minor injuries, according to prefectural governments and local fire departments. Two were also hurt in Oita Prefecture in the Kyushu region, southwestern Japan.

Shikoku Railway Co. suspended some services on its lines from the start of Thursday but is expected to fully resume operations Friday.

A police officer cleans up debris in Uwajima in Ehime Prefecture, western Japan, on the morning of April 18, 2024, after an earthquake with a magnitude of 6.6 hit Ehime and Kochi prefectures the previous night. (Kyodo) ==Kyodo

"We have avoided the worst situation," Kochi Gov. Seiji Hamada said, citing the low number of human casualties and the progress of recovery efforts.

A valve defect reduced the power output of the No. 3 reactor at the Ikata nuclear complex in Ehime Prefecture by 2 percent, though there was no major problem with overall operations, Shikoku Electric Power said.

In Sukumo, 23 people evacuated temporarily, while water supplies in the city were disrupted due to burst pipes at many locations. Ten residents in Yusuhara, Kochi Prefecture, were also temporarily cut off due to fallen trees.

Photo shows a partially collapsed stone wall in Ainan in Ehime Prefecture, western Japan, on April 18, 2024, after an earthquake with a magnitude of 6.6 hit a wide area of western Japan the previous night. (Kyodo) ==Kyodo

The focus of the quake in the Bungo Channel was in a zone that a government panel has said could see a devastating temblor with a magnitude of at least 8.0 in the next 30 years.

However, an agency official told a press conference it was unlikely that the latest temblor had increased the chances of a massive quake.

The temblor occurred in the Philippine Sea Plate, which has a different seismic mechanism than a potential Nankai Trough quake, the agency said. Its epicenter was also located around 10 kilometers deeper than the plate boundary for a massive earthquake, the agency added.

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