Twenty seconds. That’s how long Daiki Shimohata held his two children as the earth convulsed beneath his Aomori home at 11:15 p.m. Monday. “The tremor was something we’ve never experienced,” he said. “It reminded me of 2011.”
For 90,000 residents, that memory wasn’t nostalgia—it was trauma resurfacing. The magnitude 7.5 earthquake had just awakened Japan’s deepest fear: Is this the Big One?
A Magnitude 7.5 Message from the Deep
At 11:15 p.m. Monday, December 8, a magnitude 7.5 earthquake ruptured the seafloor 80 kilometers off Aomori Prefecture, 54 kilometers beneath the surface. The Japan Meteorological Agency initially reported 7.6, then revised downward.
Upper-6 intensity shaking meant residents couldn’t stand or move without crawling. For those asleep, it was a violent awakening. For those awake, it was primal uncertainty: would the building hold?
Sirens in the Night
Within moments, tsunami warnings blared across Hokkaido, Aomori, and Iwate prefectures. The Japan Meteorological Agency warned of waves potentially reaching three meters—enough to flood cities, destroy everything in its path. People had minutes to reach high ground or face drowning.
The psychology of a tsunami warning in Japan isn’t weather forecasting; it’s reckoning. Sirens wailed. Residents didn’t debate. They ran.
90,000 People Into Darkness
Approximately 90,000 residents evacuated across three prefectures in the first hours. Some grabbed children. Others abandoned homes entirely. Many had no clear sense of when they’d return.
Around 480 evacuees converged on Hachinohe Air Base, where helicopters waited and military personnel offered protection. Others crowded into school gymnasiums and community centers.
Racing Against the Waves
The Pacific Tsunami Warning Center issued alerts for coasts up to 1,000 kilometers away, warning of potentially hazardous waves that could reach Russia and beyond. The Shinkansen bullet train service was suspended between Fukushima and Aomori. Local rail lines halted.
About 200 passengers stranded overnight at New Chitose Airport were unable to leave and had no idea if their homes were still standing. The infrastructure that normally moves millions became a bottleneck when seconds mattered most.
The Waves Arrive—But Not as Feared
By early Tuesday morning, tsunami waves hit Japan’s northeastern coast measuring approximately 70 centimeters—a fraction of the three-meter nightmare authorities had warned about. Ports recorded the waves. Coastal sensors tracked movement. The danger was real, but manageable.
By early Tuesday, the Japan Meteorological Agency downgraded the warning to advisory, then lifted it entirely. Relief washed over residents: evacuation had worked. Protocols had held.
The Invisible Threat Still Waiting
As residents were told it was safe to return, authorities issued an unsettling warning: a megaquake advisory for at least one week, signaling a stronger earthquake could occur within days. This wasn’t speculation. After a major quake, the probability of additional large earthquakes in the affected region increases temporarily.
According to a representative from the Japan Meteorological Agency, “There is a possibility that further powerful and stronger earthquakes could occur over the next several days.”
Injuries and Infrastructure Damage
At least 30 people were injured across the region, with one sustaining serious injuries. Most injuries came from falling objects—furniture tumbling from shelves, fixtures coming loose. A fire broke out in at least one residential area.
Approximately 2,700 homes in Aomori Prefecture lost power in the frigid December night, leaving families without heat or light. Remarkably small for a magnitude 7.5 earthquake—testament to Japan’s building codes—yet for families affected, it was devastating.
Prime Minister Calls Emergency Response
Within minutes, Prime Minister Sanae Takaichi convened an emergency response team at the Prime Minister’s Office Crisis Management Center. In a statement released to the nation, she emphasized: “With the priority of preserving human life, the government will unite in its efforts to fully commit to emergency disaster response initiatives.”
She called for furniture to be secured and residents to prepare for immediate evacuation if shaking resumed during the coming week.
Helicopters and Military Mobilization
Defense Minister Shinjiro Koizumi deployed 18 defense helicopters for damage assessment and rescue operations as dawn broke Tuesday. The military mobilization underscored the government’s seriousness about both the immediate aftermath and the broader threat.
These helicopters represented Japan’s institutional memory of disaster. Every government agency has rehearsed its protocols since 2011. Yet each earthquake is unique, testing those protocols again in real time.
The Nuclear Question
As sirens still echoed across the region, authorities turned attention to nuclear facilities. Chief Cabinet Secretary Minoru Kihara stated: “There were no irregularities reported at Higashidori, Onagawa, or the disabled Fukushima nuclear power plants.”
However, the Rokkasho reprocessing plant reported a minor radioactive water spillage, which was quickly contained. For residents who endured the 2011 explosions and meltdowns at Fukushima Daiichi, such statements land differently: believed, but with caution.
Rail Networks Suspended Across Northeast
The East Japan Railway Company suspended Shinkansen bullet train services between Fukushima and Aomori, halting the vital connection between the region’s economy and transportation. Multiple local rail lines also suspended or severely delayed as operators inspected tracks, bridges, and infrastructure.
For a nation moving millions daily on rail, these suspensions meant more than inconvenience: economic disruption, stranded commuters, and faltered supply chains.
The Memory of 2011 Never Fades
Daiki Shimohata’s instinct to compare Monday’s earthquake to 2011 wasn’t unique—it was universal across the region. On March 11, 2011, a magnitude 9.0 earthquake triggered a tsunami killing more than 18,000 people, wiping entire towns off the map. Confirmed deaths reached 15,889, with 2,601 additional missing.
The tsunami crippled Fukushima Daiichi, causing explosions and meltdowns, contaminating large areas and displacing hundreds of thousands. For regional residents, that disaster isn’t history; it’s a wound unhealed.
The Nankai Trough
To understand the context, look beyond Monday to the Nankai Trough, a deep ocean trench running along Japan’s Pacific coast. According to Japan’s Earthquake Research Committee, the probability of a magnitude 8 to 9 earthquake along the trough within 30 years stands at 60 to 90 percent or higher.
The last confirmed megaquake occurred in 1946 at a magnitude of 8.0. With each passing year, the probability of being overdue increases.
A Nation’s Worst Nightmare
Japanese government estimates for a worst-case Nankai megaquake paint a grim picture: a magnitude 9 could kill approximately 298,000 people and inflict economic losses of roughly $2 trillion USD. Tsunamis 30 meters high could stretch across Japan’s Pacific coastline from Hokkaido to Chiba and beyond.
Entire cities are inundated. Critical infrastructure destroyed. Japan’s third-largest economy disrupted globally. Monday wasn’t that event. But it reminded the nation that such an event remains inevitable.
The Week of Vigilant Waiting
As of Tuesday morning, residents across Hokkaido, Aomori, and Iwate were in heightened alert. Schools prepared contingency closures. Employers considered flexible arrangements. Families checked their emergency kits, which included water, food, first aid supplies, battery-powered radios, and flashlights.
Social media is filled with photos of secured furniture, stocked emergency shelves, and evacuation route maps. Yet life continued: people worked, stores remained open, and children attended classes. Japan had learned to balance preparedness with living, acknowledging risk seriously without allowing paralysis.
Sources:
Japan Meteorological Agency, news reports via Reuters, CNN, Strait Times, Sky News, Al Jazeera, France24, Channel NewsAsia, Japan Times, Independent UK (December 8-9, 2025)
Prime Minister Sanae Takaichi official statements, Defense Minister Shinjiro Koizumi announcements, Chief Cabinet Secretary Minoru Kihara briefings
National Police Agency / NCBI research on 2011 Great East Japan Earthquake and Tsunami mortality data