Japan’s northern Pacific coast has endured a harrowing week, rattled by a series of powerful earthquakes and tsunami advisories that have left residents on edge and authorities urging continued vigilance. On the morning of December 12, 2025, a magnitude 6.9 earthquake struck off the coast of Aomori Prefecture at 11:44am local time, the latest in a string of tremors that have tested the nation’s famed disaster preparedness and stoked memories of past tragedies.
The Japan Meteorological Agency (JMA) initially measured Friday’s quake at magnitude 6.7, later revising it to 6.9. The epicenter lay 20 kilometers beneath the sea, not far from where a much larger magnitude 7.5 earthquake had hit just three days earlier, on December 9. That earlier tremor was particularly destructive, injuring at least 51 people, tearing apart roads, shattering windows, and triggering tsunami waves of up to 70 centimeters. Tens of thousands of residents were ordered to evacuate to higher ground, and temporary shelters sprang up across Aomori and Hokkaido to provide warmth and safety in freezing winter conditions.
When the December 12 quake struck, the JMA quickly issued a tsunami advisory, warning of possible one-meter waves along the Pacific coasts of Hokkaido, Aomori, Iwate, and Miyagi prefectures. Within an hour, two 20-centimeter tsunami waves were observed—one at 12:35pm in Erimo town on Hokkaido, and another three minutes later in the Aomori region. Fortunately, according to broadcaster NHK, there was no significant change at either port, and the advisory was lifted about two hours later. Still, some communities along the coast were evacuated as a precaution, a sign of just how seriously these warnings are taken in a country shaped by seismic risk.
Japan’s Nuclear Regulation Authority moved swiftly to reassure the public, reporting no immediate signs of abnormalities at nuclear facilities in the affected region. Tohoku Electric Power Company confirmed that the Higashidori nuclear power plant in Aomori and the Onagawa plant in Miyagi were operating normally, and Tokyo Electric Power Company stated that radiation levels at the Fukushima Daiichi and Daini plants remained stable. These reassurances are vital in a country still haunted by the 2011 Tohoku disaster, when a magnitude 9.0 earthquake and resulting tsunami led to catastrophic failures at the Fukushima Daiichi nuclear plant and left about 18,500 people dead or missing.
The JMA’s response to this week’s seismic activity has been swift and unprecedented. Following Monday’s magnitude 7.5 quake, the agency issued its highest-level warning—a rare special advisory—cautioning residents across a vast area, from Hokkaido in the north to Chiba, east of Tokyo, that the risk of a powerful aftershock or even a megaquake (magnitude 8 or higher) remained elevated for at least a week. This top-tier alert, which will stay in effect until December 16, marks the first time such a warning has been issued since the system was introduced in 2022.
Experts say the region’s seismic zone is historically active, with major earthquakes tending to occur in sequence. Fumiaki Tomita, associate professor at Tohoku University’s International Research Institute of Disaster Science, warned, “Earthquakes with magnitudes of 8 could strike the area if large-scale slips occur between the two plates.” He cautioned that the northern area off Iwate is now the only segment of this offshore fault system that has not released a large earthquake since 1968, and unruptured segments can accumulate strain, making them more likely to produce powerful quakes and tsunamis.
Adding to the anxiety, Friday’s 6.9-magnitude event was followed by a magnitude 5.7 aftershock at 12:21pm and several smaller tremors, according to the Japanese weather agency and the United States Geological Survey. The NERV disaster prevention app reported that shaking from these quakes reached intensity 4 on Japan’s seven-tier seismic scale in several prefectures, including Ibaraki, Tochigi, Saitama, and Chiba. Milder shaking was also felt in parts of Fukushima, Gunma, and other regions.
The government’s megaquake advisory has prompted a surge in demand for disaster supplies. According to NHK, sales of bottled water, disaster kits, torches, and support poles to prevent furniture from toppling have tripled in some stores. One man in his 30s told NHK, “We decided to prepare, so I bought disaster kits for everyone.” In Hokkaido’s Hakodate city, shelves of emergency gear have become a common sight, as families brace for the possibility of more severe shaking or tsunami waves.
Japan’s vulnerability to earthquakes is rooted in its geography. The archipelago sits at the intersection of four major tectonic plates along the so-called Pacific “Ring of Fire,” making it one of the world’s most seismically active countries. The Japan Trench and the Chishima Trench, both deep oceanic cracks where one plate slides beneath another, are notorious for producing powerful megathrust earthquakes. The government has warned that a megaquake along the Nankai Trough—another undersea trench south of Honshu—could kill as many as 298,000 people and cause up to $2 trillion in damage.
Historical patterns show that magnitude-7 or higher quakes in these regions can be followed by even larger earthquakes, which is why the JMA’s megaquake advisory system was established. The agency’s projections suggest that if a particularly large trench earthquake were to strike, tsunami waves could reach 10–30 meters in some areas, with towns like Erimo and Hachinohe facing especially dire risks. The strongest shaking would likely be felt in Hokkaido and northern Honshu, with the potential to disrupt infrastructure, transportation, and daily life on a massive scale.
For now, the quick response of authorities and the good fortune of low tide have helped minimize the impact of this week’s tsunamis. Shunichi Koshimura, a professor at Tohoku University’s International Research Institute of Disaster Science, explained to local media that “it was lucky that the highest tsunami in the Monday quake came at low tide, which means that the tide level is 1.5 metres lower than at high tide.” If the same wave had hit at high tide, the risk of flooding and damage would have been much greater.
As aftershocks continue to rattle the region and the megaquake advisory remains in place, residents of northern Japan are taking no chances. Schools have closed in some areas, evacuation routes are being reviewed, and families are assembling emergency kits. The memory of 2011 looms large, but so does the determination to be ready for whatever comes next. In a country where earthquakes are a fact of life, preparedness is both a necessity and a way of life.
