The aftermath of a powerful 7.5 magnitude earthquake that struck northeastern Japan has revealed a growing number of injuries, disrupting daily life across the region. Initial reports indicate at least 50 people sustained injuries. The earthquake triggered widespread disruptions to transportation networks, water supplies, and educational institutions.
Earthquake Details and Aftershock Alert
The Japan Meteorological Agency (JMA) reported that the significant earthquake occurred at 11:15 p.m. on Monday, originating off the eastern coast of Aomori Prefecture at a depth of 54 kilometers. In an unprecedented move, the agency issued an alert indicating the potential for another earthquake of similar or greater magnitude within the coming days.
This alert, specifically designed for coastal regions spanning from Hokkaido to Sanriku, follows the devastating earthquake and tsunami of March 2011. The alert encompasses 182 municipalities across seven prefectures, stretching from Hokkaido to Chiba, east of Tokyo.
Transportation Disruptions and Recovery
The earthquake caused immediate disruptions to transportation services. JR East, the primary rail operator in the region, temporarily suspended bullet train services on the Tohoku Shinkansen Line between Morioka and Shin-Aomori stations for thorough safety inspections. Services resumed around 3:40 p.m. after the inspections were completed.
Government Response and Public Safety
Prime Minister Sanae Takaichi addressed the nation, urging residents in the affected region to remain vigilant and stay informed through local government and weather agency updates over the coming week. She emphasized the importance of preparing for potential aftershocks, including securing furniture to prevent injuries.
“The government asks residents to continue social and economic activities while maintaining a readiness to evacuate immediately if any shaking is felt,” Takaichi stated.
Impact on Communities
- Injuries and Evacuations: Injuries were reported across Hokkaido, Aomori, and Iwate prefectures. Dozens of people sought refuge in evacuation centers overnight.
- Hospital Evacuation: In Mutsu, Aomori Prefecture, a hospital suffered damage, prompting the evacuation of 31 patients to nearby facilities. The Disaster Medical Assistance Team, firefighters, and the Self-Defense Forces collaborated in the evacuation effort after the hospital’s sprinkler system was compromised, leading to partial flooding.
- Water Supply Disruption: Approximately 1,360 homes in Aomori and Iwate prefectures experienced water outages due to damaged water pipes.
- School Closures: The earthquake also led to the closure of 139 public elementary, junior high, and high schools in Aomori Prefecture and 48 schools in Hokkaido.
Emergency Response and Evacuation Experiences
Defense Minister Shinjiro Koizumi confirmed that a Maritime Self-Defense Force air base and a Ground Self-Defense Force camp in Hachinohe, Aomori Prefecture, were opened to the public as evacuation centers. These facilities accommodated approximately 620 people and 270 vehicles at the peak of the evacuation.
Many residents were forced to evacuate in freezing temperatures following the earthquake, and tsunami warnings were initially issued. While the tsunami warnings were later downgraded to advisories and eventually lifted at 6:20 a.m. on Tuesday, the initial threat caused widespread concern.
In Hidaka, on the Pacific coast of Hokkaido, over 200 people sought refuge at a municipal center, using blankets and heaters to combat the cold. The temperature in the village dipped to minus 7.8 degrees Celsius on Tuesday morning.
Ikuko Hotta, a 74-year-old resident of Hidaka, stated, “As an earthquake had occurred off Russia’s Kamchatka Peninsula (in July), I was determined to evacuate as soon as there was a (tsunami) warning. An earthquake in the night is scary as it is dark.”
A 75-year-old woman in Kamaishi, Iwate Prefecture, recounted her experience: “I was about to go to bed when the earthquake struck. I was afraid of encounters with bears, and as I also have a husband who needs support and a cat, I wondered if I should evacuate.” She ultimately evacuated to higher ground in a car driven by her daughter.
Nuclear Facilities and Safety
Authorities reported no abnormalities at nuclear power plants in Hokkaido or the northeastern prefectures of Aomori, Miyagi, and Fukushima.
Tokyo Electric Power Company Holdings Inc. (TEPCO) temporarily suspended the release of treated radioactive water from the Fukushima Daiichi nuclear power plant into the sea following the tsunami warnings. The release operation resumed at around 2:30 p.m. on Tuesday.
The Nuclear Regulation Authority affirmed that “No safety issues have been detected” at the power plant operated by TEPCO.
At a nuclear fuel reprocessing plant in Rokkasho, Aomori Prefecture, a water leak occurred from a spent fuel storage pool, but the water remained contained within the building.
Seismic Activity and Alert System
The JMA initially reported the earthquake’s magnitude as 7.6 but later revised it to 7.5. The agency also warned of potential tsunami waves of up to 3 meters following the quake. The highest tsunami waves observed were 70 cm in Iwate.
The earthquake registered an upper 6 on the Japanese seismic intensity scale of 7 in parts of Aomori, indicating extreme shaking that makes it impossible to stand or move without crawling.
The earthquake occurred in an area along a trench off the coast of Hokkaido and northeastern Japan, where major quakes can be triggered as the Pacific plate subducts beneath the Honshu main island.
The “Off the Coast of Hokkaido and Sanriku Subsequent Earthquake Advisory” system, designed to issue special weather agency alerts following massive quakes along the trench, was implemented in December 2022. These alerts are issued after an earthquake in the area with a confirmed magnitude of 7.0 or greater.
The alert signifies a one-in-100 chance that an M8 quake or greater could occur within seven days. However, authorities do not call for preemptive evacuation even when such an alert is in effect. The alert system was established based on lessons learned from the 2011 earthquake, which triggered a devastating tsunami and the Fukushima nuclear disaster.
Notably, two days before the M9.0 quake that registered the maximum seismic intensity of 7 in 2011, an M7.3 temblor struck, producing a seismic intensity of lower 5 and generating tsunami waves of several dozen centimeters along the Pacific coast from Aomori to Fukushima.
