On April 18, 2025, at around 8:19 PM, an earthquake registering a seismic intensity of 5 lower struck the northern and central regions of Nagano Prefecture, Japan. The Japan Meteorological Agency reported that the earthquake had a magnitude of approximately 5.0, with its hypocenter located about 10 kilometers deep. Fortunately, there is no tsunami threat associated with this seismic event.
The areas most affected by the quake included Omachi City, Chikuhoku Village, and Ogawa Village, where the seismic intensity was recorded at 5 lower. Nearby cities such as Nagano and Matsumoto experienced a slightly weaker tremor, registering at a seismic intensity of 4. Tremors were felt across a broader region, extending from Kanto-Koshinetsu to Hokuriku and Tokai, where intensities ranged from 3 to 1.
According to officials from Omachi City, there were no significant damages reported within city hall following the quake. A representative from the Crisis Management Division stated, "No major damage has been confirmed inside the city hall." In response to the earthquake, Nagano Prefecture has convened an emergency alert meeting led by the Director of the Crisis Management Department to monitor the situation closely.
Despite the lack of major damage reports, some areas in Ogawa Village experienced power outages, as confirmed by local officials. By around 8:55 PM, they noted that while there were no reports of injuries, certain regions within the village were without electricity.
Transportation services were also impacted by the quake. The Hokuriku Shinkansen line reported delays on its down line between Toyama Station and Takasaki Station, beginning at around 8:45 PM. Additionally, safety inspections were initiated on highways in the area, leading to speed restrictions of 50 kilometers per hour on specific stretches of the Joshin-etsu Expressway and the Nagano Expressway.
Experts have weighed in on the seismic activity in the region. Professor Shinji Toda from the University of Tokyo, who specializes in earthquake studies, indicated that northern Nagano Prefecture is a relatively active seismic zone, with earthquakes of magnitude 5 occurring approximately every few years. He noted, "The hypocenter is shallow, so there is a possibility that the shaking was felt locally strongly, and there is a risk of landslides and rupture of water pipes."
This recent earthquake marks a significant event for Nagano, as it is the first time a seismic intensity of 5 lower has been recorded since the Noto Peninsula earthquake on New Year's Day of 2024. The last major earthquake to hit the northern part of Nagano Prefecture occurred on May 25, 2018, when a magnitude 5.2 quake resulted in a maximum intensity of 5 upper.
Officials from various municipalities reported on the experience of the tremors. In Omachi City, city hall staff described the shaking as a large horizontal movement lasting several tens of seconds, but noted that no items fell from shelves. Similarly, officials from Chikuhoku Village reported a sudden and strong upward shaking but confirmed that nothing fell from the shelves there either. In Ogawa Village, local officials described a vertical shaking that lasted a few seconds, with no damage reported and essential services like water and electricity remaining operational.
At the NHK Nagano Broadcasting Station, which is located in Nagano City, staff reported experiencing a smaller horizontal shaking while in the basement, which lasted for several seconds.
As the region continues to assess the aftermath of the earthquake, local authorities remain vigilant. The public has been advised to stay alert for any aftershocks and to report any damages or incidents promptly. Emergency services are on standby to respond to any arising needs as the situation unfolds.
In summary, while the earthquake caused considerable tremors across Nagano Prefecture, the immediate response from local authorities and emergency services has been swift. The absence of serious damage or injuries is a relief to residents, and ongoing assessments will ensure that any potential risks are managed effectively.
