On April 18, 2025, at 8:19 PM, a strong earthquake struck Nagano Prefecture, registering a maximum seismic intensity of 5 lower. The Japan Meteorological Agency (JMA) reported that the earthquake's epicenter was located in the northern part of Nagano, approximately 10 kilometers deep, with a magnitude estimated at 5.0. Fortunately, there is no concern about a tsunami resulting from this seismic event.
The JMA issued an emergency earthquake alert shortly after the tremor was felt. The areas that experienced the maximum seismic intensity of 5 lower included Omachi City, Ogawa Village, and Chikuhoku Village, all situated within Nagano Prefecture. In addition, several regions in Niigata Prefecture, such as Itoigawa City, Myoko City, Joetsu City, and Tokamachi City, reported a seismic intensity of 2.
In the wake of the earthquake, the JMA provided detailed seismic intensity information for various locations. The intensity levels varied across the region, with the following notable readings:
- Seismic Intensity 5 Lower: Omachi City, Ogawa Village, Chikuhoku Village (Nagano Prefecture)
- Seismic Intensity 4: Nagano City, Nagano Ikeda Town, Matsukawa Village, Matsumoto City, Azumino City, Aoki Village, Omi Village, and Ikusaka Village (Nagano Prefecture)
- Seismic Intensity 3: Chikuma City, Sakaki Town, Yamanouchi Town, Shinano Town, Ueda City, Suwa City, Shiojiri City, Yamagata Village, Asahi Village, Tatsu-no Town, Minowa Town, Neba Village, Otaki Village, Okuwa Village, and Kiso Town (Nagano Prefecture)
- Seismic Intensity 2: Numerous towns and cities across Nagano, Gunma, Niigata, Ishikawa, Yamanashi, Gifu, Shizuoka, and Aichi Prefectures
Following the initial earthquake, another tremor was recorded at around 8:54 PM, with the JMA estimating its magnitude at 2.7. This earthquake's epicenter was also in the northern part of Nagano Prefecture, specifically at coordinates 36.5 degrees north latitude and 137.9 degrees east longitude, with a depth of about 10 kilometers. Matsukawa Village in Nagano experienced a seismic intensity of 1 during this subsequent quake.
Residents across the affected areas reported feeling strong tremors, prompting many to take precautions and stay alert for further updates. The JMA has advised the public to remain vigilant and pay attention to any future information regarding aftershocks or additional seismic activity.
The earthquake on April 18 serves as a reminder of Japan's vulnerability to seismic events, given its location within the Pacific Ring of Fire, where tectonic plate movements frequently lead to earthquakes. The country has invested heavily in earthquake preparedness and response systems, which have proven effective in minimizing damage and casualties during such events.
As the situation continues to develop, local authorities are assessing the impact of the earthquake, ensuring that emergency services are on standby to assist those in need. The JMA will continue to monitor seismic activity and provide updates to the public as necessary.
In summary, the earthquake that struck Nagano Prefecture on April 18, 2025, was significant, with a magnitude of 5.0 and a maximum seismic intensity of 5 lower. While there were no tsunami warnings, the tremors were felt widely across the region, reminding residents of the ongoing seismic risks present in Japan.
