A series of strong earthquakes struck Nagano Prefecture on April 18, 2026, prompting urgent warnings from the Japan Meteorological Agency (JMA) for residents to remain vigilant for at least one week. Foreign residents throughout central Japan should understand the ongoing risks and take appropriate precautions. According to NHK, the initial earthquake occurred at approximately 1:00 PM, registering magnitude 5.0 with its epicenter in northern Nagano Prefecture. The city of Omachi experienced the strongest shaking at intensity 5+ (5-strong) on Japan's seismic scale, which measures ground motion effects rather than magnitude. This level of shaking can cause unsecured furniture to topple and make standing difficult. The seismic activity did not stop with the first quake. Just two hours later, at around 3:00 PM, another significant earthquake struck the same region, this time registering intensity 5- (5-weak) in Omachi. Professor Shinichi Sakai from the University of Tokyo's Earthquake Research Institute told NHK that the afternoon earthquake appeared similar in scale to the earlier one, indicating ongoing seismic activity in the fault zone. The JMA held a press conference at 3:20 PM on April 18 to address public concerns and provide guidance. Officials emphasized that residents should expect similar-scale earthquakes to continue for approximately one week following the initial event. This warning is based on historical patterns observed in the region, where earthquakes of comparable magnitude have occurred in clusters. For foreign residents unfamiliar with Japan's seismic intensity scale, it's important to understand that intensity 5+ represents significant shaking. At this level, many people find it difficult to move freely, dishes and books may fall from shelves, and unsecured furniture can shift or topple. While modern buildings in Japan are designed to withstand such tremors, older structures may sustain damage. NHK reported on the immediate impacts and transportation disruptions caused by the earthquakes, though specific details about casualties or major structural damage were not included in initial reports. The focus of authorities has been on ensuring residents remain prepared for potential aftershocks and additional seismic events. Experts stress that the one-week warning period is particularly critical. Professor Sakai explained that the geological conditions in northern Nagano suggest the possibility of continued earthquakes of similar magnitude. This doesn't mean larger earthquakes are impossible, but rather that residents should maintain heightened awareness and preparedness. For expats living in Nagano Prefecture or surrounding areas, now is the time to review emergency procedures. Ensure your emergency kit is accessible and contains essentials like water, non-perishable food, flashlights, batteries, and any necessary medications. Keep important documents and identification in a readily accessible location. Familiarize yourself with evacuation routes and designated emergency shelters in your area. Many municipalities provide multilingual disaster information through their websites and apps. If you haven't already, download the Japan Meteorological Agency's earthquake early warning app and ensure your phone's emergency alert system is activated. Secure heavy furniture, appliances, and wall-mounted items that could fall during strong shaking. Place heavy objects on lower shelves and ensure exit routes from your home remain clear of obstacles. If you feel strong shaking, immediately take cover under a sturdy desk or table, protect your head, and stay away from windows. The northern Nagano region has experienced similar seismic clusters in the past, making this week's activity part of a known geological pattern. However, earthquakes remain inherently unpredictable, and preparedness is essential for all residents, regardless of how long they've lived in Japan. Stay informed through official channels like NHK World for English-language updates, and follow guidance from local authorities. The one-week caution period is not meant to cause panic but to ensure residents remain alert and prepared for potential continued seismic activity in the region.