Multiple independent sources (Dailydispatch, two web search results) report that an earthquake with a preliminary magnitude of 5 struck the Nagano prefecture in central Japan on Saturday, citing NHK or the weather agency. One web search result contradicts the day (stating Friday) and magnitude (5.1 vs 5), but the core elements (M5, Nagano, Saturday/central Japan, NHK reporting) are consistently reported across multiple sources.

Multiple sources corroborate the details regarding the location (Omachi, northern Nagano), the approximate time (around 1:20 PM), and the reporting body (NHK/Japan Meteorological Agency). While the exact time/date varies across the search results, the core elements are consistently reported by independent web sources.

Multiple independent sources (Dailydispatch and two web search results) report that the earthquake registered a seismic intensity of upper-5 on Japan's 1-7 scale, along with the description that it was strong enough to make movement difficult without support.

Multiple independent sources confirm that Japan is highly seismically active. One source notes that four tectonic plates converge on Japan, and another states it is one of the most earthquake-prone countries on Earth, supported by the general context of the web search results.

Two distinct web search results (The Jerusalem Post and The Straits Times) independently report the statistic that Japan accounts for about one-fifth of the world's earthquakes of magnitude 6 or greater. This meets the requirement for corroboration from multiple independent sources.