A magnitude 5 earthquake (最大震度5弱の地震) hit northern Nagano Prefecture on Friday evening at 8:19 p.m.
According to JapanNews, the tremor registered as lower 5 on the Japanese seismic scale of 7 in Omachi City and Ogawa village. No tsunami warnings have been issued following the quake.
Japan experiences approximately 1,500 earthquakes (日本の地震)each year, making it one of the most seismically active regions in the world. This geological reality has profoundly shaped Japanese culture, architecture, and disaster preparedness.
Japan sits along the Pacific Ring of Fire, where several tectonic plates converge. The country lies at the junction of four major plates: the Pacific, Philippine Sea, Eurasian, and North American plates. As these plates interact, they create tremendous pressure that periodically releases in the form of earthquakes.
The subduction of the Pacific Plate beneath the Okhotsk Plate (part of the North American Plate) is particularly significant, as it forms the Japan Trench east of Honshu and has been responsible for many of Japan’s most devastating earthquakes.
Throughout history, major earthquakes have repeatedly altered Japan’s landscape and society:
- The 1923 Great Kanto Earthquake devastated Tokyo and Yokohama, killing over 140,000 people and leading to significant urban planning changes.
- The 1995 Great Hanshin (Kobe) Earthquake killed approximately 6,400 people and exposed weaknesses in Japan’s disaster response systems.
- The 2011 Tohoku Earthquake, measuring magnitude 9.0, triggered a devastating tsunami and the Fukushima nuclear disaster, claiming nearly 20,000 lives.
Japan uses its own seismic intensity scale that measures the degree of shaking at a specific location, unlike the Moment Magnitude Scale (formerly Richter scale) that measures the energy released at the earthquake’s source.
The Japan Meteorological Agency (JMA) scale ranges from 1 (barely perceptible) to 7 (extreme destruction), with levels 5 and 6 further divided into “lower” and “upper” categories. This scale helps communicate the localized impact of earthquakes to residents.
