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Seismicity in Japan

External images
Statistical map of location, size and depth of earthquakes near Japan
Zoomable map of recent earthquake activity
External image
Statistical map of location, size and depth of earthquakes near Japan

This is a list of earthquakes in Japan with either a magnitude greater than or equal to 7.0 or which caused significant damage or casualties. As indicated below, magnitude is measured on the Richter magnitude scale (ML) or the moment magnitude scale (Mw), or the surface wave magnitude scale (Ms) for very old earthquakes. The present list is not exhaustive, and reliable and precise magnitude data is scarce for earthquakes that occurred prior to the development of modern measuring instruments.

The islands of Japan are primarily the result of several large oceanic movements occurring over hundreds of millions of years from the mid-Silurian to the as a result of the subduction of the Philippine Sea Plate beneath the continental Amurian Plate and Okinawa Plate to the south, and subduction of the Pacific Plate under the Okhotsk Plate to the north.

Japan was originally attached to the eastern coast of the Eurasian continent. The subducting plates, being deeper than the Eurasian plate, pulled Japan eastward, opening the Sea of Japan around 15 million years ago. The Strait of Tartary and the Korea Strait opened much later. Today the Japanese archipelago is considered a mature island arc and is the result of several generations of subducting plates. Approximately 15,000 km of oceanic floor has passed under the Japanese area in the last 450 million years, with most being fully subducted.

Japan is situated in a volcanic zone on the Pacific Ring of Fire. Frequent low intensity earth tremors and occasional volcanic activity are felt throughout the islands. Destructive earthquakes, often resulting in tsunamis, occur several times a century.


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