Japan Trench

The Japan Trench is a deep ocean trench east of northern Honshu where the Pacific Plate descends beneath the Okhotsk microplate, part of the North American Plate system.

Japan Trench megathrust: The shallow plate-boundary fault along which the Pacific Plate thrusts beneath the overriding plate near Japan. This fault produced the 2011 Tōhoku earthquake and tsunami.
Pacific Plate: A major oceanic tectonic plate underlying much of the Pacific Ocean basin. Its westward motion carries oceanic crust into the Japan Trench.
2011 Tōhoku earthquake: The magnitude 9.0–9.1 earthquake that ruptured the Japan Trench plate boundary on March 11, 2011. It demonstrated that shallow trench sediments can participate in giant ruptures.
Seismic coupling: The degree to which motion across a plate boundary is locked and accumulates elastic strain between earthquakes. Its along-trench variation affects where future large ruptures may occur.
Subduction: The process in which one tectonic plate sinks beneath another into the mantle. The trench marks the surface expression of Pacific Plate subduction.
Okhotsk Plate: A tectonic microplate covering the Sea of Okhotsk and parts of northern Japan and eastern Russia. It is commonly treated as the overriding plate at the northern Japan Trench.
1896 Sanriku earthquake: A magnitude 8.0–8.5 earthquake off Sanriku, Japan, that generated a devastating tsunami in 1896. Its unusually large tsunami relative to shaking exemplifies a tsunami earthquake near the trench.
Slow slip event: A gradual fault slip episode lasting days to years that releases strain without strong seismic waves. Detecting slow slip helps assess how strain is transferred toward the megathrust.
Megathrust earthquake: A large earthquake caused by sudden slip on a fault at a subduction-zone plate boundary. The plate interface beneath the trench can rupture in unusually large earthquakes.
North American Plate: A major tectonic plate that includes North America and parts of the western North Atlantic and Arctic seafloor. Some plate models place the Okhotsk microplate within this broader plate system.

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