What is the name of the subduction zone off the coast of Tohoku, Japan?

The subduction zone off the coast of Tohoku, Japan, is called the Japan Trench. It marks the boundary where the oceanic Pacific Plate descends beneath the Okhotsk microplate, which includes northeastern Japan.

This deep ocean trench runs broadly along Japan’s northeastern Pacific coast, from near Chiba toward Hokkaido. As the Pacific Plate moves west-northwestward, friction and bending at the plate boundary generate frequent earthquakes, including powerful megathrust events.

The Japan Trench is closely associated with the 2011 Tōhoku earthquake and tsunami. That magnitude 9.0–9.1 earthquake ruptured a large section of the plate boundary and produced devastating waves along Japan’s northeastern coast. The trench itself is therefore both a geographic feature and part of an active earthquake-generating subduction system.

A common mix-up is the Nankai Trough, another Japanese subduction zone farther southwest. The Kuril Trench lies north of the Japan Trench near Hokkaido and the Kuril Islands, while the Mariana Trench is in the western Pacific near the Mariana Islands.