Sagami Sea Valley
October 18, 2021
The Sagami trough (Japanese: 相模 (Sagami) traf [*], English: Sagami Trough) is a 340 km long gorge extending southeast of Sagami Bay off the coast of Tokyo, Japan. This is the convergence boundary where the Philippine Sea Plate sinks under the Okhotsk Plate. It reaches the Japan Trench at the southeast end, and meets the Nankai Trench at Sagami Bay to the west. Passing through the northern part of the Izu Islands. It is the cause of the major earthquakes that occur regularly every 200 years (the Kenroku earthquake of 1703, the Ansei Edo earthquake of 1855, and the Great Kanto earthquake of 1923). Earthquakes greater than 7 on the Richter scale and earthquakes greater than 8 occur alternately every 100 years.