Tōnankai earthquakes


The Tōnankai earthquakes are major megathrust earthquakes that affect the Tōnankai region of Japan, between the Tōkai region and Nankaidō region, and are caused by ruptures in the Tōnankai zone of the Nankai megathrust, specifically segments C and/or D.
These are a class of Nankai megathrust earthquakes, frequently occurring in combination with a rupture of segment E, and either in combination with or followed by a rupture of segment A and/or B.
The most notable Tōnankai earthquake, and the only earthquake known to have consisted of ruptures in the Tōnankai zone only, is the 1944 Tōnankai earthquake.

History

The distinction of Tōnankai earthquakes, and the Tōnankai region itself, is a recent one, dating to the 1944 Tōnankai earthquake. Nankai and Nankaidō, and likewise Tōkai and Tōkaidō are historical names and divisions of Japan, but following the 1944 earthquake, it was recognized that there were distinct segments in between these, which could independently rupture, and thus a different category was created.