Nankai Trough

Current Context : Japan issues its first-ever ‘megaquake advisory of strong shaking and large tsunaml on the Nankai Trough.

• After a1-magnitude earthquake shook southern Japan on Thursday (August 8), the country’s meteorological agency issued its first-ever “megaquake advisory”.

ABOUT NANKAI TROUGH :

• It is an underwater subduction zone (nearly 900 km long) where the Eurasian Plate collides with the Philippine Sea Plate, pushing the latter under the former and into the Earth’s mantle.
• This accumulates tectonic stress which can cause a megaquake — an earthquake with a magnitude larger than 8.
• It is located off the southeastern coast of Japan, in the western Pacific Ocean.
• It extends from the Izu-Bonin Arc in the south to the Tokai region in the north, running parallel to Japan’s southern coast.
• This region is crucial in the study of tectonics, earthquakes, and tsunami generation.
• The trough has produced large earthquakes roughly every 100 to 150 years.