MENLO PARK (CBS SF) — The United States Geological Survey reports a 6.6 magnitude earthquake occurred Sunday at 11:32 a.m. PDT, off the coast of Russia’s Kuril Islands, about 780 miles northeast of Tokyo.

A tsunami warning was not immediately issued.

The Kuril-Kamchatka arc extends approximately 2,100 km from Hokkaido, Japan, along the Kuril Islands and the Pacific coast of the Kamchatka Peninsula to its intersection with the Aleutian arc near the Commander Islands, Russia.

It marks the region where the Pacific plate subducts into the mantle beneath the Okhotsk microplate, part of the larger North America plate.