The Pacific Tsunami Warning Center has alerted residents of Russia’s Kamchatka Peninsula due to two earthquakes, with the strongest one measuring 7.4 in magnitude, occurring in the nearby sea on Sunday.

The most significant earthquake occurred 12 miles below the surface and 89 miles east of Petropavlovsk-Kamchatsky, a city home to 180,000 people, as reported by the US Geological Survey.

A few minutes earlier, a quake with a magnitude of 6.7 was recorded nearby.

The German Research Center for Geosciences (GFZ) mentioned that twin earthquakes, each over 6.5 in magnitude, struck the coast of Kamchatka in Russia’s far east early on Sunday.

It measured the quakes at 6.6 and 6.7 and the depth of both at 6 miles.

Measurements of earthquakes often vary in the first hours after they occur.

There were no immediate reports of casualties.

On Nov. 4, 1952, a magnitude 9.0 quake in Kamchatka caused damage but no reported deaths despite setting off many 30-foot waves in Hawaii.