The 8.8 magnitude quake off Russia that triggered tsunami warnings across the Pacific occurred on what is known as a "megathrust fault", where the denser Pacific Plate is sliding underneath the lighter North American Plate.

Russia's massive quake has already triggered at least 10 aftershocks, and could continue for months, according to scientists.

A powerful 8.7 magnitude earthquake struck off Russia’s Kamchatka Peninsula on Wednesday, triggering tsunami warnings in Russia, Japan, and across the Pacific including the US west coast, Hawaii and Micronesian islands.