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

The quake off the waters off the coast of Russia's Kamchatka peninsula was also among the world's 10 largest earthquakes since 1900.

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.