Russia’s magnitude 8.8 earthquake spawned serious tsunami warnings, but waves have been moderate so far. Here’s the geological reason why

Eyewitness video captured tsunami waves flooding the small Russian town of Severo-Kurilsk on Wednesday morning.

Millions of people were evacuated, as minds cast back to the devastating tsunami of Boxing Day 2004 in the Indian Ocean and Japan 2011, both triggered by similarly large earthquakes. But today's tsunami has been much less severe, even though it's brought some damage.