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

An 8.8-magnitude earthquake struck off Russia’s eastern coast on late Wednesday morning, local time. The quake triggered tsunami waves across the Pacific that hit Russia, Japan, Canada and parts of the US coast.

A magnitude 8.2 earthquake caused a tsunami that killed more than 5,200 people on Dec. 30, 1703, according to NOAA data. The event occurred off the southwest Boso Peninsula, which is just south of Tokyo, Japan.