Thanks to this global monitoring system, which has been deployed for more than 20 years, millions of people in Japan and Russia were warned.

After an 8.8-magnitude earthquake off the coast of Russia’s Kamchatka peninsula, early tsunami warning systems kicked in and helped millions of people safely evacuate

The U.S. Tsunami Warning System ( tsunami.gov) will be updating its guidance as experts learn more about the threat, including maps showing what areas face what risks. In the minutes and hours after a major earthquake, tsunami assessments change as researchers track data from buoy and other interments.