What is a tsunami warning? What to know after huge earthquake.
Tsunami warnings are more serious than tsunami watches, according to the U.S. Tsunami Warning System.
An earthquake powerful enough to rank among the top 10 strongest earthquakes on record struck off the coast of Russia on July 29, triggering a series of tsunami warnings and watches.
The earthquake measured an incredible magnitude of 8.8. For context, the Michigan Technological University says magnitude 8.0 or greater earthquakes can cause massive damage and destroy communities.
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.
Here's what each of the alert levels mean, according to the agency:
- Tsunami Warning: Take Action—Danger! A tsunami that may cause widespread flooding is expected or occurring. Dangerous coastal flooding and powerful currents are possible and may continue for several hours or days after initial arrival. Follow instructions from local officials. Evacuation is recommended. Move to high ground or inland (away from the water).
- Tsunami Advisory: Take Action—A tsunami with potential for strong currents or waves dangerous to those in or very near the water is expected or occurring. There may be flooding of beach and harbor areas. Stay out of the water and away from beaches and waterways. Follow instructions from local officials.
- Tsunami Watch: Be Prepared—A distant earthquake has occurred. A tsunami is possible.Stay tuned for more information. Be prepared to take action if necessary.
- Tsunami Information Statement: Relax—An earthquake has occurred, but there is no threat or it was very far away and the threat has not been determined. In most cases, there is no threat of a destructive tsunami.
People who live along the coast can check information from their local emergency management offices to get information for their region and risks.
Map shows Tsunami warnings, watches
How does NOAA track tsunamis?
A real-time tsunami monitoring system created by the Pacific Marine Environmental Laboratory in Washington placed buoys at strategic locations throughout the ocean that play a critical role in tsunami forecasting, according to the National Oceanic and Atmospheric Administration. The buoys are named DART, for Deep-ocean Assessment and Reporting of Tsunamis.
When a tsunami event occurs, the first information available is the seismic information from the preceding earthquake, according to NOAA. As the tsunami wave moves across the ocean, it reaches the DART systems, which report sea level information measurements to the Tsunami Warning Centers. That buoy data is used to refine estimates of the tsunami source and to make the forecasts for watches, warnings and evacuations.
The Pacific Marine Environmental Laboratory is working on a third generation of the buoy system, but the laboratory is one of those proposed to be closed under the budget NOAA has proposed for the coming year.
Where does the Russian earthquake rank?
If the 8.8 magnitude remains after a final review, the earthquake would be tied for the 6th most powerful with an earthquake in Chile on Feb. 27, 2010 and an earthquake near the coast of Ecuador on Jan. 31, 1906. The largest earthquake in history, the Validivian Earthquake, occurred on May 22, 1960 and measured at a magnitude of 9.5 off the coast of Chile.
(This story has been updated to add new information.)
Contributing: Dinah Voyles Pulver and Jeanine Santucci, Paste BN