What is a Tsunami Warning? Essential Facts After a Major Earthquake

The Earthquake That Made History

An earthquake of immense power struck off the coast of Russia on July 29, ranking among the top 10 strongest earthquakes ever recorded. This seismic event measured a staggering magnitude of 8.8. For reference, earthquakes with a magnitude of 8.0 or higher are capable of causing widespread destruction and devastation to entire communities.

The U.S. Tsunami Warning System (tsunami.gov) is continuously updating its guidance as experts analyze the situation and gather more information about the potential threat. These updates include detailed maps that highlight which areas are at risk. In the immediate aftermath of a major earthquake, tsunami assessments evolve as researchers collect data from various monitoring systems.

Understanding Tsunami Alert Levels

Each alert level issued by the U.S. Tsunami Warning System carries specific instructions for the public:

• Tsunami Warning: This indicates that a dangerous tsunami is expected or already occurring. Coastal flooding and powerful currents could persist for hours or even days. It is crucial to follow local officials’ directions and consider evacuation to high ground or inland areas.

• Tsunami Advisory: A tsunami with strong currents or waves that pose a danger to those near the water is expected. Beaches and harbors may experience flooding. It’s important to stay away from the water and follow local guidelines.

• Tsunami Watch: This alert signals that a distant earthquake has occurred, and a tsunami is possible. Stay informed and be ready to take action if necessary.

• Tsunami Information Statement: This means there is no threat or the threat is very minimal. Most of the time, there is no risk of a destructive tsunami.

Residents living along the coast can check with their local emergency management offices for region-specific information and risks.

How NOAA Tracks Tsunamis

The National Oceanic and Atmospheric Administration (NOAA) employs a real-time tsunami monitoring system developed by the Pacific Marine Environmental Laboratory in Washington. This system uses strategically placed buoys called DART (Deep-ocean Assessment and Reporting of Tsunamis) to track tsunami activity.

When an earthquake occurs, the first data collected is seismic information. As the resulting tsunami wave moves across the ocean, it reaches the DART systems, which send measurements of sea level changes to tsunami warning centers. This data helps refine predictions and guide evacuation efforts.

Despite its critical role, the Pacific Marine Environmental Laboratory is facing potential budget cuts that could lead to its closure. Efforts are underway to develop a third-generation buoy system, but funding remains a challenge.

Where Does This Russian Earthquake Rank?

If the final review confirms the 8.8 magnitude, this earthquake would be tied for the sixth most powerful in history. It matches the strength of a 2010 earthquake in Chile and a 1906 earthquake near the coast of Ecuador. The largest earthquake ever recorded was the Valdivia Earthquake in Chile on May 22, 1960, which measured 9.5 on the Richter scale.

This story has been updated to include new information. Contributions by Dinah Voyles Pulver and Jeanine Santucci, USA TODAY.