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Emergency Preparedness and Response

Tsunamis

Tsunamis are large, powerful waves usually triggered by sudden movements in the seafloor, most commonly from underwater earthquakes, but they can also result from volcanic eruptions, landslides, certain types of weather, and meteorites. One of these events causes the displacement of large volumes of water. These series of waves, often referred to as wave trains, can persist for hours. These waves travel at high speeds across the ocean. When they reach coastlines, the force can be devastating.

The Impact

The first wave of a tsunami is not always the largest, and the threat can persist for hours after the initial impact. As tsunamis move into shallow coastal waters, their wave heights increase dramatically, sometimes exceeding 30 feet—while their speed decreases, allowing the water to surge inland with tremendous force, demolishing structures, sweeping people, vehicles, and debris away, and causing widespread destruction to homes and infrastructure. In addition to the immediate danger, subsequent flooding can contaminate water sources, damage building structures, promote mold growth, and increase the risk of communicable diseases due to overcrowded shelters and disrupted sanitation systems. Long-term displacement of residents is a common consequence.

Susceptible Populations

Coastal communities are especially vulnerable to tsunami hazards due to their location in low-lying areas near the shoreline. Specifically, Pacific coastal states like Hawaii, Alaska, Washington, Oregon, and California face higher risks due to their proximity to major fault lines and volcanic activity zones. Populations with limited access to emergency communication systems or transportation may not receive timely warnings or be able to evacuate safely.

FEMA’s Tsunami National Risk Index. To visit the page, click the graphic .

 

Preparing for a Tsunami

Being prepared before a tsunami strike can save lives and reduce the risk of injury or loss. The following steps are recommended to help you and your community stay safe. Visit Ready.gov for more information.

  • Sign up for local emergency alerts, Emergency Alert System (EAS) and National Oceanic and Atmospheric Administration (NOAA) Weather Radio and NOAA Weather updates.
  • Know your evacuation zone and routes.
  • Prepare a disaster kit with food, water, medications, and first aid.
  • Practice evacuation drills, especially for schools and group housing.
  • Build or retrofit housing to meet flood and seismic codes.

During a Tsunami Warning

If a tsunami warning is issued, act quickly and follow official guidance to protect yourself and others. Time is critical, and swift evacuation can save lives. Visit Weather.gov for additional information.

  • Evacuate immediately if instructed to do so by authorities.
  • Move inland or to higher ground without delay.
  • Avoid coastlines, rivers, and low-lying areas.
  • Do not return until officials declare it safe.

After a Tsunami

Even after the waves have passed, serious hazards may remain. Stay alert and follow safety guidance to protect your health and wellbeing. Visit Weather.gov for additional information.

  • Avoid floodwaters because they may be contaminated.
  • Watch for structural hazards and avoid entering damaged buildings.
  • Report gas leaks, downed power lines, and other dangers.
  • Access emergency medical and housing support if needed.
  • Keep listening to NOAA Weather Radio or local radio to get the latest updates about when it is safe to return.

Resources

NOAA Tsunami Program
The NOAA Tsunami Program brings together several agencies to reduce the impact of tsunamis. Led by the National Weather Service (NWS), it works in collaboration with other parts of NOAA, such as Oceanic and Atmospheric Research, the National Ocean Service, and the Environmental Satellite and Data division. [url; NOAA, 2025]

U.S. Tsunami Warning System 
The U.S. Tsunami Warning System is an official source for real-time tsunami alerts, forecasts, and warnings from the U.S. National Tsunami Warning Center. It provides up-to-date information on tsunami activity, including maps, bulletins, and safety instructions. [url; NOAA, 2025]

National Tsunami Hazard Mitigation Program
The National Tsunami Hazard Mitigation Program (NTHMP), part of the National Weather Service’s Tsunami Program, is a coordinated nationwide initiative aimed at reducing the impact of tsunamis through public education, hazard assessments, community preparedness, and improved warning systems. [url; NOAA, 2025]

TsunamiReady® Program 
The TsunamiReady program serves as a national framework for helping communities reduce tsunami risk and enhance public safety. It outlines the criteria for becoming a recognized TsunamiReady community and provides guidance on improving emergency response capabilities. This site supports local leaders, schools, and emergency managers in building resilience and saving lives. [url; NOAA, 2025]

Tsunami Safety 
The Tsunami Safety website provides essential guidance on how to stay safe before, during, and after a tsunami. It emphasizes that while tsunamis are rare and unpredictable, preparation and awareness can save lives. [url; NOAA, 2025]

Caribbean Tsunami Warning Program
Tailored for the Caribbean region, this website serves as a valuable resource offering tsunami preparedness tools and training materials. It includes evacuation maps, port authority guidelines, and region-specific planning support to enhance community readiness. [url; NOAA, 2025]

International Tsunami Information Center
The Intergovernmental Coordination Group for the Pacific Tsunami Warning and Mitigation System (ICG/PTWS) provides vital information on tsunami risks in the Pacific, supports early warning systems, and promotes regional preparedness through coordinated drills and training. [url; UNESCO, 2025]

Center for Operational Oceanographic Products and Services (CO-OPS)
The CO-OPS website offers real-time sea-level data and tsunami wave detection from coastal gauges. It includes live charts, historical records, and alerts to support early warning, emergency response, and post-event analysis. This resource supports both early warning efforts and post-event analysis for coastal communities. [url; NOAA, 2025]

U.S. Geological Survey (USGS) 
USGS provides clear, science-based explanations of how tsunamis form. It showcases articles on related topics such as earthquakes and other natural hazards, providing valuable scientific insights on tsunami risks. [url; NOAA, 2025]

Recent Tsunami Events

The 2022 Tonga Volcanic Eruption and Tsunami: A massive undersea volcanic eruption in the South Pacific triggered tsunamis that affected Tonga, the Pacific Islands, and parts of the U.S. West Coast.

The 2011 Tōhoku, Japan Tsunami: One of the most devastating tsunamis in recent history. It was caused by a 9.0 magnitude earthquake, with waves reaching over 130 feet causing widespread destruction and a nuclear crisis.

 

 

Latest page update: July 28, 2025.