Tsunamis – Vulnerability Assessment

Lituya Bay After 1958 Tsunami[4]
Read More

The largest source region for tsunamis is in the Pacific Ocean with 71% of all occurrences. The remaining occurrences of tsunamis happen in the Mediterranean Sea (15%), Caribbean Sea and Atlantic Ocean (7%), Indian Ocean (6%), and finally the Black Sea (1%). Of all tsunamis, 83% are produced directly by earthquakes.[1]

Debris Falls Can Cause Tsunamis
Landslides/rockslides (or icefalls) into water or landslides under the ocean surface can generate sufficient displacement of water to produce tsunamis as well.

One such rockfall occurred Lituya Bay, Alaska. On July 9, 1958, an 8.3 magnitude earthquake triggered a landslide that caused 30 million cubic meters of rock and ice to fall into the narrow inlet of Lituya Bay. The sudden displacement of water resulted in a wave of 516 meters (1,720 feet) in height. This is the highest recorded megatsunami and the largest known in modern times.[2]

Tsunami Vulnerability Assessment Questions

To assess your vulnerability to the threat of a Tsunami to your family and property, perform an assessment to determine if you have knowledge of, are prepared and/or have a plan by answering the following questions:

General All-Hazard Questions:

  • Have you determined the disaster risks in your locale and the hazards that accompany them?
  • Do you know the emergency warning signals and alert notifications used in your community?
  • Have you instructed family members how to shut off water, gas and electricity to your house?
  • Have you made the necessary property preparations to reduce the damage from the hazard?
  • Do you have a backup generator in case of a prolonged power failure?
  • Have you purchased insurance (property, health, life, and/or hazard type)?
  • Have you made the necessary financial arrangements in case of a sudden evacuation and power outage that shuts down local ATMs and banks?
  • have you organized important documents and records and stored them in a portable lock box or safe-deposit box?
  • Have you performed a home inventory video taping the contents stored them in a portable lock box or safe-deposit box?
  • Does your family have an established Emergency Communication Plan and evacuation plan in place and asked an out-of-state person to serve as the “family contact”?
  • Have you assembled a shelter-in-place Emergency Supplies Kit in case you have to shelter at home and you are without power?
  • Have you assembled a mobile Emergency Supplies Kit that can serve as a “grab and go” bag?
  • Are you or someone in your family trained in first aid and CPR?
  • Have you made they necessary preparations and arrangements for pets, seniors, and the disabled?
  • Have you familiarized yourself with the emergency plans of your family member’s employment building, school, day care center, or nursing home?

Hazard Specific Questions:

  • Do you understand the difference between a tsunami Information bulletin, Advisory, Watch and Warning?
  • Do you know your distance from the shore and height above sea level?
  • Do you understand what it means if the ocean suddenly recedes from the shore?
  • Are you aware of the evacuation routes for your community?

Tsunami Vulnerability Map

This map displays tsunami sources (1650 B.C. – 2010 A.D.) from earthquakes, volcanic eruptions, landslides, or other causes.[3]



  1. National Weather Service – Jetstream – Online School for Weather: http://www.srh.noaa.gov/jetstream/tsunami/locations.htm
  2. National Weather Service – Jetstream – Online School for Weather: http://www.srh.noaa.gov/jetstream/tsunami/locations.htm
  3. Image Source: http://www.srh.noaa.gov/jetstream/tsunami/locations.htm [Accessed August 15, 2013]
  4. Image Sorce: http://en.wikipedia.org/wiki/1958_Lituya_Bay_megatsunami [Accessed August 15, 2013]