Tsunami Risk Zones



Am I in danger?

Tsunami Risk Zones

Risk is often defined as a combination of the danger posted by an event (tsunami hazard), the vulnerability of people to an event (exposure, e.g., coastal communities), and the likelihood of the event occurring (probability of destructive tsunami). If you live along the coast in a tsunami hazard zone, you are at risk from tsunamis.

All oceanic regions of the world can experience tsunamis, but in the Pacific Ocean and its marginal seas, there is a much more frequent occurrence of large, destructive tsunamis because of the many large earthquakes along the margins of the Pacific Ocean.

All low lying coastal areas can be struck by tsunamis, some of them can be very large; their height can be as great as 10 meters or more (30 meters in extreme cases), and they can move inland several hundreds meters, depending on the slope of the ground.

A tsunami consists of a series of waves with crests arriving every 5 to 60 minutes. Often the first wave may not be the largest. The danger from a tsunami flooding and strong wave currents can last for several hours after the arrival of the first wave. Sometimes a tsunami initially causes the water near shore to recede, exposing the ocean floor.

The force of some tsunamis is enormous. Large rocks weighing several tons, along with boats and other debris, can be moved inland hundreds of meters by tsunami wave activity, and homes and buildings destroyed. All this material and water move with great force, and can kill or injure people.

Tsunamis can occur at any time, day or night, and they can travel up rivers and streams from the ocean. They also can easily wrap around islands and be just as dangerous on coasts not facing the source of the tsunami. 

For more information on historical tsunamis, click here

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Global tsunami source zones. Tsunami hazard exist in all oceans and basins, but occur most frequently in the Pacific Ocean. Tsunamis can occur anywhere and at any time because earthquakes cannot be accurately predicted. Courtesy of LDG-France.

Understanding Risk Behavior: The Fundamental Challenges
(NOAA Coastal Service Center)

Human exposure to risk from coastal hazards is increasing because vulnerable coastal areas are becoming more densely populated. Coastal hazards such as hurricanes and floods are predicted to become more intense as a result of climate change. Better risk communication can save lives, protect property, lessen damage to coastal economies, and create more resilient coastal communities that recover more quickly after a disaster.

What Is Risk?
Risk is often defined as a combination of the danger posed by an event (hazard), the vulnerability of people to an event (exposure), and the likelihood of the event occurring (probability). But why do two people exposed to the same level of risk behave differently? Why does one family evacuate for an oncoming storm while other neighbors stay? Because peoples’ behavior is also determined by their own perceptions and their own decision- making processes.

Risk perception
There are many models and frameworks that attempt to explain how people perceive and interpret risk. A common idea in the models is that people perceive risk from two dimensions: what they know about the risk, and how they feel about the risk. Feelings about risk are shaped by peoples’ past experiences, the opinions of their social networks, their level of control over the risk, and many other factors. Risk managers tend to pay too little attention to how people feel about the risk, focusing instead on increasing their knowledge. Conversely, the public tends to put a lot of emphasis on how they feel about the risk, sometimes ignoring important messages or information.

Making decisions in the face of risk
Perception can be seen as the first step in making a decision, followed by considering options, calculating which option is in your best interest, and then taking action. As with risk perception, psychological and social factors such as the decisions of friends and family, as well as physical circumstances such as mobility and access to transportation, impact how a person weighs the costs and benefits of different options. Many people use intuition or “rules of thumb” to make decisions, which can be helpful or harmful. Decision-making is rarely limited to two mutually exclusive options; there are often many alternate paths.

Risk Communication
Risk communication is a critical component of risk management. The ultimate goal of risk communication is generally to change peoples’ behavior in a given situation. And because research has repeatedly shown that behavior change is rarely achieved without highly tailored and carefully crafted messages, a keen understanding of audiences and their situations is essential to success.

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Featured Resources

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Regional Disaster Information Center (Latin America & the Caribbean)


A database of Spanish language materials focused on tsunami preparedness.
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Post-Tsunami Survey:
El Salvador Summary Video

Learn the basics of a post-tsunami survey.
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TsunamiTeacher USA
Tsunami Basics
  

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Learn the basics of tsunamis. Available in English and Samoan.

 
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Tsunami Awareness Poster


Awareness poster available in English, Chinese, French, Japanese, Korean, Portuguese, Singalese.

 
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Global Hazard Maps


Posters of Tsunami Sources, Significant Earthquakes and Significant Volcanic Eruptions. Also Tsunami Sources Icosohedron Globe.

 
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Tsunami, The Great Waves

Available in English, Spanish, French and Chinese.

 

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Tsunami Glossary


Available in English, Arabic, Spanish, French and Bahasa. 

 

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Where the First Wave Arrives in Minutes

Available in English, Bahasa, Spanish and French.
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TsunamiTeacher

DVD copies for PC and Macintosh computers are available free of charge from the ITIC, Hawaii (itic.tsunami@noaa.gov).

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