An ocean wave.
A tsunami is a series of enormous waves created by an underwater disturbance usually associated with earthquakes occurring below or near the ocean.
Photo:Raeford Dwyer Photography

Promoting national and local risk reduction plans

In 2020, World Tsunami Awareness Day encourages the development of national and community-level, local disaster risk reduction strategies to save more lives against disasters. This year’s observance promotes "Sendai Seven Campaign,” target (e).

By the year 2030, an estimated 50 per cent of the world's population will live in coastal areas exposed to flooding, storms and tsunamis. Having plans and policies in place to reduce tsunami impacts will help to build more resilience and protect populations at risk. Do you have a national or a local plan in place to anticipate a tsunami?

In December 2015, the UN General Assembly designated 5 November as World Tsunami Awareness Day, calling on countries, international bodies and civil society to raise tsunami awareness and share innovative approaches to risk reduction.

World Tsunami Awareness Day was the brainchild of Japan, which due to its repeated, bitter experience has over the years built up major expertise in areas such as tsunami early warning, public action and building back better after a disaster to reduce future impacts. UN Disaster Risk Reduction (UNDRR) facilitates the observance of World Tsunami Awareness Day in collaboration with the rest of the United Nations system.

Social media card illustrating a tsunami ready community in India.

Background

Tsunamis are rare events but can be extremely deadly. In the past 100 years, 58 of them have claimed more than 260,000 lives, or an average of 4,600 per disaster, surpassing any other natural hazard. The highest number of deaths in that period was in the Indian Ocean tsunami of December 2004. It caused an estimated 227,000 fatalities in 14 countries, with Indonesia, Sri Lanka, India and Thailand hardest-hit.

Just three weeks after that the international community came together in Kobe, in Japan’s Hyogo region. Governments adopted the 10-year Hyogo Framework for Action, the first comprehensive global agreement on disaster risk reduction.

They also created the Indian Ocean Tsunami Warning and Mitigation System, which boasts scores of seismographic and sea-level monitoring stations and disseminates alerts to national tsunami information centres.

Rapid urbanization and growing tourism in tsunami-prone regions are putting ever-more people in harm’s way. That makes the reduction of risk a key factor if the world is to achieve substantial reductions in disaster mortality – a primary goal of the Sendai Framework, the 15-year international agreement adopted in March 2015 to succeed the Hyogo Framework.

What are tsunamis?

The word "tsunami" comprises the Japanese words "tsu" (meaning harbour) and "nami" (meaning wave). A tsunami is a series of enormous waves created by an underwater disturbance usually associated with earthquakes occurring below or near the ocean.

Volcanic eruptions, submarine landslides, and coastal rock falls can also generate a tsunami, as can a large asteroid impacting the ocean. They originate from a vertical movement of the sea floor with the consequent displacement of water mass.

Tsunami waves often look like walls of water and can attack the shoreline and be dangerous for hours, with waves coming every 5 to 60 minutes.

The first wave may not be the largest, and often it is the 2nd, 3rd, 4th or even later waves that are the biggest. After one wave inundates, or floods inland, it recedes seaward often as far as a person can see, so the seafloor is exposed. The next wave then rushes ashore within minutes and carries with it many floating debris that were destroyed by previous waves.

What are the causes of tsunamis?

Earthquakes

It can be generated by movements along fault zones associated with plate boundaries.

Most strong earthquakes occur in subduction zones where an ocean plate slides under a continental plate or another younger ocean plate.

All earthquakes do not cause tsunamis. There are four conditions necessary for an earthquake to cause a tsunami:

  • The earthquake must occur beneath the ocean or cause material to slide into the ocean.
  • The earthquake must be strong, at least magnitude6.5 on the Richter Scale
  • The earthquake must rupture the Earth’s surface and it must occur at shallow depth – less than 70km below the surface of the Earth.
  • The earthquake must cause vertical movement of the sea floor (up to several metres).

Landslides

A landslide which occurs along the coast can force large amounts of water into the sea, disturbing the water and generate a tsunami. Underwater landslides can also result in tsunamis when the material loosened by the landslide moves violently, pushing the water in front of it.

Volcanic eruptions

Although relatively infrequent, violent volcanic eruptions also represent impulsive disturbances, which can displace a great volume of water and generate extremely destructive tsunami waves in the immediate source area.

One of the largest and most destructive tsunamis ever recorded was generated in August 26, 1883 after the explosion and collapse of the volcano of Krakatoa (Krakatau), in Indonesia. This explosion generated waves that reached 135 feet, destroyed coastal towns and villages along the Sunda Strait in both the islands of Java and Sumatra, killing 36,417 people.

Extraterrestrial collisions

Tsunamis caused by extraterrestrial collision (i.e. asteroids, meteors) are an extremely rare occurrence. Although no meteor/asteroid-induced tsunamis have been recorded in recent history, scientists realize that if these celestial bodies should strike the ocean, a large volume of water would undoubtedly be displaced to cause a tsunami.

World Tsunami Awareness Day logo

Social media

Use the assets to share the social media campaign. Join the conversation! #TsunamiDay #Plan2Survive

Did you know?

  • Tsunamis are rare events, but they are the deadliest and costliest among all hazards. The 2011 Tohoku Earthquake in Japan cost more than US$235 billion and was the costliest disaster in world history.
  • Over 700 million people live in low-lying coastal areas and Small Island Developing States exposed to extreme sea-level events including tsunamis.
  • Over the past two decades, tsunamis have accounted for almost 10 percent of economic losses from disasters, setting back development gains, especially in countries that border the Indian and Pacific Oceans.

Events

Illustration of tsunami evacuation signs near houses by the water.

UNESCO Online Lecture Series
Going “Tsunami Ready” in the Indian Ocean

The six-part lecture series targeted community leaders, disaster management offices, NGOs and citizens at large to inform about the Tsunami Ready Program and encouraged them to implement the program’s risk reduction protocols and indicators to be recognized as Tsunami Ready by UNESCO’s Intergovernmental Oceanographic Commission (IOC). Visit the IOC event page to learn more and to watch all six sessions online.

UNDRR
World Tsunami Awareness Day: Ready for the Next Wave!

UNDRR brings together a High-Level Panel to discuss implementing disaster risk reduction plans and are preparing to face the next tsunami. Watch now.

UNDRR
Third World Tsunami Museum Virtual Conference

This digital event highlighted the work of existing disaster museum experiences and promotes the network of disaster museums in keeping the memory of past disasters alive. Watch now.

Watch

Tsunami ready communities

In 2009 a devastating tsunami destroyed 20 villages in Samoa and 187 people lost their lives. Today Tsunami Ready plans have been mainstreamed into the disaster management plans for over 380 schools, including regular drills and education programs for students. Watch the stories of other tsunami ready communities.

Portrait of two people

In line with the International Disaster Risk Reduction Day, UNESCO Office Jakarta introduced its ongoing project on documenting the survivors and eyewitnesses story of the 1927, 1938, 1968, and 2018 earthquakes and tsunamis in Central Sulawesi. Their stories will be revealed on World Tsunami Awareness Day, 5 November 2020.

Petra Nemkova facing a girl as both smile.

Czech model and entrepreneur Petra Nemcova is the official UN Disaster Risk Reduction World Tsunami Awareness Advocate, which is commemorated on 5 November every year. Petra Nemcova not only survived the 2004 Indian Ocean tsunami in Thailand but also found a way to continue living and sharing her experience at the service of people affected by disasters.

Geometric illustration with the Secretariat building at UNHQ, New York.

International days are occasions to educate the public on issues of concern, to mobilize political will and resources to address global problems, and to celebrate and reinforce achievements of humanity. The existence of international days predates the establishment of the United Nations, but the UN has embraced them as a powerful advocacy tool. We also mark other UN observances.