Tsunami are a clear and ever-present danger

In modern times, nine of the 10 strongest earthquakes ever recorded were accompanied by tsunami that often resulted in death and devastation for many communities taken completely unawares.

The list stretches as far back as January 1906 when a tsunami triggered by a magnitude 8.8 earthquake is reported to have killed between 500 and 1,500 people in Ecuador and Colombia, 43 years before a tsunami early warning system was introduced in the Pacific Ocean in 1949.

One of the most striking things about this list is that eight of these earthquake/tsunami events have occurred within living memory.

And, according to an analysis of the emergency events data base maintained by the Centre for Research on the Epidemiology of Disasters, the deadliest of these have all occurred within the last 20 years.

This review puts lives lost from tsunami at 251,770, and economic losses at $280 billion between 1998 and 2017. This compares with 998 deaths and $ 2.7 billion in economic losses for the previous two decades, 1978 to 1997. Of course, 40 years is not a very long time in which to uncover definitive trends when it comes to analysis of earthquakes and tsunamis, which have very unpredictable return times unlike weather events such as typhoons and heat waves.

Nonetheless, this level of losses should be of great concern to countries that find themselves trying to protect vulnerable populations living on coastlines exposed to this most deadly of natural hazards. These coastlines are also home to much critical infrastructure including sea ports, airports, nuclear power plants, large cities and towns.

One estimate is that tsunami average more than 4,600 deaths for each occurrence, a much higher mortality rate than any other natural hazard.

All this history of losses caused by tsunami underlines the importance of constantly raising awareness of tsunami risk, which is why it is now the custom to mark World Tsunami Awareness Day on Nov. 5 every year.

The day falls 33 days after the tsunami and earthquake that claimed over 2,000 lives in Central Sulawesi, Indonesia. Many more are still missing. This served as a grim reminder that exposure to tsunami risk is in lock-step with population growth in coastal areas around the world’s major oceans, including the Pacific, the Indian, Atlantic Oceans, and the Mediterranean and its connecting seas.

It is important that robust early warning systems are put in place. However, we cannot become over-reliant on technology. People living in tsunami zones, once they experience an earthquake, should have the engrained instinct to flee to higher ground immediately and remain there until the danger has passed. It requires continued advocacy and education in order to bring about behavioral change but this is what will save lives.

In Hawaii, which has experienced over 100 recorded tsunami, they have a proverb: “Never turn your back on the sea. Unlike hurricanes, a tsunami has no season. It can strike at any time, both day and night, without warning, or little warning.”

Complacency is the greatest threat in the face of a natural hazard that knows no time or season. Memory and awareness raising are essential in keeping the risk at the forefront of our minds.

Mami Mizutori is the United Nations Secretary-General’s Special Representative for Disaster Risk Reduction and head of the U.N. Office for Disaster Risk Reduction (www.unisdr.org).