On 5th November 2019, the World Tsunami Awareness Day is promoting the “Sendai Seven Campaign” which focuses on reducing disaster damage to critical infrastructure and disruption of basic services.
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.
Over 700 million people live in low-lying coastal areas and Small Island Developing States exposed to extreme sea-level events including tsunamis (IPCC).
Tsunami is a series of giant waves. In Japanese, tsunami means ‘Harbour Wave’. A wave is created when energy passes through water. Moving air or wind provides energy to water, forming regular waves.
While on the ocean floor, when a tectonic plate suddenly slides beneath the other, the resulting earthquake releases tremendous amount of energy. This energy spreads outward from the point of earthquake, triggering waves that can form tsunami. Initially, these waves are small in size but they travel at great speeds. However, when the waves approach the shore, the rising seabed obstructs the energy of waves. This slows down the speed of waves. But the energy flux must remain constant leading to an increase in height of the waves, thus resulting in tsunami.