TsunamiA 15-year old girl is rescued from the rubble of her house in central Sulawesi in Indonesia hit by an earthquake and tsunami in September 2018. This is the sixth fatal tsunami to strike the country since the huge 2004 Indian Ocean tsunami. According to the UN Office for Disaster Risk Reduction (UNISDR), Indonesia has suffered more deaths from tsunamis than any other country. © UNICEF/Tirto.id/@Arimacswilander
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.
An aerial view of the vast destruction of the Indonesian coast, between the towns of Banda Aceh and Meulaboh, caused by the 2004 Indian Ocean tsunami. UN Photo/Evan Schneider
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.