Potential Hazards/Risks in Tonga
Tonga is vulnerable to a number of natural hazards due to its location and topographical nature. The main hazards are earthquake, tsunami, tropical cyclones and drought. It is important that the people of Tonga understand what these hazards are, how they come about, the impact of these hazards and how to prepare for them. The following includes some important facts about hazards.
Tropical Cyclone Risks: The risk of tropical cyclones in Tonga is high, since the country is located south of the equator in an area prone to frequent tropical cyclones with damaging wind, rain, and storm surge, particularly during the Pacific cyclone season. The cyclone season in Tonga is from November to April, however the peak time for tropical cyclones in Tonga is from January to March with most events occurring in February. The Tonga Meteorological Service is also continuing to monitor El Niño conditions. Usually in an El Niño year Tonga can expect to receive 2 cyclones.
Tsunami Risks: Since 1950, twelve recorded tsunamis have originated in Tonga. Of these, nine were caused by earthquakes and three by volcanic eruptions, including the HT-HH event. Tsunamis are caused by underwater earthquakes, but landslides, volcanic eruptions, calving icebergs, and (very rarely) meteorite impacts can also generate tsunamis. These types of events can cause large disturbances in the surface of the ocean causing large volumes of water to move.
Earthquake Risks: Four out of 5 of the world's earthquakes take place along the rim of the Pacific Ocean, a zone called the Pacific Ring of Fire. Sometimes there are many small earthquakes before the big one. These small ones are called foreshocks. After the big earthquake, the main shock, again there may be many small quakes. These are called aftershocks. Most earthquakes last a minute or less. Many earthquakes happen on the ocean floor. Big ocean waves can form after an earthquake resulting in a tsunami. The main killers in earthquakes are falling buildings, fires, landslides, avalanches and tsunamis.
Volcanos Risks: Tonga is home to 21 known volcanos, seven of which have erupted in the last 20 years. Two percent of the population lives less than 30 km from a volcano. The unprecedented impact of the HT-HH volcano in 2022 highlighted that the risk of volcanic hazards in Tonga is higher than previously understood. More than 84% of the population were affected by the HT-HH volcanic eruption and subsequent tsunami
Drought Risks: Drought is often a slow complex emergency that can affect livestock and the livelihoods and health of those impacted. Major droughts usually occur in Tonga during El Niño years. Projections show that droughts and increased aridity are likely to increase in Tonga.