Two days after the Hunga Tonga-Hunga Ha'apai eruption, 65 kilometers from Nukualofa, the capital of the Polynesian kingdom of Tonga, in the South Pacific, scientists continue to assess its consequences.
Satellite images taken by NASA confirm that the eruption reached 30 kilometers in altitude.
It is one of the largest eruptions recorded by satellite, somewhat smaller than the one caused by Pinatubo, in the Philippines, in 1991. At that time it was estimated that the ash cloud reached 40 kilometers and the emission of gases into the atmosphere caused a global decrease in half degree temperatures.
Andrew Gissing, one of those responsible for the development of the early warning system created by the Australian Government after the devastating tsunami of 2004, recalls in statements collected by the Science Media Center that "5% of all tsunamis in the world throughout history have been produced by volcanoes”. According to Gissing, "it is not clear if the volcano will produce another large eruption or lose strength, but it is likely that the activity will continue for the next few days." At the moment, there have already been three eruptions in the last four days.
The volcano is located in the volcanic arc known as the Pacific Ring of Fire. In that area, the Pacific tectonic plate sinks under the Indo-Australian plate. In that process, the descending plate heats up and melts the magma on it which flows to the surface forming a volcano. This area, which extends over 25,000 kilometers and reaches from southern South America to Alaska and Polynesia, concentrates 90% of earthquakes and 70% of active volcanoes. The most powerful eruptions known, such as Pinatubo in the Philippines or Krakatoa in Indonesia, have occurred in the region.
There, an eruption that took place in 1883 caused more than 35,000 deaths and produced a global drop in temperatures throughout the planet that did not return to climatic normality until five years later. Also in present-day Indonesia, but 75,000 years earlier, the Toba volcano exploded. The eruption, a thousand times more powerful than that of Krakatoa, has been associated with prolonged climate change that has been associated with a genetic bottleneck in the human species. According to this controversial theory, only between 1,000 and 10,000 breeding pairs of
Hannah Power, from the University of Newcastle (Australia), explained that a 1.19 meter wave was recorded in Nukualofa before the data flow was interrupted.
Waves of more than a meter have been observed on the islands of the region, but also in places as far away as the coasts of the entire American continent or the Japanese archipelago.
This large submarine volcano has a caldera six kilometers in diameter and a depth of 150 meters.
During its last eruption, between 2014 and 2015, a volcanic cone was produced that joined other small volcanic islands resulting from previous eruptions.
Satellite images taken hours before Saturday's eruption showed previous volcanic activity had almost completely destroyed the islet.
The evaluation of the damage in Tonga has not yet been completed because the eruption interrupted communications with the island, which are possible thanks to a submarine cable that connects this archipelago with that of Fiji. In the next few days, it is planned to send the help that those affected need, although these trips arouse other fears in the islanders. Curtis Tu'ihalangingie, Tonga's representative in Australia, expressed concern about the risk of the coronavirus reaching the island, which is so far free of covid, along with aid shipments. "We don't want to bring another wave, a tsunami of covid 19," Tu'ihalangingie told Reuters.
Some experts have taken advantage of the occasion to emphasize the importance of international cooperation in the face of this type of phenomenon. Andrew Tuper, a consultant for the natural hazard prevention company Natural Hazards Consulting and former co-director of the Australian Tsunami Warning Center, believes that "eruptions like this help reinforce the need for global cooperation on hazards of all kinds." On this occasion, the height of the waves was measured in part thanks to tide gauges installed by Australia in the Pacific and the clouds ejected into the atmosphere with information from satellites in Europe, Japan or the USA. “Our cooperation as a global community helps us to manage these events, including helping affected countries. But there is much more to do to better manage these natural hazards globally."has added. So far, no casualties have been identified in the regions closest to the eruption.
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