Last January 15, the eruption of a underwater volcano in Tonga shook the whole world. Literally. And it is that the resulting disturbance caused tsunamis in several countries beyond this nation of the Polynesia.
Two women they died in Peru, more than 10,000 kilometers away from Tonga drowned by big waves. Unlike other countries that are also very far away, such as Canada or Chile, in Peru the tsunami warning was not issued. It seemed unlikely that he could get this far, but he did. The rise in sea level also generated some damage from floods in the united states and even here in Spain the atmospheric disturbance could be felt in a phenomenon known as “meteotsunami”.
But why? What does the underwater volcano in Tonga have that, for example, the palm volcano? To begin with, an eruption under the sea is not the same as an eruption above the surface. But there are more characteristics that have turned the Tongan one into a whole clockmaking bomb. In fact, he had already given some notices in recent years. Until in the last month. But none had been as huge as this last one.
What is an underwater volcano?
One of the keys that has made the Tonga eruption so intense has been that it is a volcano submarine.
This means that the eruption is generated by the movement of the oceanic ridge plates and that the volcano in question is located on the seabed, without reaching the surface.
In the Canary Islands, where the ashes of the volcano of Cumbrevieja, also have experiences with submarine volcanoes. Although it is on another island, El Hierro, where the Tagoro, emerged from an eruption that occurred in 2011. That was not even similar to the one in Tonga. Neither have those that have occurred in recent years. What has it had then to be so explosive?
Chronicle of an explosion foretold
Shane Cronin, professor of Earth Sciences at the University of Auckland, in New Zealand, is one of the scientists who best knows the underwater volcano of Hunga Tonga.
Together with his team, he has studied its eruptions since 2009, when some magma and steam jets across the sea.
For this reason, they have been among the first researchers to embark on studying the latter big explosion. And, as he explained in an article for The Conversation, have discovered that, possibly, the previous ones were a warning of what was to come. But you couldn’t know exactly. Simply, once they have occurred, you can analyze the chemical trail they leave and establish relations between them.
On this occasion it seems likely that those small eruptions were the signal that the system was breaking down. recharging with magma for a big event like the one that happened on January 15.
Although the truth is that, in a certain way, a great eruption could be predicted in this century. Volcanic ash deposits have been found throughout the Tonga undersea volcano area that appear to correspond to two major eruptions in the past. Thanks to the radiocarbon dating, observed that such explosive events have occurred on the islands with about 1,000 years apartyes And the last one occurred approximately in the year 1100 after Christ; so, based on that, it was time for another in this century.
The peculiarities of the eruption of the underwater volcano of Tonga
Despite everything said above, the exact date on which the great eruption of the underwater volcano in Tonga would occur could not be known in advance.
Not even a small one could be foreseen, but this one also has great peculiarities that explain its explosiveness. And the key is in the temperature.
In his article, the professor at the University of Auckland explains that if the magma released by the submarine volcano rises slowly through the sea, a thin film of vapor between magma and water. This produces the necessary insulation to prevent the magma, at around 1,200ºC, from cooling down. But if the magma is quickly expelled from a ground covered with volcanic steam, things change. In that case, even if the vapor layer had formed, it would be interrupted and the magma would enter direct contact with cold water.
This process is known as “fuel-refrigerant interaction” or “steam explosion”, because it generates a very violent boiling. It is common in volcanoes, but it is also associated with other types of phenomena. For example, it is believed that much of the destruction caused by the chernobyl disaster in 1986 was due precisely to this reaction. Initially, it was the water used to cool the reactor that could cause the reaction by coming into direct contact with the hot nuclear fuel. However, the situation could have been even worse when the water that was used to extinguish the fires and cool the area was added to the equation. For this reason, tunnels were built under the reactor that would serve to drain this water.
Tsunamis and meteotsunamis thousands of kilometers away
This great explosion, whose origin we already know, has not been felt only in Polynesia. His expansive wave generated large waves that have lashed the coast of countries thousands of kilometers away. And although in other places they have not seen the sea trying to touch the sky, they have experienced something known as atmospheric tsunami or meteotsunami.
It occurs when a very sudden drop in atmospheric pressure causes strong variations in high tides. In Spain it is quite common on the islands. In fact, it has its own name. In the Balearic Islands it is known as rissaga, which means hangover in Menorcan. And in the Canary Islands like “Tides of the Pine”, since it is common that they occur annually coinciding with the festivity of the Virgen del Pino, on September 8.
Significant damage can be caused in seaports. For example, in 2006 there was a rissaga very intense in Port of Ciutadella, in Minorca. The tides had abrupt changes that reached 4 meters, causing significant damage to many boats.
This time it has not been so strong. After all, the source of the disturbance was almost 18,000 kilometers away. However, the barometers in the area, as well as in practically the rest of the world, did shake because of the explosion.
And is not for less. According to new calculations by Cronin published today by media of all the world. This could be the largest volcanic eruption to occur on the planet in last 30 years. Start strong this 2022.