Since time immemorial, human beings have always wanted to act on volcanoes. One of the questions that has always been asked is how does a volcano go out. The question is whether the human being has the capacity to pay for a volcano that is in full eruption.
In this article we are going to explain how a volcano goes out, how it can be done and some curiosities.
Volcanic activity
According to the Smithsonian Institution's Global Volcanic Activity Database, there are currently about 1396 active volcanoes around the world. Of these, some 70 volcanoes, including the Cumbre Vieja on La Palma, have erupted so far this year.
"A volcano is considered active if it erupted in the last 10.000 years," says petrologist María José Huertas. The Canary Islands are very active, although it is difficult to predict when the volcano will start to wake up. Between long periods of inactivity, ranging from years to decades, the signs of a volcano's reactivation are not always obvious. Between long periods of inactivity, ranging from years to decades, the signs of a volcano's reactivation are not always obvious.
With the exception of the Cumbre Vieja area of La Palma, several seismic swarms from October 2017 may have marked the beginning of the recovery of the Canarian volcano after 46 years of calm. They may be the first evidence of volcanic activity after the last eruption (Volcán Teneguía) in 1971.
This series of recorded earthquakes simply indicates a strong supply of magmatic fluid at a depth of 25 kilometers. This is revealed by a team led by the geologist Vicente Soler from the Institute of Natural Products and Agrarian Biology (IPNA-CSIC) in the Journal of Volcanology and Geothermal Research.
Before the first series of earthquakes, scientists recorded changes in gas emissions, with higher concentrations of radioactive chemical elements such as hydrogen and radon in the area near the earthquakes, suggesting "deep gas entry."
In the second colony, an increase in the concentrations of radon and thoron, an isotope of radon, was still observed, produced by the decomposition in the soil of another radioactive element, thorium. With all these data, the experts deduced the existence of stagnant magma intrusions several kilometers deep.
Earthquakes, deformation and gas
The magma wriggles between the rocks in shallow chambers (magma chambers) in the crust below the volcano. In a persistent imbalance, the pressure is high due to the presence of gas, which makes this liquid substance formed from molten rock above 1.200°C into an unstable entity.
“His nature is to try to get to the surface, but for that he has to break those solid structures. That is why it looks for vulnerable areas within the crust where it can migrate”, explained the scientist.
Compared to the environment surrounds it, the magma is less dense and lighter, and tends to escape to areas of lower pressure and depth (ie the surface). Due to its compounds and the gases that accompany it, which lubricate and alter the rocky environment making it more fragile and soft, the volcanic material seeks an outlet to the outside. Due to the presence of gas, the pressure is high, which makes the magma formed by lava above 1.200 ºC an unstable entity.
That is why the earthquakes that follow one another occur in greater numbers and are different from those caused by the movement of the earth's plates. They are the first evidence that volcanic activity can occur. "Without the earthquakes, the volcanic eruptions would not have developed," Huertas said.
“If there is a sudden increase in gas emissions, you already know what it is indicating. Maybe it's nothing: the magma quietly degasses as it releases them. Or very fresh pulses of magma can arrive with their gas and release it,” he continued.
“In the event of earthquakes, unusual gas activity, and uplift or heaving of the surface of La Palma, there clearly seem to be precursors to eruptive activity,” he emphasized. To do this, it is necessary to know the base level of the volcano, that is, the average number of earthquakes, the amount of gas emitted, etc. »
"You need to measure as many observables as possible. When the normally recorded average becomes anomalous, for example, more earthquakes are recorded, the amount of gas emitted increases, and if those anomalous observations remain unchanged over time, then one can speak reactivated or turbulent English,” said Janire Prudencio, Professor of Geophysics at the Andalusian Institute of Geophysics of the University of Granada (UGR).
Seismicity, deformation and the amount of gas emitted are the main indicators of the current state of the volcano. "There have to be several combinations to predict a volcanic eruption," Huertas said.
How does a volcano go out?
More than two weeks after the Strombolia eruption, the lava flow that has formed a band reaching the sea is more than a kilometer and a half wide and extends for more than 500 hectares, according to the Special Projects Steering Committee.
But things are changing every day. “Even every hour, because the eruption changes as the amount of gas it emits changes. At the moment when the magma begins to cool and the first mineral crystals form, the eruption changes. Over time, the rash changes. Everything is developing rapidly,” said the geologist.
For now, the eruption of the volcano, which suffered several landslides on the north face of the cone over the weekend, hastened the flow. But several scenarios were considered: after a few days, the magma chamber emptied and the eruption stopped; or the magma chamber connected to the magma chamber deep in the mantle was being replenished with newer, more primitive magma, and the eruption continued.
"No one knows how long it will last because it can be recharged with fresh material from the mantle," warns Huertas, although the average duration of the La Palma eruptions ranges between 27 and 84 days. It also affects how quickly it turns off. “You can do it faster or slower. These are unpredictable things that no one has dared to quantify at this time.
Currently, scientists from the UGR, together with researchers from INVOLCAN, the University of La Laguna and other foreign institutions, have taken samples of lava and ash (volcanic debris, small rock fragments) from the volcano to understand, on the one hand, the conditions and what happens. within it The process, on the other hand, is how the magmatic system evolves.
The inside of the garment It can be stored for months at temperatures between 200ºC and 400ºC. When this happens, the whole process stops: the cast cools down and contracts very slowly. They will lose volume and we will enter a different phase than the eruption. "The temperature inside the laundry room can be between 200 ºC and 400 ºC for months," reports Huertas. After that, it becomes solidified igneous rock.
I hope that with this information you can learn more about how a volcano has occurred.