Saturday, December 4

Questions and answers about the sulfur dioxide and the ash cloud of the La Palma volcano


The main unknown is how long the eruption of the La Palma volcano will last. It is not the same that it is a few days that it is extended in time for months, as it happened with the underwater volcano of El Hierro. What is clear, experts say, is that the Cumbre Vieja volcano is low-explosive. What is expected is that its eruptive column, the ashes and gases expelled into the atmosphere, will not reach more than three or four kilometers in height. If this column does not rise to much higher layers, these gases and ashes will not have great mobility at the regional or continental level.

These are the ‘geoclaves’ of what is happening on La Palma

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Nor does it seem likely that airports across Europe will have to close due to the ash cloud, as happened with Iceland’s Eyjafjallajökull volcano in 2010, which paralyzed air traffic for a week. The worst part, experts predict, will be borne by the surface on which the great lava tongue advances. “The problem really is that La Palma is a habitable zone and unfortunately the descent of the streams is going to take everything in its path”, explains Daniel Santos, a meteorologist at the Danish Meteorological Center.

Sulfur dioxide, which can irritate the eyes and airways, as well as lead to acid rain, is also not of great concern at this time. “The concentrations are so extremely low that they do not seem problematic in that regard, except for people who are very close to the volcano or who are working there,” says Santos.

Is there a danger to air traffic?

The La Palma volcano is of the Strombolian type, which implies a moderate explosiveness. “A priori there is no reason to think about a crisis of airspace closure or anything similar as it did in Iceland. Airports throughout Europe are not going to be closed”, predicts the expert in volcanology and professor of Petrology and Geochemistry of the Complutense University of Madrid Eusemio Ancochea. “It has nothing to do with the volcano in Iceland. We are still at the beginning of the eruption and we do not know everything, but due to the eruptions that have historically taken place on La Palma and the type of eruption that it is, the gases and ash would not arrive. never at high levels of the atmosphere, “says Santos.

“In general, the eruptive columns reach high levels of the atmosphere that are then distributed by the winds. It can have a regional distribution, of an entire continent, as happened with the Eyjafjallajökull or as it happens in America, affecting Argentina and Chile as a whole. These types of eruptions are much more violent and explosive than the one we have at the moment, “says the expert.

The eruptive column that has been generated on La Palma is between three and four kilometers long and, Santos says, “we would have to be talking about 17 or 18 kilometers so that this could have a global distribution, as well as a very different type of eruption from the one we’re having right now. ” “Explosive indices are measured with the amount of material that comes out, and until the eruption ends it is not known, but this seems a moderate to low explosiveness,” Ancochea concludes.

What is sulfur dioxide?

It is a gas (SO2) that is released in volcanic eruptions as magma rises to the surface. “Sulfur dioxide is one of the volcanic gases that accompany eruptions. It is not unusual. Magma carries gases that are dissolved at great depths and when they reach the surface they separate and come out as an independent gas. It is not a an eruption that has a special content in certain gases “, points out the volcanologist.

“There may be SO2, there may be hydrofluoric acid. It is not so frequent, but there are eruptions where there is hydrofluoric acid that practically burns when it falls, especially if it is mixed with water. Not here,” he adds.

How far could the ash cloud go?

At the moment, the ash cloud is not expected to drift to another continent. “It depends on in which direction the winds move it. The most important thing is that both the ash and the particles that are emitted are monitored. This monitoring is done from Toulouse [desde el Toulouse Volcanic Ash Advisory Centre]”, explains the meteorologist.

“From there, a control of the effects of these ashes on air traffic is established. Toulouse has issued a series of warnings, but the amount of ash, due to the type of volcano, does not reach very high. Depending on the type of volcano, There are times when the generated cloud rises very high because the volcano emits ash with great force and these are the ones that most influence air traffic “, he adds. In the case of the Icelandic volcano, he recalls, “all air traffic in Europe was closed and it affected a large part of the northern hemisphere.”

What does sulfur dioxide produce in living beings?

Irritation to eyes, respiratory tract and skin. “Right now, the concentrations are so extremely low that they don’t seem problematic in that regard, except for people who are very close to the volcano or who are working there. Right now there is no risk about that, not even in terms of the emissions of CO2 “, indicates Santos.

On the other hand, he adds, “it has been shown that volcanoes can affect the weather and climate due to the great emission of gases and dust in the atmosphere, but this volcano is not one of explosives.” “The problem really is that the washings are going to take everything in their path”, although he acknowledges that when it rains in the surroundings it could produce acid rain, since volcanic eruptions inject water vapor, carbon dioxide, sulfur dioxide, hydrochloric acid, hydrofluoric acid and ash.

What happens when lava touches sea water?

That there is a large temperature contrast that can cause violent reactions. “The explosions when touching the water are produced by thermal contrast when touching the sea. It is as if you pour water into a pan. What you will see is bubbling or a lot of water vapor because the lava reaches more than 1,000 degrees and touches water that is to 18, 19 or 20 degrees, reason why an instantaneous evaporation of the water and gurgling takes place “, details the meteorologist.

There is an escape of water vapor, but it is not like the one in Iceland. It is one thing for the water to enter the crater and another thing for a lava flow to reach the water. For a wash to reach the water is like pouring oil into a bathtub. Maybe it produces explosions, but nothing more. Small explosions that can be dangerous if you are close and especially columns of white steam. While the vapor that we see in the crater is gray or brown, “adds the volcanologist.

When do airspaces close?

When the ashes affect the visibility or the turbines of the aircraft themselves. “The ashes affect aircraft engines, it is not only about visibility problems. For now the clouds that are being generated are below flight level,” concludes Santos.


We premiered ‘Un tema al día’, the daily podcast of elDiario.es with Juanlu Sánchez, talking about the La Palma volcano. You have more information here. You can follow it on Podimo and other platforms.





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