Wednesday, October 27

Why has the La Palma volcano erupted and what can happen now

More than thirty people from the National Geographic Institute work right now from La Palma, Tenerife and Madrid to mitigate the risk of the volcanic eruption that began at 3:12 p.m. this Sunday in La Palma and has already forced hundreds of residents to evacuate . The volcanologist Alicia Felpeto, with more than 25 years of experience, is one of the experts of this body dependent on the Ministry of Transport, Mobility and Urban Agenda. He explains the keys to what is happening in Cumbre Vieja.

How did the eruption occur?

Like all eruptions, it is produced by magma that rises until it rises to the surface. What happened until 3:12 p.m. this Sunday is a process of magmatic intrusion. The magma is rising and breaking the rocks of the crust, disarming the ground and releasing gas. It is what we monitor to know that the eruption is coming. Many of these intrusions do not reach the top, but today they have. Processes like this take place in all active volcanic zones.

Is it normal for there to be multiple mouths?

It is very common, especially at the beginning of the eruption, but in the Canary Islands it is also normal for there to be mouths separated by long distances. Sometimes they alternate and sometimes they appear together. There may be several active mouths or that within a few hours everything is concentrated in one. Or appear elsewhere.

Can you tell where other mouths are going to come out?

No. The dynamics of magma when it is so close to the surface, the terrain is so heterogeneous and there are so many influencing things that it is practically impossible. To guarantee security, what is usually done is to oversize the restricted access space. If when doing a simulation of where the lava is going to go there is a certain terrain, the restricted space is much larger. But zero risk does not exist.

What are the gases that we see coming out of our mouths?

Volcanoes emit a series of gases, which are mostly water vapor, CO2, and sulfurous compounds of sulfur, chlorine, and others. The white cloud that can be seen in the images is water vapor, but it also expels ash, small fragments of magma -which can be from several meters in diameter to dust-, which expel upwards, disperse and affect larger areas . The height depends on the type of rash. Until mid-afternoon, they were about 400 meters above the crater (the mouth), but in large eruptions, which are not expected on La Palma, they can reach tens of kilometers.

Are these ashes dangerous?

They are somewhat toxic and in large quantities can pollute the water. Ashes in suspension can bother the eyes, because it is a tremendously abrasive material, or scratch the glass of the car, but it is something that happens in large quantities, and should not happen if people do not approach the place. It also affects crops, but enriches soils.

What can we expect in the next few days?

The expectation is that this will continue to throw lava and some ash into the atmosphere. Historical eruptions on the island of La Palma have lasted between a little more than 20 and a little more than 80 days. That is the average of what happens. It can be shorter or longer, depending on the amount of magma. Although we can have an estimate, not all the magma ends up coming to the surface. They usually start by increasing the amount of material they eject very quickly and then go down more smoothly. When we see that descent, we can estimate that the eruption will end.

Have there been more eruptions of this type?

In the Canary archipelago there have been thirteen well-documented historical eruptions, since 1585. Six of them have occurred on La Palma, the island with the most eruptions. The last two were in 1971 and 1949.