WorldNieves Sánchez, geologist: “The volcano of La Palma could be reactivating”

Nieves Sánchez, geologist: “The volcano of La Palma could be reactivating”



Nieves Sánchez has seen up close the terrible destruction that a volcano is capable of causing. In 2018, this researcher from the Geological and Mining Institute of Spain (IGME) traveled to the area devastated by Guatemala’s Fuego volcano, in one of the deadliest eruptions of recent years. His narrative shivers. “The volcano hit a very poor area,” he recalls. “There was a pyroclastic flow, a cloud of gas and rock at a very high temperature, which moved very quickly. The inhabitants of the area thought it was a lava eruption and left their homes to see it arrive. The cloud dragged them away. It is not known how many people died, there are only approximate calculations based on the number of light meters, but many people live there without electricity.”

Sánchez arrived well after the event. His aim was to oversee and improve a rudimentary early warning network to prevent further tragedies. It is simply a radio system so that watchers in high areas can alert valley dwellers to the arrival of a new flood or eruption. That same year, Sánchez traveled on a European Union and UN mission to the Caribbean island of São Vicente, where the volcano La Soufrière covered everything with tons of ash – so much so that authorities didn’t know what to do with it.

For a few weeks, Sánchez has been in La Palma watching the Cumbre Vieja volcano closely. This 52-year-old geophysicist from Madrid lives in Gran Canaria and has been studying volcanism on these islands for 13 years as an IGME employee. Currently, he works at the improvised forward command post at the visitor center in the Caldeira de Taburiente National Park. Where once there were tourists, now there are civil guards, military and scientists working side by side.

Sánchez represents the IGME on the scientific committee of Pevolca (Canary Islands Volcanic Emergency Plan). In this interview, she draws a sketch of the volcano based on the first scientific analyzes of lava, ash and gases. “The volcano shows no signs that it will stop tomorrow or later or in a week”, he warns.

In the last few hours, the lava tongues have become more fluid. IGME geologists have detected “erratic blocs” the size of three-story buildings, sliding downhill on earlier lava. “Under the top of the crater an ever-increasing lake of lava is forming, which sometimes overflows. This lava lake is breaking through the upper edges of the crater, and we think these blocks are proof of that. As long as the lava keeps them afloat, they will continue to move downhill,” explains the geologist.

Question. Why do volcanoes attract her?

Response. A volcano is the biggest visual stimulus I know. It makes you suddenly understand that the Earth is alive. It is a real manifestation that something is moving within you. It’s huge and impossible to control. There is no way to erase or cover. The only thing to do is walk away. It’s something that doesn’t happen often, like floods, fires and even earthquakes, which we’re more used to. As quiet as it is, a volcano is impactful.

FOR. What did you feel the first time you saw Cumbre Vieja erupt?

A. It was at night. I was breathless. The next thing was to think: where the lava is going down there are people, dwellings. And you get to work. In our case, this means giving the best possible advice to the authorities who need to manage the emergency.

FOR. Do politicians ask you many questions that you cannot answer?

A. Yes. The usual questions are: when will lava stop coming out and people will be able to go back to their normal lives. It is logical. The problem is that volcanology is not an exact science. There are many variables that we don’t control, and others that we don’t even know about. We know more and we have better instruments, but even so it is often impossible to know the result. We do emergency geology.

FOR. What portrait of this volcano does the IGME have in its hands?

A. Despite the enormous damage it is causing, we are facing a very normal eruption. It fits in with all the previous ones that took place in La Palma. It is a Strombolian eruption with explosive pulsations more or less violent, with lava emission. Everything looks a lot like what we know from chronicles written since the 15th century. The big difference is that we now have a much more populated island. The vulnerability is much greater because of this.

FOR. Do you think people are aware of this?

A. In the Canary Islands, the feeling is that people have very little historical memory of what an eruption is. The vast majority are not aware that they are active volcanic islands. When I arrived in Gran Canaria, I was told that there were no volcanoes anywhere. But the entire island is volcanic. All islands. This surprised me. The last terrestrial eruption was in La Palma in 1971, and on this island you find people saying that there have been no recent eruptions here. Only those who suffered them directly mention them. Sometimes these things need to happen so that people remember where they live. It is necessary to be aware of the risk that one assumes living here.

FOR. In recent days there have been strong earthquakes. How do you interpret them?

A. The volcano shows no signs of stopping tomorrow or later or in a week. The activity changes a lot each day, the cone builds first and then destroys itself. In recent days we are seeing deeper seismic activity again. This could mean a new entry of magma into the system. It may be reactivating, although this is something you have to wait to confirm with observation from the outside. My opinion is that it will continue to erupt for a while, we don’t know how much and we won’t be able to tell until the patterns of earthquakes and terrain deformation change. In some GPSs, we observed a stabilization of the deformation, but not a clear reduction. We depend on whether this new magma entry continues or stops.

FOR. Where does the magma that the volcano spews comes from?

A. With the data we have, it looks like there are three reservoirs. The deepest would be 30 kilometers underground. This is where the material could be merging, and it’s the main storehouse. There is another intermediate, 10 kilometers away, and the most superficial would be at about 4 kilometers. Magma can pass from one to the other or go straight from the deepest to the surface. This is what we think given the thousands of earthquakes recorded at different depths from 2017 until now, and the type of lava that is coming out.

FOR. As long as these reservoirs don’t empty, won’t the eruption end?

A. It’s not a matter of emptying themselves, but rather that the magma has enough strength to keep coming out. This depends on the gases. Magma has minerals, rocks and gases. The gas is dissolved in the magma. As it goes up, it separates. It’s like a Coke bottle. If it’s closed, it’s just a liquid. But if you shake it and open it, it becomes an explosion, because the gas bubbles have separated from the liquid. If they have a lot of gas, the bubbles make the lava more explosive. When the magma can no longer rise, it will stay there.

FOR. One of the most surprising things about the volcano is its roar. Why does this happen?

A. It’s like the volcano chokes. The gas exits through the main cone conduit at the top. The lava comes out of inferior mouths, very fluid. The sound we hear is magma outgassing. Every time this happens, pyroclasts come out with a lot of violence. Some fall within a kilometer or two of the crater, but others fall back into the crater and obstruct it. Each time this gas comes out again, it has to push the plug, and this produces the tremendous explosions and the rain of pyroclasts. When the volcano sounds like a bellows, it is by degassing.

FOR. What would happen to us if we were on the edge of the volcano’s crater?

A. You would be volatilized. It’s like a car bomb: do you die from the explosion, the shrapnel or the blow? It’s impossible to know. Here, the same thing happens with the poisonous gases, the extremely high temperatures and the constant bombardment of pyroclasts. If you’re there, it’s over.

FOR. Volcanoes can create tremendous destruction, but they are also the engines of life.

A. A volcano is a catastrophe, but also an opportunity. It can cause a lot of loss of human and material life, but, over the years, it becomes an opportunity, because the ashes of the volcanoes make the fields very fertile. In fact, they are used as an agricultural fertilizer. In addition, it is a tourist resource of the first magnitude, yes, for a long time to come. Volcanic terrains are like this: catastrophic in the short term and, after time, promising.

FOR. When can we climb to the crater when the eruption ends?

A. It could take years. If you go down to the Teneguía crater and put your hand on the ground, it’s still hot, and it’s been 50 years. The priority now is not to climb the volcano, but to recover what was destroyed and the people who lost their homes.

FOR.And how long will it take before the lava tongues can be removed?

A. It depends on the material that comes out, how many tongues it accumulates and its thickness. The interior of the tongue maintains a lot of heat, especially in the area close to the crater. It also depends on the volcanic tubes that form inside. You need to analyze and decide which zones you can access and which ones you can’t. Which roads are recoverable, and which new ones will need to be made.

FOR. Is it a mistake to build as it was built in La Palma?

A. Once that happens it’s easy to talk. What we should do is take volcanic processes into account in territorial planning. This is currently done, but 50 years ago it hadn’t been done. Neither here nor anywhere. Because where should we have banned building? Across the southern part of the island, what is the active zone? It is very complicated. We shouldn’t think too much about whether it was a mistake. There was probably no other option. The important thing is what to do from now on. Analyze which zones should not be built due to past eruptions and avoid these zones. You have to start over and take the risk of living on a volcanic island. This is not like a river that has a floodplain. We don’t know where the next volcano will come out.

FOR. Will something positive come out of this eruption?

A. Now it’s very hard to see. Affected people just want to go back to their homes. A flood passes and you can go back to your house, clean it up, get it back. But when a tongue of lava passes over you, there is no land, no home, no place to return to. To people who have lost everything, you can’t say that anything good will come out of it. What good is a property covered in lava? Houses were volatilized. They burn and disappear. The only good thing that can happen now is for the eruption to stop. The most important thing is that you don’t forget the risk of living on a volcanic island. May we all learn to live with volcanoes. We cannot do without them, nor can we leave. You have to take the risk. And, in time, good things will come out of all this.

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