More than 700 earthquakes deform the surface of La Palma and predict an eruption

The number of earthquakes located since last Saturday around the Cumbre Vieja volcano (La Palma), within the framework of the largest seismic swarm in recent years, has risen to 700, according to information collected by the National Geographic Institute (IGN). Furthermore, these tremors have caused a surface deformation of the island of around one and a half centimeters, which, however, still does not represent any risk to the population, but does denote a significant increase in activity in the area, as acknowledged yesterday , in statements to DIARIO DE AVISOS, the director of the Surveillance Area of ​​the Volcanological Institute of the Canary Islands (Involcan), Luca D’Auria, who does not rule out an eruption, although he is cautious about the deadlines that are handled.

Asked about the possibility that the palm trees will relive what happened in 1971, when the last volcanic eruption in Spain -the Teneguía- took place on the Isla Bonita, the expert indicates that, considering this antecedent, that it developed, at least Since the earthquakes were perceived by the residents, in “a few days”, the idea that the same thing happens cannot be dismissed. But, thanks to the measurement instruments of the Canary Islands Seismic Network, which have made it possible to know the exact coordinates in which each of the events is located, the pertinent protocols can now be activated with the necessary margin to avoid greater evils; “There is enough reaction time,” he emphasizes.

In addition, on the other hand, there is the fact that it is not a “linear” phenomenon and its evolution can vary very easily. In this sense, D’Auria explains that we are facing a “magmatic intrusion”, which means that the magma is moving and, in its wake, leaves shocks like those that citizens of several of the municipalities have already felt. They are on alert: Los Llanos de Aridane, El Paso, Fuencaliente and Mazo. “The magma is looking for a way out,” he says. However, not necessarily abroad. It has been moving from lower levels, which from 2017 to the middle of this year were between 20 and 30 kilometers deep, to the 10 kilometers on average in which it is currently located. In doing so, it also makes its way, removing everything it finds, causing the aforementioned surface deformations, which can be seen in a fork that is still “low”.

From this moment, he continues, two scenarios are projected. The first one is that the fluid reaches an accumulation zone or magmatic chamber -the latter, a term used for large amounts of material-, where it would go to a state of rest, which “is what happens normally”. But it is also expected that it will continue its journey to the surface and erupt. An assumption that is on the table and that, remember, should not generate social alarm, to the extent that 50 years ago, with the Teneguía, there were no scientific instruments, and the studies on the episode that have been carried out take as reference experiential accounts of people who lived in the surroundings. In 2021, the onset of earthquakes is monitored to the millisecond. In fact, the volcanologist assures that “it is the first time that a possible eruption on La Palma has been observed in such detail”.

In the last hours, seismic events have gained notoriety in the west of the island and, specifically, on the coast of Los Llanos and Tazacorte, covering an area that includes the neighborhoods of El Remo, Puerto Naos and Los Guirres beach. . Although, undoubtedly, the largest of them, at the close of this edition, is the one that was located at seven in the morning yesterday in El Paso, which reached magnitude 3.5 and became a topic of conversation during the morning coffees Not in vain were several neighbors who said they had experienced a shock.

HISTORICAL

“After the Teneguía eruption, the island of La Palma was silent, until 2017.” This is how Luca D’Auria went back to the genesis of this – for now – seismic crisis. From that year onwards, only three swarms were registered, until September of last year, when the geochemical monitoring of Involcan showed the highest levels of helium-3 concentration in Cumbre Vieja in the last three decades. Since then everything has changed, because the expulsion of that gas marked a turning point in the evolution of the volcano and who knows if in its future.

Throughout the 12 months that have elapsed since that alarm symptom, the swarms have increased in number and intensity; there have been seven (including the current one), and each time shallower, or, in other words, closer to the surface. In fact, with the one that began on Saturday, which has been the most important on record and contained earthquakes with an average depth of approximately 12 kilometers, this figure decreased throughout the night, moving between 7 and 9.

ALERT LEVEL

In response to the earthquakes, the Government of the Canary Islands activated on Monday the specific plan for volcanic eventualities, the Pevolca, determining that the four municipalities affected by the event would pass the so-called yellow warning traffic light. A purely preventive status, to refresh the emergency teams on the applicable protocols in these cases, and which reinforces the outreach work that Involcan is already developing regularly, with specific reports about the activity of the volcanoes of the Islands.

Asked whether the conditions exist so that, at the meeting to be held today at ten o’clock in the morning, the Scientific Committee formed for this purpose to evaluate the level designated for the Island, the expert of the The Institute points out that, in the late afternoon, there was no setting conducive to this, although it would be essential how events unfolded at night. In science there is always a margin of error, and when faced with a non-linear phenomenon, events can be precipitated.

AN EPISODE THREE TIMES FASTER THAN THAT OF EL HIERRO, BUT “DIFFERENT”

The director of the Involcan Surveillance Area, Luca D’Auria, avoids comparing the last swarm registered in Cumbre Vieja with the seismic events that shook the island of El Hierro in 2011, and that acquired so much social and media notoriety.

If analyzed out of context, the current swarm has developed three times faster than the El Herrera one. However, in the expert’s opinion they are two “different” volcanoes and, therefore, they must be analyzed separately. Moreover, it indicates that their behavior does not have to be similar, although it seems clear that on La Palma the terms used are usually shorter, taking as a point of reference what happened with the Teneguía.

Even so, he adopts a criterion of prudence and calls the population to calm down. He is confident that there will be enough room to prevent a possible eruption at Cumbre Vieja.

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