It’s been less than a week since this started seismic crisis, until it finally came to an end with the volcanic phenomenon on the island of La Palma, off the northwest coast of Africa. As it has been remembered in recent days, the archipelago of the Canary Islands is of volcanic origin, and activity is still alive under its islands. Therefore, it is normal to expect its inhabitants Live an eruption like today on a regular basis.
Why was the explosion expected?
On September 11, a series of earthquakes began in the southwest of the island of La Palma. Scientists linked this to the possibility of magma pushing the surface, which could end up being the case It causes a rash. This is amazing swarm Earthquakes, as this temporary concentration of small earthquakes in one region is called, was getting closer and closer to the surface. The impacts have previously been recorded at a depth of 20 kilometers, and have begun to be observed at an altitude of about 100 meters in the past two days. With this behavior of the phenomenon, it was suspected that magma generates rips on its way to the outside world. Plus, the island swelled up to 6 inches this morning, another sign of magma.
Why did that happen now?
In October 1971, 50 years ago, there was the last volcanic eruption in La Palma Teneguía volcano, which was also the last volcanic eruption in Spain. Since then, seismic volcanic activity has been quiet. Until the reactivation occurred in 2017, with many swarms Seismic in subsequent years, but not as active as this week. All this explanatory power, along with the sudden deformation of the terrain, heralded the eruption.
How many earthquakes preceded the explosion?
According to the National Geographic Institute (IGN), in this swarm Seismicity, nearly 7,000 tremors, of low magnitude and intensity, could have been recorded as of Sunday morning. The current earthquake phenomenon is “very active”. In just a few days, it released more energy than caused El Hierro’s underwater eruption in 2011 over the course of two months, explained IGN Director in the Canary Islands, Maria José Blanco.
Why did this happen in this area?
The island of La Palma is geologically very young, only about two million years old – although it began forming under the sea four million years ago. But the island consists of two distinctly distinct parts: the northern, and the oldest, and most solid part; And the south, younger and still in composition. Magma continues to expand the island in the southern part. In fact, everything Volcanoes that appeared in recent centuries Occurred in this region, such as San Juan, in 1949, and Tinguya.
Why is there not a single volcano?
Eruptions in the Canary Islands are usually fissures, that is, they erupt in the form of fissures with various points through which lava, gases and other substances are emitted. David Calvo, of the Volcanic Institute of the Canary Islands (Involcan), explains that these eruptions occur in clusters. “We’ve counted eight so far, but more may emerge in the next few hours, while others fade away,” he says. The normal thing is the appearance of more agitated mouths, generally lined up. But when they enter a Maturity stage of eruption, some of these fissures will lose energy and will be covered up, concentrating all the power of the lava emanation at one point. “This is what happened with Teneguía, who at first opened several agitated mouths and then focused on only one, even covering the others,” Calvo says. Something similar also happened in the underwater eruption Iron, where measurements and submersibles can show a row with at least three cones from which material emanates.
Why did scientists know that a volcanic eruption would occur at this point?
The scientific community has installed several stations on the site for years, from organizations such as IGN, the Institute of Geology and Mining (IGME), Universities of the Canary, and Involcan. All these means allowed to completely locate the phenomenon, which focused on this point: both swarm Like deformation of terrain. Plus, in recent days, a team has mobilized more scientists, tools, and devices. The deformation of the terrain was calculated, for example, thanks to fixed stations, but also thanks to observations made by the Copernicus program with the satellites of the European Union. On the other hand, a plane requested by the Government of the Canary Islands to the Ministry of Ecological Transition of Spain traveled to the area to monitor volcanic activity. IGME sent out drones, and the Involcan helicopter was studying the tremors.
How long can the rash last?
It is not possible to know for sure. The historical background and volcanology of the area indicate that the volcanic phenomenon can last for several days, up to weeks, as happened with the recent volcanoes of Tagoro, El Hierro and Tinguya. However, it is too soon to know the dynamics of this eruption, the energy that the various fissures in the earth can release, and the number of cubic meters of magma pressing outward at the surface.
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