Experts fine-tune the measurement of the parameters that put an end to the eruption of the La Palma volcano
The days are discounted for terminate the eruption of Cumbre Vieja on La Palma, and the scientific community increasingly fine-tunes the measurement of parameters to be able to say that the activity has concluded in the west of La Palma. The four legs on which this decision is based are seismicity, deformation of the ground, the presence of sulfur dioxide in the atmosphere and the volcanic tremor.. Since last Monday night, these indicators have reflected a positive balance and, if they continue like this, there would only be three days left for the long-awaited news of the end of the eruption to arrive after more than three months. Despite everything, the experts they keep asking the population for prudence, since it will not be possible to recover normality the day after declaring the volcano extinct.
During a visit yesterday to the wash located more to the north of the main building of Cumbre Vieja, the volcanologist of the National Geographic Institute (IGN), Stavros Meletlidis, commented that, during the current "waiting phase" in which the volcano is immersed, "There are aspects that can be measured that we could not before, such as the temperature at depth relatively close to the cone, or taking a sample of the gases from this last phase". For this reason, in recent days scientific personnel from the different agencies that make up the surveillance network of this process have been seen in the vicinity of the main crater, making new measurements, beyond the security strip of one kilometer around the building. volcanic. "Those fumaroles that are seen today, that degassing near the crater, will allow us to learn more about the volcano," insisted the expert.
As they have explained since Canary Islands Volcanic Emergency Plan (Pevolca) Once the apparent activity of the volcano has ceased, these days the values of the volcanic tremor are taken into account, the seismicity and the emission of gases remain stable. Not so the deformation of the terrain, which in the Jedey station, the closest to the emission centers, came to mark a deformation of eight centimeters during the day, although it has already been partially reversed. The measurement of these parameters is increasingly refined, since the calm that currently exists in the eruptive process allows them to get closer and measure issues that were previously impossible to measure.
Expert staff discover certain products and structures in the vicinity of the crater
«The parameters in a volcanic eruption in general must be seen in a context and as a whole. It is not a question of having them at a given moment, but rather that the data obtained must be collected as a whole and in a broader context in order to be able to identify these phases of which we are talking. This is what we have done from the beginning, and that is why we have been able to carry out the evacuations with resounding success, "defended Meletlidis. In addition, all this information that is being extracted from the volcano, and that will be so important for future eruptions in many other parts of the world, has been obtained without endangering, at any time, the lives of the scientific and emergency personnel deployed. on La Palma these weeks. «You have to take certain precautions, be respectful and not risk, because no scientific data is worth a human life »added the volcanologist.
Despite the intense rain that fell on La Palma yesterday, which left significant amounts of precipitation in many parts of the island's geography, the scientific community continued to exercise its surveillance work. Meletlidis himself made some temperature measurements on the ground, which continue to show that the washes remain hot, with Values up to 150 degrees Celsius at certain points. Hence they cannot relax. Still these washes cannot be stepped on, because, beyond the heat they give off, they also harbor other dangers, such as the gases emitted by the sleeping giant, or the possibility of collapse, which is more than possible. All this means that many precautions are taken when approaching them to study them and take the necessary measures.
In addition, the access roads to these areas closest to the volcano remain, in many places, practically impassable. In fact, on yesterday's visit, there were times when the off-road vehicles of the IGN and the GES had some trouble moving forward. The rain also contributed to this, making cars skid on the wet ash. If to this is added that the visibility conditions yesterday, in the middle of the downpour, were practically nil, the situation was very compromised.
Despite the completion of the eruption, the population will still have to wait to return home
In addition to refining the measurements aimed at declaring the end of the eruption, the scientific staff who approach the main building of Cumbre Vieja also manage to extract new knowledge. This is another of the great objectives of the surveillance network: it is not only a matter of supervising the progress of the volcano, but also of extracting information that allows us to know it more in depth and to be able to use this data in other eruptions that may occur at different points in the world. planet. According to Meletlidis, this greater proximity to the crater has the importance of the discovery of "certain products and certain structures" that the volcano generates only in the vicinity, such as dense volcanic bombs that can "give clues about the magma and the conditions in depth."
Likewise, during the eruption the IGN had installed a thermal camera within a radius of one kilometer around the main building of Cumbre Vieja, since this type of camera does not have the capacity to zoom. Even so, the data were not entirely reliable, but once the apparent activity of the volcano ceased, they have been able to install another of these thermal cameras even closer "to have a more direct and better view of those physical parameters of temperature inland from the crater itself, 'explained Stavros Meletlidis. All of it will contribute to having every aspect of this natural phenomenon well studied and analyzed, and contribute to its generalized and detailed knowledge, as never before has been done in an eruption of these characteristics.
Caution and patience
If the parameters continue in the current stability trend, within three days the Pevolca could formally declare the end of the eruption at Cumbre Vieja, which completed three months last Sunday. Despite this, both the scientific committee and the institutions themselves insist on informing the population that, nevertheless, this does not mean that they can return home immediately. Many of these people have been away from their homes for more than 12 weeks, so it is understandable that they want to return, but they will, said Meletlidis, "when the security conditions for this are guaranteed."
Yesterday, and for the second consecutive day, those who have their homes or farmland in Puerto Naos, La Bombilla, El Remo and other coastal towns of Los Llanos de Aridane they could not enter the exclusion zone because the presence of toxic gases was still high to the average in background levels. There are many dangers that, although the crater has stopped pouring out lava, can continue to occur in the area affected by the eruption. The examples specified by the IGN volcanologist were "episodes or moments where there can be seismic activity, formation changes or gas emissions", something that keeps the concern intact among the surveillance network of the phenomenon. In that sense, he insisted that people have to understand that, at this time, "Perhaps there may be houses that are not prepared to be inhabited, that may have structural damage from earthquakes or ash loading, or that may be close to a diffuse gas emission". The rains that have fallen in recent days can also have effects, since the lava flows have modified the topography of the Aridane valley, causing certain variations in runoff, displacing the water currents to points that are not prepared to absorb these. quantities.
«That calm creates a comfort zone for us, because we do not feel directly threatened, but it is not like that, there are still certain dangers such as collapse of streams, emission of gases, seismicity ... Do not relax because routine leads to mistakes, and we must always be attentive and listen and follow the recommendations of the Pevolca ", argued the expert. In this sense, he assured that everyone hopes that normality will gradually recover on the island, but he predicted "additional instructions that will have to be followed," for which he asked the evicted inhabitants for patience and prudence. «We as watchers of the volcano, as scientists, We have always felt the support of the people, they have always trusted our work, and I think that now they have to give one more example of that trust"Concluded Meletlidis.