La Palma eruption
The two existing streams run parallel, although without merging, while the platform is already 540 meters into the sea
Weather conditions complicate the situation on the island of La Palma. The process of thermal inversion (stability in the lower layers of the atmosphere and poor air circulation) in recent days is now joined by the Saharan advection phenomenon, which is a horizontal displacement of a mass of warm air laden with dust from the desert.
The director of the Volcanic Emergency Plan of the Canary Islands (Pevolca), Miguel Ángel Morcuende, explained this Saturday that, at the moment, air masses with different densities converge on the island of La Palma that have formed a layer of thermal inversion at about 600 meters of altitude, which constitutes “a kind of cover” for the gases emitted by the volcano and the lava delta into the ocean.
To this screen effect of the thermal inversion, it must be added that the prevailing trade wind during the last week has decreased considerably in intensity and at night it gives way to a sea breeze that blows inland. To make matters worse, the Saharan advection phenomenon has led to an increase in temperatures, which has forced the activation of the fire alert. The use of fire in agricultural and livestock activities has been prohibited, all recreational areas and the trail network have been closed to the public, and access to forest trails has been restricted.
With this outlook, Pevolca had to order the confinement of 3,500 residents from various neighborhoods in Los Llanos de Aridane and El Paso on Friday night. The reason was that the laundry burned some greenhouses and, with them, the fertilizers that the farmers kept in the tool rooms to fertilize the banana trees. “This produced a smoke that is obviously polluting and that does not find the possibility of diffusing because it runs into that cover of the thermal inversion layer,” Morcuende explained.
Although he warned that the situation on Friday could be repeated, the person in charge of the emergency plan announced yesterday the end of the confinements, which affected 8,000 residents of the Aridane Valley. «This level of contamination is not excessive. It can cause itchy eyes or minor bronchial discomfort, but is exacerbated in people with weakened immune systems, the elderly, pregnant women or children. We are not going to confine, but to notify by public address. If it is repeated, we will ask that they enter their houses and close doors and windows, “added Morcuende, who took the opportunity to thank the population for the” degree of civility “in this crisis caused by the volcano.
However, sulfur dioxide emissions from the lava-formed delta into the sea remain relatively high. The plume emits 2,330 tons of this gas per day into the atmosphere. Although the indices fell considerably compared to Thursday in all the measurement stations of the valley, the values in the whole of the island continue to be high. “In addition to the particles from the eruption, the intrusion of sub-Saharan dust is now added,” said Carmen López, the national head of volcanic surveillance at the National Geographic Institute.
The constant deposit of lava in the sea continues to produce clouds of water vapor and hydrochloric acid that are concentrated in a small area. López, who yesterday acted as spokesman for the Pevolca scientific committee, specified that the marine plume “should not be underestimated, but neither should it cause alarm.” According to the experts, “you have to pay attention to the wind forecast and act accordingly.”
The fajana, which is the platform created by the arrival of lava into the sea, has already entered 540 meters into the Atlantic and has reached a depth of 35 meters. Its progress is already slower, since each time it has to fill a larger glass of water (the slope is around 5%), although it approaches the slope, which is located one kilometer from the coast. There you will reach the height of 100 meters and you will find a 12% unevenness. The delta already measures 27.7 hectares and is widening at the base.
As for the volcano, the fissure eruption continues active, with explosive and effusive phases or with simultaneous activity. The national responsible for volcanic surveillance explained that the new stream has run west, parallel to the original, which is the one that flowed into the sea. Although they have established contact at some point, they have not merged, but run parallel to the coast.
López explained that at the moment there are several active centers in the main crater and two more in the northwest side of the cone. “The appearance of more mouths is not ruled out,” he pointed out. In fact, around 9 am yesterday a new emission center was detected, a “spillway” that for now only expels smoke and ash. The column of gases from the volcano reached a height of 4,500 meters yesterday.
The seismic activity is located, according to the expert, in the same areas as the previous days. In the last 24 hours, “a few dozen” earthquakes – the most important, of magnitude 3.6 on the Richter Scale – have been recorded at a depth of between 10 and 15 kilometers, although occasionally they exceed 20 kilometers. López warned that these tremors can cause small landslides in sloping areas.
The latest balance of buildings affected by the eruption is 1,005, according to the European Copernicus system. Of these, 880 have been completely washed away by lava and another 125 are damaged or at risk of being destroyed. There are also 28.3 kilometers of unused road network.
In addition, this Saturday the laundry destroyed the last irrigation connection, which is in El Remo, which caused a column of white smoke due to the lava coming into contact with the water. This will prevent farmers in the area from watering their plantations to maintain the banana trees, which is coupled with the loss of the harvest due to the rain of ash falling on the fruits, which has spoiled their appearance and prevents them from being marketed.