They are the eyes of geologists on the La Palma volcano. They fly over the cone and skirt of Cumbre Vieja to find cracks, bulges in the terrain, the flow of lava, the hottest spots or areas at risk of breakage. Last Friday, the intensity of the explosions alerted the scientific committee. The drones confirmed the suspicion. Two new emission centers had been opened from which a fluid and fast lava flowed that compromised the stability of the building, so it was decided to preventively evict three population centers (their neighbors have been able to return to their homes this Sunday after the disappearance of that instability). The unmanned aircraft also captured the displacement of large blocks and the breaking of the cone in the southwest sector on Saturday. The volcano had changed its appearance and had adopted a horseshoe shape on one of its sides.
The surface of La Palma already showed signs of volcanic reactivation in 2010
“It is useful for everything. Without drones, decision-making would be very, very difficult,” sums up Carlos Lorenzo, a geologist at the Geological and Mining Institute of Spain (IGME) and the Higher Center for Scientific Research (CSIC). He is one of the people in charge of flying the devices that record aerial images of the volcano. Juana María Medina, technical services assistant of the Emergency and Rescue Group (GES) of the Government of the Canary Islands, works alongside him. The regional administration has one of the most advanced drone models, the Matrice 210, which provides valuable information to the scientific committee, as it incorporates a thermal camera that detects the areas where the most heat is concentrated, the hot spots. “Much has been exploited in the investigation of the evolution of lava and its temperature,” explains Medina. According to Lorenzo, they have been able to fly at a distance of between 150 and 200 meters from the magma emission center without “risking” too much the device, which is subjected to high temperatures and which will have to be revised when this crisis ends.
These units are constantly on the alert to fly the drones when the scientific committee needs data. Since the volcano erupted last Sunday, they have gone out about three times a day. IGME researchers are the ones who decide where to go, explains Medina. “We are taking turns, because we cannot coincide in the same area.” Most of the aircraft used (three from the GES and three from the IGME) have a flight autonomy of 20 minutes, although the most advanced model, from the Government of the Canary Islands, can stay in the air 45. The smallest have six batteries. The largest has three feeding sets. Captured images are immediately recorded on a computer. This Sunday they tried to get that signal directly to the Forward Command Post. They succeeded, although with some delay. “We are calibrating the bandwidth to be able to give that coverage,” he adds.
According to the conditions set by the State Aviation Safety Agency (AESA), the drone can only be flown, from the point where the operator is, at a maximum distance of 500 meters and a height of 120. However, under circumstances Like the current ones, this radius of action can be extended with the prior authorization of the area air coordinator. “To choose the location, we check that there is no electricity, neither low nor high voltage. Especially high voltage, it can create interferences. In addition, we are looking for flat places, where there is as little picon (lapilli) as possible. Yesterday we arrived at the foot of lava, in the church of Todoque (this Sunday collapsed), but nothing was flowing, “says the specialist in Emergencies.
Explosions, wind changes and the direction of expulsion of the pyroclastic material are other difficulties encountered in this work. “When the shock waves are generated, the smallest drones are also destabilized. There are times when you lose even the signal with the radio control and there you get scared because you think you have lost it. You always have it in your visual”, says the assistant GES technical services. “Ashes and pyroclasts are one thing, which the wind can help them, and another is the shape of the mouth itself, which can turn the other way. On Friday, for example, we were flying and there was a moment when it changed, there was a bigger explosion and the pyroclasts were coming on us. There were bombs of a certain size and they could be seen passing in front of the camera. If one had hit it, we would have lost the drone “, says geologist Carlos Lorenzo.
The GES and IGME drone units arrived on the island of La Palma on Friday before the eruption to study the deformations that were taking place on the surface of Cumbre Vieja. They were in the Jedey neighborhood and in several surrounding towns, georeferencing certain areas to see the evolution of the terrain. On Sunday they were working in the hermitage of Fatima. They heard the explosion and, “on the fly”, the drones flew. Yesterday they returned to that site. The orography of the area has changed substantially.
To date, the drones of the General Directorate of Security and Emergencies of the Government of the Canary Islands had been used in search support, in rescues, in forest fires … One of the last jobs of the drone with a thermal camera was in Arico, in Tenerife, in a fire that started in May and affected around 3,000 hectares. The unmanned aircraft flew over the area to check where the hot spots were located and thus facilitate the work of the Environment services and the extinction work.
“We look for the scientific takes”
For Carlos Lorenzo, drones provide a fundamental added value in this type of emergency. “We can measure certain things in the distal areas (further from the lava emission centers, but in the areas closest to the cone we are not being able to access more than with drones. With these images we can see details that are not visible from no other way. “The geologist highlights the fact that those who are flying the devices are not only drone specialists, but also geologists. cracks, where it is bulging, where a new crater is being covered. ”
These teams analyze what is happening in the upper part of the volcano and map the lower areas. “With the thermal camera, once the lava flow has flowed down the slope, we are seeing exactly which areas are the hottest and most likely to flow faster.” Lorenzo recalls that before the unmanned aircraft appeared, they reported “with what they could.” “In the past there were helicopters and we would get on the helicopters. But in an area like this, you couldn’t get the helicopters very close, you would have to go pulling zoom cameras. In the past, the only thing you could do were things from the distal parts, doing analysis. of what your laundry is doing … With the drones, we are arriving, without risking the drone much, about 150-200 meters from the emission zone “.
The drones broadcast live and the signal is stored in a computer. “If it were of necessary interest, the drone could even be sacrificed on purpose, but in principle it is not necessary. We are getting very good information without having to sacrifice one,” explains the geologist, who states that the prices of these devices are around 1,000 or 2,000 euros, although the most advanced equipment can cost up to 40,000 euros.