He Tenerife fire, which began on August 15, is presenting reactivations that place it again at level 2 of Infoca. Currently, the work is concentrated in three sectors located in the municipalities of Santa Úrsula, El Sauzal and La Orotava.
The teams that fight against these reproductions in the heat of the heat wave these days face a “underground” fire, a situation that is aggravated by high temperatures, low humidity and prevailing wind, which are the meteorological and environmental conditions that have been occurring in the archipelago since the beginning of October.
During this fire extinguishing process that has lasted almost two months, many reactivations have occurred below the ground, but the current conditions; Temperatures of more than 30 degrees, humidity less than 10% and the blow of the descending wind have been drying everything around, generating more hot spots. In statements to the media by Pedro Martínez, head of the Cabildo’s Forest Management technical service, the subsoil fire “burns slowly and is evident when it comes into contact with the air.” Trees with thick stems or their roots burn on the inside “until they start to burn on the outside or fall.”
How is the subsoil burned?
There are three main ways in which fire can advance and progress; the crown fire, which advances between trees close to each other; surface fire, which is spread by fuel above ground, such as pine needles, leaf litter, grasses, bushes or fallen wood; and soil and subsoil fire, the most difficult to detect, since it burns roots and other organic matter. Due to the low amount of oxygen, it hardly causes flames, which further complicates extinguishing efforts.
To produce combustion, it needs oxygen and it is found underground because the subsoil is not a completely airtight surface. A surface fire can find a stump, that is, a door, through which it can spread underground through the roots of trees. Forestry technicians consulted by this newspaper assure that this type of fire is the most difficult to predict, because in an environment where they are trying to extinguish the flames, it is difficult to detect the areas where it is occurring.
“The rains expected for next week could be good news”, rains that, if “they are good”, would penetrate to cool these surfaces and reach where the teams, even if they wanted to, cannot reach due to the orography of the terrain.
