Volcano eruption in the Canaries: how do you monitor a volcano?

Four techniques exist today to monitor the evolution of a volcanic eruption. The first and most important is the evolution of seismic activity. “In general, volcanic earthquakes are rarely felt, they are of low magnitude” informs Ludovic Leduc, volcanologist for Objectif Volcans. However, this activity is not immune to seismometers. Before an eruption, movements of magma create seismicity, and it is from the moment when it is linked and repeated daily that a risk of eruption is noted. According to the volcanologist, it is “what happens in depth that creates the seismicity, that is to say that we do not feel it when walking on the volcano”.

The second way to spot a potential eruption is in the deformation of the ground. This moves when the magma rises to the surface. “In La Palma for example, since 2017 there have been a few seismic swarms at 30 kilometers, so we were far from the eruption, then the last one was took place on 11 September, at 12 kilometers deep, the probability of an eruption was therefore greater “.

Finally, two other techniques exist. The first, gas tracking. As the magma rises, it loses gas, which can be spotted. “For example at great depth, it is carbon dioxide, then sulfur when it approaches the surface”, explains Ludovic Leduc. Finally, the activity of a volcano can be noted by satellite. A method which is used in particular for volcanoes located in uninhabited places. “In the desert for example, a large amount of infrared is noted by the satellite, therefore a high temperature, which shows a probable eruption” concludes the specialist.