the essential For 29 days, the Cumbre Vieja volcano has been erupting. Thousands of homes have been evacuated, hundreds of hectares have been destroyed, and yet there is no indication that the volcano is weakening.
The transport around the island has become perilous, the airlines are undermined, with already 29 flights canceled. The phenomenon, mixing lava, volcanic lightning and toxic gas, is followed with attention. However, it shows “no sign of slowing down” affirms Ludovic Leduc, volcanologist at Objectif Volcans.
However, an index allows us to determine, approximately, the foreseeable duration of the phenomenon: the eruptions which occurred during the preceding centuries. “The eruptions of Cumbre Vieja in recent centuries could range from three weeks to three months, explains Ludovic Leduc. In detail, the previous eruptions of the volcano showed a certain descending continuity, with a duration of 84 days in 1585, then from 38 days in 1949, and finally of 25 days in 1971. So we can imagine that the current eruption will last that long, after nothing is not insured, it may be longer. ” With 25 days, it has in any case already exceeded the eruption of 1971.
The case of Cumbre Vieja is not, however, unprecedented. “The eruption in Iceland which started at the beginning of the year lasted six months, although it seems at the moment to be on the end” compares the volcanologist.
Magma, gas, what are the indicators?
“What typically happens with this type of eruption is that we see decreasing quantities of gas, a decreasing flow rate and today this is not the case” explains Ludovic Leduc. The amount of magma coming out of the volcano alone would not be a reliable indicator, despite the variations.
Indeed, it often happens that the cone closes, preventing part of the lava from coming out. “What happened several times during this eruption is that as the lava rises inside the eruptive mouth, it manages to have enough strength to dismantle one side of the cone, which reopens and allows the lava to come out, which generates new abundant flows “details the volcanologist, who ensures that flows which do not advance very quickly do not necessarily mean a general weakening.
“What we are looking at is the amount of gas, sulfur dioxide in particular,” he says. However, the latest measurements taken by professionals do not indicate any particular weakening. Regarding Cumbre Vieja, the lava flows still seem intense, as shown in a video of the volcano published by the Csic (the Spanish “Superior Council of Scientific Research”) on Monday 18 October.
El volcán de #LaPalma sigue con una intensa actividad estromboliana con proyección de piroclastos y generando un abundante flujo de lava that discurs in dirección al mar. Estas imágenes, del investigador Manuel Nogales, del @IPNA_CSIC, muestran la actividad del volcán ayer. pic.twitter.com/jUHPze3L3N
— CSIC (@CSIC) October 18, 2021