The National Geographic Institute (IGN) has located this Thursday afternoon a earthquake of 2.9 in the municipality of Villa de Mazo (The Palm).
This earthquake was recorded at 7:21 p.m. at a depth of 28 kilometers.
Minutes before there was an earthquake of 2.1 in Fuencaliente, and another two of magnitude 2 in Mazo and Fuencaliente.
IGN sources consulted by Efe state that after the volcanic eruption in Cumbre Vieja ended, more than three months ago, there have been earthquakes of greater magnitude than 2.9, although they were in the first days after the volcano stopped roaring. .
The IGN teams are “attentive” to this “rebound” in seismic activitysince between ten and twelve have been counted in a short period of time, some of very low magnitude that do not appear in the automatic system.
In any case, the sources consulted by Efe indicate that already during this posteruptive process there have been similar seismic swarms.
“The normal thing is that there are peaks of activity for some time,” they warn from the IGN.
The catastrophic collapse that wasn’t
On the other hand, the fissure system that opened during the last phase of the eruption of the Cumbre Vieja volcano (La Palma) could explain why a catastrophic collapse of the volcano’s flank did not occur “as perhaps expected,” according to volcanologist Pablo González.
In an analysis published in Science, González estimates that a detailed study of the eruption should contribute to answering the open question of what physical mechanism triggers giant catastrophic landslides on the flanks of volcanoes.
The answer “it may be linked to its distinctive volcano-tectonic features and, in particular, to an unexpected fissure system that opened during the last phase of the eruption& rdquor ;, considers the expert.
Progress has been made since the 1980s, but the mechanisms that trigger sidewall collapse and feedback with active magmatic systems “remain elusive.”
The scientist points out that, “As if it were a great suspense movie, this eruption of Cumbre Vieja left the biggest surprise for its last act”.
In mid to late November, coinciding with an increase in the number of earthquakes, a complex set of fractures and detachments ruptured the northeast flank of the active cone, which had been developing for two months at the site of the eruption.
almost simultaneously, short-lived vents opened in an east-west direction down two kilometers from the active cone of the summit.
The following week, multiple small vents and fissures appeared within 1-3 km of the main fissure site, among other areas.
These volcano-tectonic structural changes must “be critically evaluated to determine if they released magmatic and/or gravitational stresses on the flank of the volcano.”
González believes that “it is still too early to offer a complete set of interpretations for all the volcano-tectonic observations of the Cumbre Vieja eruption.”
However, he estimates that the exploration of the complex volcano-tectonic tension fields should be “a possible way to understand the moment, the occurrence and the character of this eruption & rdquor ;.
In addition, volcanotectonic control will contribute, “without a doubt, to advancing our knowledge of the elusive magmatic and tectonic feedbacks that influence eruptive activity.”
For the expert it will be “especially revealing & rdquor; the sequence of events that caused a catastrophic collapse not to occur, as it should give clues on how to assess the probability of these for other systems.