More than 630 earthquakes of very low magnitude recorded rhythmically this Tuesday, southwest of Pico Viejo, in the Canyons of Teide (Tenerife)have led the canaries to wonder what is happening in the National Park and if that “beat of the drum” heralds a change in the dormant volcano.
Carmen López, director of the Central Geophysical Observatory of the National Geographic Institute (IGN), explains to the Canary Islands Now that this new seismic swarm “It is a recurring signal that reminds us that we live on a volcanically active island.” These microseisms, which have not been felt by the population, fall within the “normal”. “There is no parameter that worries, that is not the usual”, settles the expert.
This is not the first time such a swarm has been detected. In fact, a very similar episode was reported on June 17, also June 14, 2019 or October 2, 2016, as more recent dates. The first time similar earthquakes were found in Las Cañadas was in 1980, when the first microseismic study campaign was carried out, which shows that this type of activity is “recurring” and characteristic of this area.
As explained by the Volcanological Institute of the Canary Islands (Involcan), it is likely that the origin of the swarm is hydric, that is, it would correspond to movements of fluids such as steam, gas or water inside the hydrothermal system of the volcano. “This swarm does not imply a greater probability of an eruption,” they emphasize from the institute. Thus, continues the IGN, the analyzed activity indicates a readjustment of pressures in the lower part of the crust, due to the volcanic nature of the insular building and the magmatic processes in depth. “This type of activity is expected on active volcanic islands, and it may remain at that depth or may lead to shallower seismic activity in the future, without this pointing to an eruptive process,” they concluded in a statement.
The seismic swarm, which has occurred at almost regular intervals of time in the form of “drum beating (drum beat)”, has been detected thanks to the high-sensitivity technology used for this cause by the IGN, with its Canary Islands Seismic Network. These devices make it possible to prepare very precise reports that accurately locate the place and time when the earthquakes occurred.
Seismicity in the Güímar Valley
The Canary Islands Seismic Network of the National Geographic Institute (IGN) has also detected some earthquakes in the last 36 hours at the summit of the Güímar Valley. The largest magnitude, 2.0, took place this Monday, July 11, in the municipality of Arafo, at a depth of 13 kilometers.
Carmen López comments that in this area the background seismicity is characteristic and corresponds, to a large extent, to the seismicity of the volcano of In the middle, located at the bottom of the Atlantic, between Tenerife and Gran Canaria. In the words of the expert, “sometimes earthquakes are detected on land, in the Valley; others in the sea, between the islands”.
About this episode, within “normality”, there is no need to worry either.
The earthquakes that did alert the population
The Canary Islands closely follow the evolution of seismic swarms because they are one of the symptoms of a possible volcanic eruption. It happened in La Palma before the last and devastating volcano exploded in Cumbre Vieja. The island experienced strong seismic movements for weeks, felt by the population of the entire island, and at a shallow depth. This is precisely the difference with the swarms on Teide: the intensity does not correspond to a foreseeable volcanic eruption, as Itahiza Domínguez, a seismologist at IGN, explained to this newspaper during the June swarm. “All together they do not reach intensity 2”, he detailed, cooling down the possibility that the process experienced in La Palma could now take place in Tenerife. The eruption of Tagoro, the submarine volcano of El Hierro, in 2011 was also announced in this way.
Although most of the seismic movements detected in the Canary Islands go unnoticed by the population, throughout history some have been recorded that, due to their intensity, have alerted the public. Luckily, everyone has been left in a scare.
The most recent large-magnitude earthquake without being associated with a volcanic eruption was the one detected in the early morning of January 18, 2019. With an intensity of 4.2, the shock made the residents of Tenerife get up early, around 06:36. The movement was felt especially in the municipalities of the north, east and south of the island and lasted at least four seconds. The epicenter was located in the Atlantic Ocean, between the capital’s islands, in the so-called “volcano of In the middle”. It is worth remembering another earthquake with similar characteristics, of 4.1, in Tenerife at the beginning of February 2010.
Likewise, the strongest earthquake in the Canary Islands in recent times was felt at the beginning of May 1989, especially in Tenerife, with a magnitude of 5.2 and an epicenter located 15 kilometers from the Güímar coast. The tremor was noted at 02:30 in the morning and surprised the population sleeping. Luckily, it was just a scare: this tremor caused no damage.
On the other hand, in Gran Canaria, a magnitude 3 earthquake at the end of October 2003, produced on land and only five kilometers deep, shook the island, especially the central and northern municipalities.
No one can predict the moment when the next seismic swarm will occur or the next earthquake that puts the population on alert. However, no one rules out that these episodes will not be repeated on volcanically active islands.