In the early hours of Wednesday morning, between 4:00 and 7:00 UTC, the National Geographic Institute (IGN) detected an anomalous seismic swarm near Pico Viejo in Las Cañadas del Teide, with approximately 500 earthquakes recorded in just three hours. This marks the fifth such episode in the area since 2016. While the swarm is considered unusual, the director of IGN in the Canary Islands, Itahiza Domínguez, stressed that it is unrelated to the processes that triggered the volcanic eruption on La Palma in 2021.
Context and Observations
Domínguez explained that the event is not unprecedented, though its precise cause remains uncertain. “This is the fifth instance of similar activity since 2016,” he noted, adding that technological advancements now allow for detection of such events, which in the past likely went unnoticed due to the lack of monitoring tools.
The seismic swarm began with 10 small earthquakes, each with a magnitude below 1.1 mbLg, at depths of 8–12 kilometres. These were followed by high-frequency signals lacking defined seismic phases, culminating in hundreds of small, evenly spaced tremors. Unlike the 2021 La Palma eruption, these microseismic events were not felt by the population, as they are low in intensity.
Significance and Risk Assessment
Domínguez emphasised the need for vigilance, stating that while the swarm is linked to Tenerife’s inherent volcanic activity, it does not currently signal a heightened risk of eruption. “The worrying scenario would be if this occurred weekly,” he said, but assured that such activity is sporadic. He highlighted the challenges in analysing Tenerife’s volcanic behaviour due to the lack of instrumental records from historical eruptions, which were primarily documented through human observation.
The Volcanological Institute of the Canary Islands (Involcan) added further context, attributing the activity to a pressurisation of Tenerife’s volcanic-hydrothermal system, which has been ongoing since 2016. This pressurisation is thought to result from the injection of magmatic fluids into the underlying system. Involcan clarified that these events do not increase the short- or medium-term likelihood of a volcanic eruption.
Historical Perspective and Current Data
Since 2017, Tenerife has recorded at least 118 seismic swarms and five hybrid seismic events. Previous notable swarms occurred in October 2016, June 2019, and June and July 2022. The current event appears to follow the same pattern, lasting only a few hours and occurring in a region where earthquakes are annually recorded in a scattered manner.
Despite the ongoing seismic activity, Involcan estimates the probability of a volcanic eruption on Tenerife within the next 50 years at 39.35%. These figures underline Tenerife’s status as a volcanically active island, necessitating continuous monitoring and research.
The recent seismic swarm, while anomalous, serves as a reminder of the island’s dynamic geological nature. Scientists and authorities will continue to analyse the data to enhance understanding of the processes occurring beneath the surface of Teide and the broader volcanic system of Tenerife.
