TW –
A strong earthquake swarm started under Cumbre Vieja volcano, La Palma, Canary Islands at 03:18 UTC on September 11, 2021.
From the beginning of the seismic series until 08:00 UTC on September 13, a total of 1 570 earthquakes have been detected, of which 354 were located. 315 earthquakes have been detected (90 located) to 17:45 UTC on September 12.
The magnitude of earthquakes have been increasing in recent hours, with a maximum magnitude of 3.4 mbLg.
The depth of the earthquakes remains between 8 and 13 km (5 – 8 miles).
Since October 2017 there have been 10 seismic series with similar characteristics in this area of the island of La Palma.
“The occurrence of events of this type in an active volcanic zone is within normality and does not present any risk to the population,” the Spanish National Geographic Institute (IGN) said.1
Only 15 earthquakes (M0.9 – 2.6) have been detected on the island during the entire month of August. 10 of these earthquakes have been part of a small seismic series that occurred on August 27 and 28 located in the south of the island.
Shallow depths suggest that new magma is currently intruding into a reservoir under the volcano, volcanologist Dr. Tom Pfeiffer said.2
“Whether or not this might be leading up to new volcanic activity is impossible to say at this stage, as there seem not to be other signs of significant volcanic unrest at this stage.”
Earthquakes registered in the previous two earthquake swarms under the volcano — December 20203 and February 20214, were deeper (20 – 30 km / 12 – 18 miles, and 15 – 20 km / 9 – 12 miles, respectively), which could indicate that magma has now risen higher in the volcano’s underground storage systems.
“Without a doubt, the current seismic swarm represents a significant change in the activity of the volcano and is related to a process of magmatic intrusion beneath La Palma Island,” the Volcanology Institute of the Canaries (INVOLCAN) said.