Cumbre Vieja volcano (La Palma, Canary Islands): small earthquake swarms possibly indicating re-awakening of volcanic system
Sun, 15 Oct 2017, 22:4922:49 PM | BY: T
Recently, new seismic activity has started under the Cumbre Vieja volcano, which is the historical active volcano of the island (occupying its southern half). Two small earthquake swarms occurred during 8-9 and 13 Oct under the southern part of the island.
Earthquakes under La Palma Island during Oct 2017
The quakes were small, up to magnitudes of 2.9, and still relatively deep (15-30 km depth), but probably indicate that the magmatic system of the volcano has entered a phase of re-charging by deep magma intrusion at and under the base of the crust.
It is too early to say much about whether this is a precursor of new activity in a not-too-distant future (months to years), but certainly something that merits close monitoring.
Cumbre Vieja volcano is one of the most active in the Canaries and has had historical eruptions in 1585, 1646, 1712, 1949, and 1971.
As many ocean island volcanoes by nature, the La Palma Island is prone to catastrophic flank failure events. The flanks of accumulated rock masses become unstable over time and sometimes slide down into the ocean as giant landslides along large detachment faults, triggering potentially huge tsunamis.
While it it true that such events have occurred in the past on most of the Canary Islands, it is important to note that these events are rare and occurred at large time intervals spanning many tens of thousands of years.
It has often been speculated that La Palma's western flank is a good candidate for such an event in the future. Unfortunately, most media are driven by sensationalism and report about it as if there was strong evidence that such a partial collapse of La Palma could occur in the somewhat near future - including potential horror scenarios such as mega-tsunamis devastating the east coast of the US. Fortunately, there is no scientific evidence to support this picture. Like with other catastrophic events in nature (large asteroid impacts, super-volcano eruptions etc), they are first of all, extremely rare.
There is little to prevent them from happening, little to do against them, relatively little known about them, but from a pragmatic point of view, there is no reason to worry about them more than a 100 years ago, and currently no reason to believe we're in for one in the foreseeable future.