Unusual series of earthquakes

The latest tremor (above, red star marks epicentre) occurred late at night on the first of November 2023, again near the island's capital San Sebastian de La Gomera and was of 2.5 magnitude.The other markers show where and how intensely it was felt by the population.  (Source: IGN)

There has been a series of minor earthquakes reported by the Spanish agency IGN (Instituto Geografico Nacional) in or very close to La Gomera , some of which were widely felt all over the island. Most were on the eastern side near the capital San Sebastian de La Gomera. This somewhat unusual event began last Saturday night and by Monday about 15 minor quakes up to magnitude 2.8 on the Richter scale had been reported by IGN. Some of these quakes were widely felt across the island with reports of the typical low rumbling noise that accompanies earth tremors also coming from various parts of the island. Even the director of the Canarian branch of IGN, Itahiza Dominguez, called these events ''un poco anomala'' ( a bit abnormal) when asked for an explanation by the press. She also said that since the installation of the latest seismograph in La Gomera in 2017 there had been only 17 earth tremors registered by said station previously.

More than that six year total has now occurred in the past few days. However, La Gomera has been volcanically 'dead and cold' i.e. inactive for more than a million years. As it is one of the oldest Canary Islands in origin, the latest activity is unusual and probably points to tectonic movements of some kind, according to Dominguez.

The depths of the epicentres initially were between 10 and 23 kms, but the latest quakes had their origin only 4 to 8 kilometres underground.

There's a rumour going around that the seismograph was triggered by undersea cable laying preparation works for the electricity inter-connector between Tenerife and La Gomera, which is to come ashore in the municipal area of San Sebastian de La Gomera, causing the rumble similar to those heard and felt across the island. It has also been known that very heavy swells at sea pounding La Gomera's coastline will cause the sensitive seismic station high in the mountains of La Gomera's Garajonay national park to register tremors, as do rock blasting operations and tunnelling for roads. However the scientists at IGN are no fools and usually are wise to these causes. They will not report those tremors  as earthquakes and won't list them in their bulletins. 

Overall, La Gomera remains one of the safest places in the Canary Islands in general and seismically in particular. Maybe the vibrations were caused by some blown-in minstrels blowing their didgeridoos too enthusiastically...