The Canary holiday island of La Palma has recorded dozens of mini-earthquakes over the weekend, scientists report.
More than 40 tremors were recorded in just 48 hours, all between 1.5 and 2.7 on the Richter scale, although they took place at such depth under the sea that residents on the island did not feel them.
It has raised fears the islands’ huge Cumbre Vieja volcano could erupt, which some scientists have warned could then collapse into the sea, causing a a mile-high tidal wave that would hit Spain, Britain and the east coast of the US – although leading experts describe this theory as ‘rubbish’.
Shaken: More than 40 tremours were recorded in just 48 hours, all between 1.5 and 2.7 on the Richter scale, by seismologists on La Palma in the Spanish Canary Islands
The controversial 2013 study by Dr Steven Ward, of the University of California, and Dr Simon Day, of the Benfield Greig Hazard Research Centre at University College London, claimed that if the Cumbre Vieja – an active but dormant volcano – were to erupt, the western flank of the mountain could tumble into the sea.
Writing in Geophysical Research Letters, they said a build-up of groundwater could destabilise a block of rock up to 500 cubic km in size, which could break off, smashing into the sea at up to 350 km an hour (220 mph).
This eruption could cause the landslide, which will unleash a deadly wall of water, initially almost 3,000ft high and several miles wide, to hurtle at speeds of up to 800 km an hour (500 mph).
However, experts have slammed the study as a ‘scare’.
‘This scare should be consigned to the garbage can once and for all,’ wrote Dave Petley in a post for the American Geophysical Union.
He said the phenomenon the researchers studied, known as a flank collapse, would only have generated small waves.
‘Previous flank collapses have occurred as a series of distinct events rather than as a single coherent block,’ he wrote.
‘Each of these could have been able to generate a very large wave, and even a local tsunami. However, they would not have generated a megatsunami.
‘There is no reason to believe that a future event will behave differently.’
Professor Iain Stewart the director of the Sustainable Earth Institute at Plymouth University, told Devon Live: ‘I’m not going to say it’s rubbish – but it hasn’t happened since the beginning of civilisation.
Rare: Such seismic activity is not usual on Palma but, experts say, not abnormal
‘The short answer is that it’s not happened in the last 10,000 years.
‘At the moment there is definitely nothing to be disturbed about.’
The largest of the tremors, which took place at 1pm on Saturday hit 2.7 on the Richter scale and was located at a depth of 17.4miles.
In the following hours, another ten tremors were recorded, taking the total of mini-earthquakes until Tuesday to 50, according to the National Geographic Institute (IGN).
La Palma is the most north-westerly island of the Canary Islands, and is home to some 86,000 people – a population which increases significantly during tourist season.
Like the other Canary Islands, La Palma is volcanic and is considered the most ‘active’ in the archipelago.
The most recent eruption on the island, which saw the Cumbre Vieja – ‘Old Summit’ – volcano erupt, took place in 1971.
The current event has been dubbed a ‘seismic swarm’, and while unusual, large numbers of these smaller tremours are not abnormal, the director of the IGN in the Canary Islands, María José Blanco, told Canarias7.
However, she added that they had ‘never recorded a similar swarm’ since monitoring began on La Palma.
The IGN and the Volcanological Institute of the Canary Islands (Involcan) have increased surveillance on the island to monitor the increase in seismic activity.
A spokesperson for Involcan told Canarias7 that ‘seismic swarms’ are ‘absolutely normal’ for an active volcano such as Cumbre Vieja.