Canary Islands Government Puzzled By El Hierro Earthquake Swarm

By Mark Dunphy

The Canary Islands Government says it has commenced an in-depth geological survey of El Hierro, the smallest of the islands, in an effort to determine the source of an earthquake swarm.

The unprecedented seismic activity commenced on 19 July. In excess of 6,000 earthquakes have been recorded up to 14 September 2011. More than two dozen tremors were recorded during Wednesday (14 Sept.) alone.

The vast majority of the tremors have been recorded in the northwest of the 278.5-square-kilometre island at El Golfo, the location of a massive landslide that created a 100-metre high tsunami almost 50,000 years ago. The earth tremors have ranged between 1 and 3 magnitude, the National Geographic Institute (IGN) reported.

However, the Volcanological Institute of the Canary Islands and Actualidad Volcánica de Canarias have both reported a sizeable decrease in the number of tremors recorded during the first two weeks of September, compared to the latter half of August.

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