Over the last few weeks, there has been a lot of buzz in the volcano world (at least in the internet) after some seismicity under El Hierro, one of the many volcanoes that make up the Canary Islands off the coast of Africa. The seismicity, although mostly of low magnitude (< M2), has been of high volume, with over 1,000 of this microquakes occurring since the swarm started in early July. Almost all the seismicity has been confined to depths of 9-16 km below the surface, which in a place like the Canary Islands, is close to/across the boundary of the lower crust and the upper mantle in an oceanic setting such as this. The question on everyone's mind is this: is El Hierro preparing for an eruption and, if not, what is going on underneath the volcano?
Young-looking pahoehoe lava from El Hierro in the Canary Islands
Before we ...
