On October 23, 2011, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color view of El Hierro and the North Atlantic Ocean surrounding it. A milky green plume in the water stretches 25-30 kilometers at its widest and perhaps 100 kilometers long, from a large mass near the coast to thin tendrils as it spread outs to the southwest. The plume is likely a mix of volcanic gases and a blend of crushed pumice and seafloor rock.
Tremors were reported for the past several months from seismic stations on El Hierro, particularly in the northwest of the island. Then on October 12, 2011, the strength of the tremors significantly decreased while foaming, rock-strewn plumes appeared in the sea to the south of the island. The underwater plume of volcanic debris has persisted for nearly two weeks and has been mixed and dispersed by ocean surface currents. The eruption is occurring in water that is tens to a few hundred meters deep.
Geologist and blogger Erik Klimetti offered this analysis: “It looks like the main fissure might be 2-3 kilometers in length and is close to on strike with the rift axis for the main El Hierro edifice. Ramon Ortiz, coordinator of a government scientific team, said that if/when the eruption reaches shallower water, we should expect to see the surface water start to steam, followed by explosions of steam and magma and finally the emergence of an island.”
Irish Weather
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