Well, we've been wondering when we might see more signs of magma rising underneath El Hierro in the Canary Island and now we seem to have got some. Over the last month, the island/volcano has experienced thousands of earthquakes that have waxed and waned in number, but seem to be increasing over time. A GPS survey of the area effected by the earthquakes has now found deformation - namely inflation - over part of the volcano. This inflation is on the order of ~1 cm over the last 20-25 days according to the Instituto Volcanologico de Canarias. There are also slightly increased carbon dioxide and temperature (above background) at the volcano as well. All of these signs add to up new magma rising in the volcano - so the big question becomes "does this mean an eruption is around the corner?" Well, my answer to that is a resounding "maybe". Sure, these are all signs of magma emplacement, but there is likely as much chance of it all "stalling" in the crust as an eruption occurring. It will be how these factors - earthquakes, deformation, gas emissions, temperature - change over the next weeks to months that will give us a better idea of whether we will see the first documented eruption at El Hierro since 550 B.C. (or 1793 A.D., depends on if you trust the historical reports from the late 18th century).
{Special thanks to @teideano for this data from the IVC}.
Top left: An undated satellite image of El Hierro. In the larger version, you can clearly see many of the small scoria cones and craters that pockmark the island.
