The volcanic eruption off El Hierro, as photographed by NASA
In July 2011, volcanic tremors began on the island of El Hierro in the Canary Islands. By September, many tourists evacuated the resort island, fearing a volcanic eruption. In early October, an underwater volcanic vent began erupting, sending ash and chemicals into the sea and causing muddy discolouration of the waters south of the island. Reports from a recent underwater survey by a Spanish research vessel revealed the presence of an eruptive vent and crater about 500 feet (150 metres) below the surface, accompanied by submarine 'pillow' lavas – pillow-shaped lavas that form underwater. The vent location was marked by brownish discolouration off the south tip of the island. Currents diluted and dispersed the volcanic material to the south and west.