Submarine Eruptions off El Hierro Canary Islands
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Submarine Eruptions off El Hierro, Canary Islands

October 31, 2011
More than two weeks after the eruption of a submarine volcano off El Hierro, Canary Islands, the Atlantic Ocean south of La Restinga village was colored milky green from a volcanic plume rising from a vent on the ocean floor and carried by currents far south of the island. The Moderate Resolution Imaging Spectroradiometer (MODIS) flew over the region and captured this true-color image on October 26, 2011. The plume is likely a mix of volcanic gases and a blend of crushed pumice and seafloor rock.

In this image, a tan discoloration can be seen in midst of the green plume off the southeast coast of El Hierro island. This area has been judged as the likely center of the eruption, due to the intense discoloration and from the observation of a helicopter flight on October 15, which reported steamy lava fragments in this area, as well as the observation of large turbulent rings of gas and foam on the sea surface from October 15-17.

Beginning in July, tremors were reported from seismic stations on El Hierro. The tremors eventually intensified in strength and frequency. During the week of October 4-11 alone, the Instituto Geográfico Nacional (IGN) reported more than 700 new seismic events. On October 8, a 4.3 earthquake was detected, followed by low-magnitude seismic events. On October 10, volcanic tremor was recorded on all the stations on the island, strongly suggesting a submarine volcanic eruption. By October 11, the Government of the Canary Island evacuated the residents of Restinga Village, at the southernmost tip of Hierro, and declared a maritime exclusion zone about 4 nautical miles from the village.

Since July, there have been over 10,000 seismic events, most of them imperceptible to residents, reported from the stations at El Hierro. Volcanologists expect additional eruptions, and suggest that the volcanic activity will not be over anytime very soon. Despite the ongoing tremors, the residents of La Restinga have been permitted to return home.

Credits: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC

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