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  • Magma mixing at the start of the eruption
    Magma mixing at the El Hierro submarine eruption
    The Spanish Instituto Geográfico Nacional (IGN) just published an interesting report "INFORME PETROLÓGICO DE LA ERUPCIÓN DE LA ISLA DE EL HIERRO" - a petrographic analysis of the juvenile magma erupted during the (ongoing) submarine eruption south of El Hierro Island: The report (in Spanish) is found at: www. ... more
  • Tremor decreased sharply last night
    The volcanic tremor decreased sharply last night after the previous post. A possibility is that part of the submarine vent has collapsed and might have blocked the flow of lava. ... more

El Hierro volcano (Canary Islands, Spain): increase in tremor and signs of a possible new submarine vent near La Restinga

Saturday Nov 19, 2011 20:21 PM | Age: 189 days

Increasing volcanic tremor (19 Nov), image courtesy IGN
Increasing volcanic tremor (19 Nov), image courtesy IGN
The new area of upwelling water, located ca. 300 m offshore (19 Nov)
The new area of upwelling water, located ca. 300 m offshore (19 Nov)
Zoom onto this area with flattened circular areas of the sea surface clearly visible (19 Nov)
Zoom onto this area with flattened circular areas of the sea surface clearly visible (19 Nov)
During our observations from near the south coast at La Restinga yesterday, we could not observe any activity at the surface of the water. This corresponded well with a sharp decrease in tremor measured by the Instituto Geográfico Nacional (IGN).
Today, we could see areas of the ocean surface flattened by likely upwelling water rising from below, at a much closer distance to the shore than the previously active vent area, at only about 300 m distance from shore and slightly to the east as compared to the former area. Volcanic tremor has increased significantly again. We suspect that a new vent might be forming or has formed in this area. Whether this leads to another "jacuzzi" or boiling water area is only speculation at this point. The situation remains interesting.
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El Hierro volcano (Canary Islands, Spain): intense volcanic tremor and speculations about possible new vents

Thursday Nov 17, 2011 19:48 PM | Age: 191 days

A brown spot is visible above the submarine vent.
A brown spot is visible above the submarine vent.
At times, upwelling water causes the surface of the water to cover with foam.
At times, upwelling water causes the surface of the water to cover with foam.
Dark strings of mud(?) floating in the area above the vent
Upwelling flattens the surface of the vents, but no steam or hot block were observed.
Upwelling flattens the surface of the vents, but no steam or hot block were observed.
Helicopter pictures of the upwelling muddy water above the vent published on 17 Nov by Guardia Civil – Involcan.
The volcanic tremor measured at El Hierro remains at very high levels and in sharp contrast to visible activity, feeding speculations and fear about new volcanic vents opening up somewhere on or near the island. Some fear such a new vent could be located in the El Golfo Bay, near Frontera, since most of the (deep) earthquakes in recent days are concentrated beneath the northern sector of the island. However, so far, these earthquakes are very deep (ca. 20 km) and do not point towards an immediate eruption in this area, rather are intrusions of dykes in the upper mantle beneath the island.
At La Restinga at the southern tip of the island, we could observe a slight increase in activity from the submarine vent ca. 1 km off the coast today: every 15-30 minutes, brownish plumes of water could be seen upwelling, flattening the ocean surface and somtimes producing dark stretches of floating mud(?) and foam (not steam!) in a circular area around the vents.
The Instituto Volcanológico de Canarias (INVOLCAN) has been recording highly elevated levels of Helium and CO2 gas dissolved in the water around La Restinga, another sign that the submarine eruption is still in progress.
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