Update on the eruption in El Hierro volcano on 9 November, 2011

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The eruption in El Hierro volcano is ongoing and does not appear to show any signs of ending. However the strength of the eruption has dropped a bit during the past two days. But this was to be expected, since this is a fissure eruption and it has mostly been erupting from the same vents during the past four weeks.

It has become a bit difficult to get accurate information on what is going on El Hierro Island. So I am not going to speculate on that. But from what I can gather it seems that dangerous gas level has been detected on the ground. But the reports that I am reading are bit unclear on this. This has also been mentioned in comments on this blog.

The harmonic tremor from the eruption in El Hierro volcano at 15:23 UTC on 9 November, 2011. Copyright of this picture belongs to IGN.

As can be seen on this tremor plot the harmonic tremor in the eruption is dropping. Explosions that have taken place are also clear on this tremor plot. That might be because the eruption vent is getting smaller, therefor less magma is being push out the erupting vent. Or the currently erupting vent might be closing up. As so often happens with fissure type eruptions. If that happens does not mean that this eruption cycle is over. It just means that the current eruption vent has closed up. New fissures are most likely to open up in coming weeks as the eruption goes on. Where and when it impossible to know for sure.

Earthquake activity continues in north part of El Hierro volcano. This are most likely dike intrusions into the bed rock there. So earthquake activity should be expected to continue north west of the town Frontera. If a dike intrusion manages to find a path to the surface in this area there is going to be a eruption and earthquake activity should drop following that. But until and if that happens there are going to be earthquakes. There is also chance of hydrothermal activity to show up in this area if a dike intrusion gets shallow into the bed rock. But is not go up from the ground and start a eruption. This might also be the reason why some part of El Hierro Island are experiencing high levels of toxic gas for the moment.

I am going to post more on the eruption in El Hierro volcano as I know more what is going on.