Today we have seen a change in the behaviour at Pevolca, now they have changed the level of alarm from green all over the island, to yellow for Julan and La Dehesa. They are also asking everyone on the island to familiarise themselves with the plans for evacuation and self protection.
The center for the current magmatic earthquake swarm has moved slowly since yesterday to the west and south. And the magmatic component of the waveforms have increased in clarity. As you can see in the image above (provided directly by courtesy from IGN to Volcano Café) the center of attention yesterday was at Julan. There has also been rapid inflation during the last two days with clear movement patterns associated with magmatic movement, and new magma arrival. The numbers are high for such a short time period, between 2 and 3 centimeters. Commentator Vishy pointed me to a paper by Stroncik regarding chrystalization in magmatic chambers, and in this case the depth necessary is somewhere between 16 and 23 kilometers down. This means that the earthquakes we have seen in this depth region is where the magma chambers are.
As you can see in the image this increases the risk for an eruption occuring in the southern fissure zone ranging from La Restinga up towards Tanganasoga. If a new feeder channel is opening up we will first see migratory earthquakes in the region between 16 and 8 kilometres, after that we will most likely see an onset of eruption within a few hours. It is therefore very important to study carefully the plots to see where the conduit is forming. The likelihood of a new eruption starting is now very high. I would like to tell any readers of this blog who lives on El Hierro to check often for new data, especially the IGN Earthquake positioning map. If you live in the area ontop of where the earthquakes are forming in the 16 – 8 kilometer depth level, you would do well by moving yourself away to safer grounds, best and safest part is to the northeast on the island (very low risk for eruption there). You are of course welcome to check in here also for new information in the comments, if anything happens it is most likely to find the information you need there. http://www.01.ign.es/ign/resources/volcanologia/jpg/Eventos_HIERRO_2D.jpg