On the Llaima volcano eruption (pt. 1)

24 hours have not passed yet since Llaima volcano, placed in the sourthern Andes of Chile, entered in a new eruption cicle. The last eruption of this stratovolcano was in 1994, with a moderate ejection of tephra and lava.

This eruption came preceded of an amount of the volcanic activity towards the last half of 2007. Also, in the last weeks, little earthquakes were registered in the northern and central zone of Chile. The natural question that can be done is: "is there a relationship between these little earhquakes and the activity of the Llaima volcano?" When the subduction between the Nazca and Southamerican tectonic plates is considered as the main cause of earthquakes and volcanic eruptions in Chile, the answer to that question is yes. However, it is not a direct relationship, because the processes involved in a volcanic eruption are not simple and a thing like "there is always a volcanic eruption when there is a earthquake" can not be said. Actually, more than a 50% of the volcanic eruptions happens a little before or later (from minutes to 1 or 2 months) a big earthquake, like the one in Tocopilla.

With this relationship established, the next step is to see how dangerous is this eruption of the Llaima volcano. Considering that the main danger of this volcano are the lahars, then the first zone of danger is the one enclosed by the blue line in the next figure, due to a possible increase in the level of the rivers ans lakes near to the center of the eruption. Also, an approximate area covered by the tephra plume is painted in grey, and the typical lava courses are sketched with yellow. Obviously all this areas are estimations, and can vary depending of how strong the eruption can be.



At the moment this eruption has not been a really big one. The lahars have been small and there has not be a long snow melting. There have been no people harmed or dead and there is not a tephra plume and lava emission from the main crater of the volcano as there was yesterday's evening and last night, where the tephra plume reached more than 3000 meters high and the lava emission generated a beautiful show as can bee seen here (thanks jecka!) and here (emol.cl).

I will be writting a little more about this topic soon. Keep an eye on the Llaima volcano!