We’ve been hearing a lot of conflicting reports about the state and future of the Chaiten eruption. Now ending its fourth week of eruption, Chaiten was said to be easing up a bit, but recent reports have Luis Lara from the SERNAGEOMIN still worried about a potential collapse, followed by a devastating eruption. I’ll have to take his word for it as the explanations in the article don’t really make a lot of sense. It sounds like both Lara and Dr. Petrinovic (Argentina) are worried about dome collapse, but that would just form large pyroclastic flows … unless the dome collapses enough to release the pressure on the underlying magma, then maybe you could get a large eruption (see Mt. Saint Helens, 1980). I also have some compositional data from ash erupted at Chaiten (big thank you to reader Werner Luis for finding these). Most of the ash is rhyolite (73-75 wt% SiO2), but at least a couple are dacite (64-65 wt% SiO2), which indicates that the composition of the lava/ash erupting has changed during the eruption. There isn’t much context to the data, but it is still interesting nevertheless.