Increasing seismicty at Chaiten as the one-year anniversary approaches

Chaiten erupting on January 19, 2009. Image courtesy of the NASA Earth Observatory.

It is hard to believe that we are less than one month away from one-year anniversary of the beginning of the eruption at Chaiten (and with it, the one-year anniversary of this blog!) The volcano in southern Chile is still erupting away, creating at least 2 dome complexes within the older caldera. These domes have been experiencing periodic collapses, creating block & ash flows, some of which have made it out of the caldera and down close to the ghost town of Chaiten. Along with the block & ash flows, ash columns in the 10,000s feet / 3-5,000s meters continue to be producing, raining ash on areas to the east of the volcano.

And just when you might wonder when this eruption might end, the SERNAGEOMIN announced today that seismicity has been increasing at Chaiten (in spanish) over the last few weeks, peaking over the weekend (4/11-12) with earthquakes as large as M4.5. Now, what this means is still up for interpretation, but increased seismicity might indicate that we could see an increase in the eruptive rate at the volcano caused by magma moving upwards, or this might reflect increased gas flux under the domes. In either case, something to keep watching carefully – especially after the discovery of a new rhyolite spine (in spanish) growing on the domes.