Looks like another Chilean volcano could be becoming restless. The SERNAGEOMIN and OVDAS raised the alert status at Hudson in southern Chile (spanish) after an moderate earthquake swarm occurred at the volcano overnight. The report says that over 100 earthquakes have occurred since yesterday, mostly at depths between 15-25 km depth below the volcano and all to the NW of the caldera. The swarm appears to have tapered some today, but looks to be continuing. It seems that the swarm is serious enough for Chilean officials to begin to evacuate people who live near Hudson and ONEMI has declared a red alert status for communities near the volcano. UPDATE 5:10 PM EDT: The SERNAGEOMIN is now reporting a thin ash plume from Hudson as well. UPDATE 5:45 PM EDT: And now we have an image of the thin ash/steam plume (see below) - you can see a sequence of images of the plume as well. {Special thanks to @asvarela and @aficientifico}.
Hudson is one of the more active volcanoes in southern Chile with its last eruption coming in 1991 - and it was one of the largest of the 20th century. The 1991 activity was a VEI 5 with explosive event from the main caldera that sent ash over Argentina and noticeable ash as far away as the Falkland Islands, a full 1000 km from the volcano. The volcano is ice-covered, so multiple jokulhlaups and mudflows were produced during the eruption as well. This eruption produced a sulfur dioxide plume that was tracked across much of the southern hemisphere and effected the snow and air chemistry of Antarctica. Hudson is thought to have produced some of the largest eruptions in southern South America, including multiple VEI 6 eruptions that produced over 10 km^3 of tephra. You can read all about Hudson in a paper by Gutierrez and others (PDF). UPDATE 6:30 PM EDT: Another image of the eruption (below), this time closer to the vent - you can clearly see ash falling from the plume. You can also watch a press conference from CNN Chile (video) from the Chilean government. {Special thanks to Eruptions reader Sherine for the links}.
