According to today's Anchorage Daily News article, Alaskan volcanos don't have the pretty, fluid lava that Hawaiian volcanos do. Instead, our volcanos have a more sticky magma that will ooze out a little before hardening. Pressure keeps building beneath this newly hard surface until *BLAM* the whole top gets blown off!
Apparently this is called "pyroclastic." I first heard this word a few years ago when I was out in the Pribilofs. I was checking out some very cool, very shiny rocks that were scattered across the island. A geologist on the project told me these were pyroclastic rocks, meaning that when the volcano (the island) had last blown, bits of magma shot through the air hardened to form these rocks.
We also played in some lava tubes on that trip, I'll have to find a picture to post. Things like this make me want to be a geologist. Ok, really right now I want to be a vulcanologist.
Here are some pics from the Alaska Volcano Observatory (photo credits: Cyrus Read, AVO/USGS). Check out their site for more pics and status updates: http://www.avo.alaska.edu/activity/Redoubt.php
Summit crater showing rapidly melting glacier and enlarged "ice piston" feature.
Flood waters generated in the summit crater of Redoubt descending down through an ice gorge on Drift Glacier.
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