The most recent image on the AVO website of the dome at Redoubt, taken in November 2009. Image courtesy of AVO/USGS, by Cyrus Read.
Not much information on this, but AVO just raised the alert status at Redoubt in Alaska to Yellow for the first time since late September. A series of small earthquakes were detected near the summit dome starting at 10 A.M. today, prompting the change of status.
The link to the complete text of the change in status doesn't seem to work on the AVO site, so here it is:
2009-12-28 09:53:11 - VAN/VONA AVO is raising the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY at Redoubt volcano. At roughly 16:00 AKDT yesterday Dec. 27 (0100 Dec. 28 UTC) a series of small repetitive earthquakes began occurring in the vicinity of the volcano's summit. Activity is continuing this morning. See http://www.avo.alaska.edu/webicorders/Redoubt/RSO_EHZ_AV.phpThese earthquakes may be precursory to renewed eruptive activity at the volcano and increased instability of the lava dome. Whether this will result in explosive activity or failure of the lava dome is unknown at this time. However, there is a heightened possibility of volcanic activity that would produce a volcanic ash cloud, pyroclastic avalanches, and lahars and flooding down the Drift River.
Stay tuned ... Redoubt might be trying to make a comeback for 2009 Pliny!
Physical Science
Environment
Comments (179)
I'm not an expert, but from what I understand the small earthquakes occurring at regular intervals right now (visible from the RSO webicorder) are the symptom of increased outgassing in progress (probably a breach in the settled and hardened layers of the current lava dome has been made).
Since when the volcano status change has been issued by AVO, the amount of these small earthquakes has decreased, but the amplitude of them has increased by roughly about 15-20%.
I haven't seen long period tremors or otherwise low frequency signals usually associated with the movement of magma.
Anyway, I stress that I'm not an expert, this is just my uneducated analysis.
Posted by: SHIRAKAWA Akira | December 29, 2009 10:03 AM