Firegeezer notes: As the seismic activity slows down in the volcano, Alaska Dave’s reports will become more sporadic. He filed this latest report last night:
2009-03-25 13:35:06 – Status Report on Mt. Redoubt:
Seismic activity at Redoubt volcano has declined over the last 36 hours, although there have been several brief increases in seismicity associated with minor low-level ash emissions. The last known ash emission was at 5:12 AKDT this morning. The plume from this event did not extend above about 15,000 feet. Based on the level of seismic activity, AVO is lowering the aviation color code to ORANGE and the volcanic alert level to WATCH.
Current seismicity at Redoubt is at times suggestive of intermittent lava extrusion at the volcano’s summit. However, the existence of a new lava dome has not been confirmed because of poor weather. Growth of lava domes is common at volcanoes like Redoubt and was observed several times throughout the last eruption of 1989-1990. As dome size increases, so does the possibility of dome collapse along with a return to a more explosive eruptive style. Though a distinct rise in seismicity often precedes dome failure, domes can fail with little or no warning and may result in a sudden explosion and ash emission.
Based on observations from the Redoubt eruption of 1989-1990, episodes of dome growth followed by explosive dome destruction is a likely but by no means certain, near-term scenario. Cycles of dome growth and failure could occur for several months. In the event of an escalation in seismic activity or confirmation of a significant ash producing eruption, AVO would accordingly raise the color code and alert level to Red/Warning.
It is possible that dome collapse events will initiate pyroclastic flows over Drift glacier that will result in meltwater generation and downstream mudflows and floods. Some of these floods could reach Cook Inlet within hours.
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