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1100: A strong seismic signal on the Redoubt and more distant stations was noticed by J. Paskievitch around 1100 on Thursday 8/13. (See description of seismicity by A. Jolly and S. Stihler).
Subsequent discussions with J. Power indicated strong suspicion of a land-slide origin; not 100% certain.
Called Drift River Oil Terminal (DROT) - partly clear weather, hadn't heard or seen anything unusual.
Called NWS - could see a "dark spot" (thermal anomaly?) on image over approximate position of Redoubt.
Later in the afternoon, J. Dorova joined a DROT fixed wing from Kenai and overflew Redoubt; said he saw no change in Drift River but clouds obscured most of dome and north canyon; no evidence of any major disruption. 300 m steam plume over crater.
1930: J. Eichelberger called T. Neal at home, a strong 12-minute signal at RSO. He also called C. Rowe.
T. Neal goes to AVO-Anchorage; called DROT, no sign of anything, mountain is clear although an "odd" looking cumulus cloud sits at the north base of the mountain. Has a conference call with J. Eichelberger, B. Page, J. Power. Facts: big event; in early days we would have called this an eruption; need aerial observations to verify what this is; attempted location and got a very large error; emergent signal problem. Similar to ash and gas emissions from Mount St. Helens but much more energetic, they are not similar to phreatomagmatic signals of Fall 1990 from Redoubt. Didn't set off any alarm because too emergent. No LP signature in SSAM (which did occur in Fall 1990 seismicity). FAA received no PIREPS today of any plume/unusual activity.
2200: Decided to put out an update noting strong seismicity of probably landslide origin but to continue checking seismicity through the night. Checked LDS, no strikes.