Event Name : Veniaminof 2005/9
|Start:||September 7, 2005 ||Observed|
|Stop:||November 4, 2005 ||Observed|
|Tephra plume: ||
|Minor explosive eruption: ||
|Duration: ||About 2 months ||
|MaxVEI: ||1 ||
|ColHeight: ||3000 m ||
From McGimsey and others (2007): "Veniaminof remained relatively quiet [since February, 2005] until early September when several minor bursts of ash were observed by Perryville residents and visible on the web camera (see fig. 34 in original text). This and an increase in seismicity prompted AVO to elevate the Level of Concern from Green to Yellow on September 7. The minor unrest continued only for a couple of weeks when seismicity once again decreased to background level and there were no observations of emissions. AVO reduced the Level of Concern from Yellow to Green on September 28.
"Then, on November 4, a low-level, minor ash emission visible in the webcam prompted AVO to raise the Level of Concern from Green to Yellow. Slightly elevated seismicity persisted for the next few weeks but poor weather conditions precluded visual observations. By mid-December, seismic levels were again down to background level, and on December 30, the Level of Concern was downgraded from Yellow to Green, the 8th Color Code change of the year for Veniaminof (see table 6 in original text)."
From the Smithsonian Institution (2006, v. 31, n. 3): "On 7 September 2005, the Alaska Volcano Observatory (AVO) noted several minor bursts of ash from the volcano during the afternoon. Ash bursts continued to occur through at least 9 September, with ash rising less than 3 km altitude, and with the ash confined to the caldera. Over the following 2 weeks, minor ash emission continued at a rate of 1-5 events per day based on interpretations of seismic data. AVO reported that it was likely that diffuse ash plumes rose to heights less than ~ 3 km and were confined to the summit caldera. Cloudy weather during 16-23 September prohibited web-camera and satellite observations of Veniaminof, but seismic data indicated diminishing activity. On 28 September seismicity had remained at background levels for over a week, and there was no evidence to suggest that minor ash explosions were continuing.
"On 4 November 2005, a low-level minor ash emission occurred from the intracaldera cone beginning at 0929. Ash rose a few hundred meters above the cone, drifted E, and dissipated rapidly. Minor ashfall was probably confined to the summit caldera. During the previous 2 weeks, occasional steaming from the intracaldera cone was observed. Very weak seismic tremor and a few small discrete seismic events were recorded at the station closest to the active cone. However, AVO reported that there were no indications from seismic data that a significantly larger eruption was imminent."
Execerpts from AVO's weekly updates and information releases for this time period can be found at this website: http://www.avo.alaska.edu/archives/Veniaminof_2005_09.php