VENIAMINOF Alaska Peninsula, USA 56.17°N, 159.38°W; summit elev. 2,507 m; All times are local (= UTC - 9 hours [or 8 hours early April-late October]) Reports from 2002: | September | October | November | Reports from 2003: | January | February | March | April | Reports from 2004: | February | March | April | May | June | July | August | September | October | Veniaminof Eruptive History Information from the USGS Global Volcanism Program -------------------------------------------------------------------------------- 11-17 September 2002 On 10 September AVO detected 1-minute-long pulses of low-frequency tremor occurring every 2-5 minutes on several seismic stations at Veniaminof. This type of seismicity is indicative of volcanic unrest. Retrospective analysis of seismic data suggested that tremor began as early as 8 September. Through at least 16 September the overall level of seismicity decreased, but remained above background levels. Veniaminof was at Concern Color Code Yellow. Source: US Geological Survey Alaska Volcano Observatory -------------------------------------------------------------------------------- 18-24 September 2002 Pulses of low-frequency tremor were first recorded on 10 September by several seismic stations at Veniaminof. Until at least 20 September the overall level of seismicity decreased, but remained above background. AVO did not receive any reports of anomalous activity, and poor weather limited satellite observations. Due to the anomalous seismicity, the Concern Color Code remained at Yellow. Source: US Geological Survey Alaska Volcano Observatory -------------------------------------------------------------------------------- 25 September-1 October 2002 AVO reported that seismic unrest that began at Veniaminof on 10 September continued through the 27th. The intensity of tremor and small earthquakes under the volcano had decreased since the 10th, but remained above the background level established during the summer of 2002. Visual observations of Veniaminof were hampered by poor weather. On 24 September, residents of Perryville, 35 km S of the volcano, reported and photographed small bursts of steam, possibly containing minor amounts of ash, rising just above the historically active intracaldera cinder cone. Without additional observations, AVO could not determine if this indicated very low-level eruptive activity or vigorous steaming from the cone. On several occasions of relatively clear weather conditions, AVO observed no signs of elevated temperature or ash emission on satellite imagery. Due to the continuing seismicity and reports of unusual steaming, the Concern Color Code remained at Yellow. Source: US Geological Survey Alaska Volcano Observatory -------------------------------------------------------------------------------- 2-8 October 2002 Veniaminof remained restless during 26 September to 4 October. Seismicity was lower than when it was first noted in early September, although it was still above background level. Visual observations of Veniaminof were intermittent and inconclusive. AVO received reports ranging from minor-steam and possible ash emissions, to no signs of activity. A satellite image recorded on 2 October suggested an apparent gray, diffuse deposit extending across the caldera from the historically active intracaldera cinder cone. This could reflect a small explosion, vigorous steam emission, or redistribution of material on the cone by strong winds. No thermal anomalies were observed on satellite imagery. AVO considered the activity at Veniaminof to be minor, but the exact nature of the unrest remained unknown. Due to the continuing seismicity and reports of unusual steaming, the Concern Color Code remained at Yellow. Source: US Geological Survey Alaska Volcano Observatory -------------------------------------------------------------------------------- 9-15 October 2002 Veniaminof remained restless during 4-11 October. Although seismicity was lower than when first noted in early September, it was still above background levels. Visual observations of Veniaminof during the week were intermittent and inconclusive. No thermal anomalies were observed on satellite imagery. AVO considered the activity at Veniaminof to be minor, but the exact nature of the unrest remained unknown. The Level of Concern Color Code remained Yellow due to the continuing seismicity. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 16-22 October 2002 Veniaminof remained restless during 11-18 October. Although seismicity was lower than when first noted in early September, it was still above background levels. No new visual observations had been received since the last update. However, local observations of low-level activity earlier in the month confirm that small explosions at the intracaldera cone are possible at any time and may not correspond with a noticeably elevated level of seismicity. No thermal anomalies were observed on satellite imagery. AVO considered the activity at Veniaminof to be minor, but the exact nature of the unrest was unknown. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 23-29 October 2002 Veniaminof remained restless during 18-25 October. Although the current seismic activity is lower than when first noted in early September, it is still above background level. No new visual observations of Veniaminof were received since the last update. No thermal anomalies were observed in satellite views. AVO considered the activity at Veniaminof to be minor, but the exact nature of the unrest was unknown. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 30 October-5 November 2002 Veniaminof remained restless during 25 October to 1 November. Although the current seismic activity is lower than when first noted in early September, it is still above background level. AVO received video footage recorded in early October that showed minor ash emission from the intracaldera cone. The ash rose about 100-200 m above the cone and drifted a short distance before dispersing. A faint covering of ash was visible on the caldera ice field extending from the base of the cone. These observations are consistent with the elevated level of seismicity and are indicative of the type of minor activity that is occurring. Due to the continuing seismicity and reports of minor ash emissions the Concern Color Code at Veniaminof remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 13-19 November 2002 On 18 November AVO lowered the Concern Color Code at Veniaminof from Yellow to Green. Since early October they had received no pilot reports or other observations of activity at the volcano. Also, they had not detected thermal anomalies in any clear satellite images. Though seismicity remained above levels recorded this summer, it has remained roughly constant for the past month at a level notably lower than in September, when the color code was raised to Yellow. AVO stated that while Veniaminof is in its current state of activity, low-level steaming and minor ash emissions may periodically occur. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 31 December 2002- 7 January 2003 Periods of nearly constant seismicity at Veniaminof since 31 December led AVO to raise the Concern Color Code from Green to Yellow on 6 January. Seismicity had been increasing since mid-December. No thermal anomalies were detected on satellite imagery. AVO stated that there were no indications of an imminent eruption, although low-level steaming and minor ash emission may occur. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 8-14 January 2003 The elevated seismicity that began in mid-December 2002 at Veniaminof continued during 3-10 January. Nearly constant periods of seismicity were recorded during the report week. Discrete seismic events occurred at rates up to 1-2 events per minute, along with moderate levels of volcanic tremor. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 15-21 January 2003 The elevated seismicity that began in mid-December 2002 at Veniaminof continued during 10-17 January. As during the previous week, periods of nearly constant seismicity were recorded during the report week. Discrete seismic events occurred at rates up to 1-2 events per minute, along with moderate levels of volcanic tremor. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 22-28 January 2003 The elevated seismicity that began in mid-December 2002 at Veniaminof continued during 17-24 January. As during the previous week, periods of nearly constant seismicity were recorded during the report week. Discrete seismic events occurred at rates up to 1-2 events per minute, along with moderate levels of volcanic tremor. Satellite imagery did not reveal increased surface temperatures, ash emission, or ash deposits. Visual observations on 22 January from the village of Perryville, located 35 km SSW of the volcano, revealed that white steam was rising from the intracaldera cone. The steaming was similar to that observed over the previous several months. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 29 January- 4 February 2003 The elevated seismicity that began at Veniaminof in mid-December 2002 continued through 24-31 January. Discrete seismic events occurred at rates up to 1-2 events per minute, although event rates and peak amplitudes decreased somewhat over the last 2 days. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 5-11 February 2003 The elevated seismicity that began at Veniaminof in mid-December 2002 continued through 31 January to 7 February. Discrete seismic events occurred at rates up to 1 event per minute. AVO stated that at this level of seismic unrest, low-level steaming and minor ash emissions may occur at any time. No elevated surface temperatures, ash emissions, or ash deposits were noted on satellite images. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 12-18 February 2003 The elevated seismicity that began at Veniaminof in mid-December 2002 continued through 7-14 February. Discrete seismic events occurred at rates up to 1 event per minute. AVO stated that at this level of seismic unrest, low-level steaming, and minor ash emissions may occur at any time. No elevated surface temperatures, ash emissions, or ash deposits were noted on satellite images. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 12-18 March 2003 The elevated seismicity that began in mid-December 2002 at Veniaminof continued during 7-14 March. On 11 March a 4-hour period of continuous seismic tremor was recorded, followed by 17 hours of discrete seismic events and 3- to 4-minute-long tremor bursts. This culminated with another 4-hour period of continuous tremor on 12 March. Seismicity then declined, and by the 14th was characterized by the occurrence of about one small-amplitude discrete seismic event every 1-2 minutes. AVO reported that based on this seismicity, low-level steaming and minor ash-emissions may occur at any time. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 26 March-1 April 2003 The elevated seismicity that began in mid-December 2002 at Veniaminof continued during 21-28 March, but declined in comparison to previous weeks. Seismicity was characterized by very low amplitude tremor. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 2-8 April 2003 Seismicity dramatically decreased at Veniaminof during 28 March to 4 April. However, short periods of volcanic tremor and low-frequency events continued to occur. AVO reported that low-level steaming and minor ash emissions might occur at any time. The Concern Color Code remained at Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 9-15 April 2003 Seismic activity remained at very low levels at Veniaminof during 4-11 April. Tremor was almost completely absent, and only a few low-frequency events were recorded. Satellite images during the week did not reveal any elevated surface temperatures, ash emissions, or ash deposits at the volcano. Due to the decline in seismicity, AVO lowered the Concern Color Code for Veniaminof from Yellow to Green. AVO stated that while Veniaminof is in its current state of activity, low-level steaming and minor ash emissions may periodically occur. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 18-24 February 2004 During the week of 15 February, AVO received several reports of small ash clouds rising "several hundred feet" above the intracaldera cinder-and-spatter cone of Veniaminof. Residents of Perryville reported a "black puff" of ash on 16 February followed by strong steaming, and a pilot reported a small black ash cloud on 19 February. Satellite imagery on 19 February at 1410 showed a small, dark trail on the snow leading away from the intracaldera cone that was likely a very localized ash deposit. No significant seismic activity or thermal anomalies on satellite data were recorded during the week. Due to the lack of significant seismic activity beneath the volcano, AVO concluded that these small ash clouds were the result of minor explosions caused by the heating of ground water below the intracaldera cone. Veniaminof remained at Concern Color Code Green. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 25 February- 2 March 2004 Following reports of low-level steam-and-ash emissions from Veniaminof during the week of 15 February, satellite imagery on 22 February showed very localized ash deposits within the ice-filled caldera. No additional signs of volcanic activity were visible on satellite imagery during 23-27 February, and there were no more reports of ash-plume sightings from Perryville. Seismicity remained at low levels, and the thermal signature of the intracaldera cone was unchanged from previous months. AVO determined that the small ash bursts were most likely the result of minor explosions caused by the heating of ground water below the intracaldera cone. Veniaminof remained at Concern Color Code Green. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 14-20 April 2004 During 10-17 April, Veniaminof showed heightened seismicity with several episodes of volcanic tremor and earthquakes. Seismicity decreased significantly prior to the emission of a gas plume with some ash throughout 18 April. The most vigorous phase occurred at about 1730 on 18 April when the plume rose to ~0.5 km above the crater. At about 1130 on 19 April another period of heightened seismic activity began. Due to the increased activity, Veniaminof was upgraded to Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 21-27 April 2004 After a period of heightened seismicity at Veniaminof during 14-17 April that led AVO to increase the Concern Color Code from Green to Yellow, there was a marked decrease in the episodes of low-level volcanic tremor and small volcanic earthquakes through 26 April. A newly installed internet-based video camera located in Perryville allowed AVO to observe the volcano during clear weather. During the afternoon and evening of 25 April, more than 25 small steam-and-ash emissions were seen during an 8-hour period, producing clouds that rose 300-600 m above the active cone. These clouds typically were confined to the summit caldera, but could pose a hazard to people and low-flying aircraft in the immediate vicinity of the active cone. Through 26 April, Veniaminof remained at Concern Color Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 28 April- 4 May 2004 Unrest at Veniaminof during 23-30 April was characterized by small intermittent ash emissions, low-level volcanic tremor, and small volcanic earthquakes. Small ash emissions were observed during clear weather on 25 and 28 April rising to ~1 km above the active cone. Seismic activity fluctuated, but remained above background levels. There were no indications that more vigorous activity was imminent. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 5-11 May 2004 Unrest continued at Veniaminof during 30 April to 7 May, characterized by small intermittent ash emissions, low-level volcanic tremor, and small volcanic earthquakes. Small ash emissions were observed during periods of clear weather during 1-3 May, rising to 2.4-2.8 km a.s.l. Seismicity was at levels similar to the previous week, suggesting that ash-burst activity continued. Satellite imagery showed ash deposits on the volcano's snow-covered flanks as far as ~8 km from the vent. A pilot reported seeing ash as far as 33 km from the cone. Veniaminof remained at Concern Color Code Yellow. Sources: Alaska Volcano Observatory, Anchorage VAAC -------------------------------------------------------------------------------- 12-18 May 2004 During 7-14 May unrest continued at Veniaminof, characterized by intermittent low-level volcanic tremor and small volcanic earthquakes. No emissions were seen. In comparison to the previous week, seismicity was more intermittent and lower in amplitude. However, seismicity suggested that ash bursts occasionally occurred. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 19-25 May 2004 Unrest continued at Veniaminof during 14-21 May, characterized by intermittent volcanic tremor. The tremor was similar to seismic signals recorded the previous month in association with small ash plumes, suggesting that ash bursts continued. A pilot report on 18 May indicated the presence of an ash plume rising to heights of 300-900 m above the volcano's summit and extending ~32 km NE. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 26 May- 1 June 2004 During 21-28 May, the level of volcanic activity at Veniaminof was generally lower than during the previous week. Sequences of tremor accompanying ash bursts continued. On video, weak steaming and low ash bursts were seen emanating from the intracaldera cone. Most of the ash bursts did not rise above the active cone (2,156 m). Satellite imagery on 26 May showed ash deposits on the N and SE portions of the caldera. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 9-15 June 2004 Bursts of volcanic tremor continued at Veniaminof during 4-11 June. The only significant ash emissions occurred during the evening of 30-31 May. No emission exceeded 3 km a.s.l. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 16-22 June 2004 During 11-18 June, bursts of volcanic tremor continued intermittently at Veniaminof that may have been indicative of small, low-level ash emissions. On 16 June at 2350, a pilot observed an ash cloud that rose to a height of ~2.7 km a.s.l. The plume was also visible on satellite imagery. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 30 June- 6 July 2004 Short intervals of volcanic tremor occurred at Veniaminof during 25 June to 2 July. AVO reported that the tremor could be indicative of small, low-level ash-and-steam emissions. Small amounts of dark ash were seen in the ice-filled caldera on 27 June. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 7-13 July 2004 Many episodes of short-lived bursts of volcanic tremor continued at Veniaminof during 7-13 July. AVO reported that the tremor correlated well with ash-and-steam plumes as high as 1.5 km a.s.l. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 14-20 July 2004 Short intervals of low-level volcanic tremor continued intermittently at Veniaminof during 9-16 July. According to AVO, the episodes of tremor correlated well with small ash-and-steam emissions that may have reached as high as 3.6 km a.s.l. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 21-27 July 2004 Small steam-and-ash emissions were accompanied by periods of volcanic tremor at Veniaminof during 16-23 July. On 22 July at 1229, an AVO field crew witnessed a small ash burst rise a few hundred meters above the summit of the intracaldera cone. This type of activity prevailed at Veniaminof during the previous 3 months. During periods of repose in the report week, the cone produced variable amounts of white steam from at least two separate craters near its top. The snow-and-ice field over much of the caldera was covered with a discontinuous, 1- to 2-mm thick ash blanket. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 28 July- 3 August 2004 Episodes of volcanic tremor continued intermittently at Veniaminof during 22-30 July. No visual observations of ash emissions were made after 22 July, although the recorded seismicity was similar to that observed during ash emissions in the previous few months. Most such emissions did not reach 3 km a.s.l., though a few reportedly reached as high as 3.7 km. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 4-10 August 2004 Episodes of volcanic tremor continued intermittently at Veniaminof from 30 July to 6 August. No visual observations of ash emissions had been made since 22 July, although the recorded seismicity was similar to that observed during ash emissions in the previous weeks. During the report period, occasional low-level steam plumes were seen on the AVO web camera. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 11-17 August 2004 During 6-13 August, frequent small ash-and-steam emissions from Veniaminof were visible on the web camera in Perryville and confirmed by AVO geologists working in the area. The emissions did not exceed a height of 3 km a.s.l. and were similar to those commonly observed in the past 2 months. Bursts of volcanic tremor recorded intermittently on 17 August were probably associated with low-level, short-term ash emissions. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 18-24 August 2004 Episodes of volcanic tremor continued intermittently at Veniaminof during 13-20 August. Occasional small ash-and-steam emissions occurred during the report week that were similar to those observed over the previous 2 months. None rose above 3 km a.s.l. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 25-31 August 2004 During 20-27 August, low-level seismic tremor and intermittent tremor bursts continued at Veniaminof. Inclement weather prohibited direct observations and satellite views. AVO scientists believed tremor episodes likely represented low-level ash-and-steam emissions similar to those observed during the previous 2 months. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 1-7 September 2004 Both low-level tremor and intermittent bursts of tremor continued at Veniaminof during 27 August to 3 September. AVO scientists believed tremor episodes likely represented low-level ash-and-steam emissions similar to those observed during the previous 2 months. Minor emissions of ash and steam were occasionally seen on the web camera during clear weather. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 8-14 September 2004 Both low-level tremor and intermittent bursts of tremor continued at Veniaminof during 3-10 September. AVO scientists believed these tremor episodes likely represented low-level ash-and-steam emissions similar to those observed during the previous 4 months. Minor emissions of ash and steam were occasionally seen on the web camera during clear weather. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 15-21 September 2004 Low-level seismic tremor and intermittent tremor bursts continue to be recorded at Veniaminof. Tremor episodes likely represent low-level ash and steam emissions similar to those observed over the past four months. Minor emissions of volcanic ash and steam were occasionally observed using web camera images during times of clear weather. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 22-28 September 2004 Low-level tremor and intermittent tremor bursts continued at Veniaminof during 17-24 September. Tremor episodes likely represented low-level ash-and-steam emissions similar to those observed over the previous 4 months, although cloudy conditions obscured views of the volcano in web camera and satellite imagery. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 29 September- 5 October 2004 During 24 September to 1 October, low-level tremor and intermittent small tremor bursts may have occurred at Veniominof, but high winds in the area made analysis of seismic records inconclusive. The winds were strong enough to produce an overshadowing effect on seismic records that could hide evidence of low-level tremor. If the tremor episodes continued, they likely represented low-level ash-and-steam emissions similar to those observed over the previous 4 months. Cloudy conditions obscured views of the volcano in web camera and satellite data. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 13-19 October 2004 Low-level tremor continued at Veniaminof during 8-15 October, correlating with weak steaming of the intracaldera cone as observed on the web camera. No ash emissions were observed, although cloudy conditions over the caldera restricted viewing for much of the week. Veniaminof remained at Concern Color Code Yellow. Source: Alaska Volcano Observatory -------------------------------------------------------------------------------- 20-26 October 2004 AVO lowered the Concern Color Codeat Veniaminof on 26 October from Yellow to Green. Seismicity, which had been associated with ash emissions that occurred during the summer of 2004, decreased to levels that indicated ash, ash-and-steam, or steam emissions were no longer occurring on a regular basis. Since early September, no ash emissions were seen on the web camera and no evidence of ash was visible on satellite imagery. Also, AVO had received no recent reports of ash from pilots or ground observers. AVO considered the intermittent, low-level seismic tremor that continued to be recorded at the volcano to be part of the background activity. They reported that steaming from the intracaldera cone may still occur. Source: Alaska Volcano Observatory