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Bogoslof reported activity

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EVENT SPECIFIC INFORMATION

Event Name : Bogoslof 2016/12

Start:December 12, 2016 Observed

Tephrafall: BibCard BibCard BibCard
Lava dome: BibCard
Tephra plume: BibCard
Phreato-magmatic: BibCard
Island-forming: BibCard
Submarine: BibCard
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Eruption Type:Explosive
ColHeight: 10300 m BibCard
MaxVEI: 3 BibCard
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Description: Bogoslof's 2016-2017 active eruption sequence began at least by December 16, although retrospective analysis done by AVO suggests unrest may have started earlier in December. Explosions detected in retrospective analysis occurred on December 12, 14, 16 and 19.

On December 20, 2016, at about 3:35 PM AKST (00:35 UTC, December 21), Bogoslof volcano began an explosive eruption that lasted about 30 minutes and produced a detached ash cloud that rose to 34,000 ft (10.3 km) above sea level, as reported by several pilots. At 5:20 pm AKST, AVO raised the Aviation Color Code and Volcano Alert Level for Bogoslof from UNASSIGNED to RED/WARNING. A subsequent pilot report from 4:30 pm AKST (01:50 UTC December 21) indicated that activity had decreased and the cloud was dispersing. The ash cloud was carried southward over the Gulf of Alaska and no ash fell on inhabited areas. As of 8:54 am December 21, 2016, no further explosions had been detected in seismic and infrasound networks indicating that the activity has subsided. No activity was apparent in recent nighttime satellite images.

Further explosions occurred on December 21, 23, 26, 28, and 30. The events of December 21 and 26 produced water-rich and relatively ash-poor volcanic clouds that rose as high as 10.7 km (35,000 ft) above sea level and were tracked in satellite images as they were transported with the prevailing winds. Sulfur dioxide gas clouds from many of these events have been detected in satellite data, and the largest event on December 21 was tracked in satellite data for five days to a location over the central United States (Nebraska).

Explosions and ash emissions at Bogoslof have continued into 2017, with eruptions on January 2, 3, 5, 8, 12, 15, 17, 18, 20, 22, 24, 26, 27, 30-31, February 3 (UTC, February 4), 13, 17, 18, 19 (UTC, February 20), March 7 (UTC, March 8), March 13, and May 16 (May 17 UTC). The events of January 5 and 8 produced volcanic clouds that rose as high as 10.7 km (35,000 ft) above sea level. Pilots reported that the January 18 (13:20 AKST; 22:20 UTC) ash cloud reached a height greater than 9.5 km (31,000 ft) above sea level. Satellite observations showed the January 18 ash cloud to be darker in color, and presumably more ash-rich, than others in this eruptive sequence, suggesting the presence of very hot material (lava) at the surface immediately surrounding the vent - the first such observation during this eruption sequence. An article feature online on the Earth, the Science Behind the Headlines website reported that "On January 11, 2017, a flight from Tokyo to Minneapolis was rerouted southward due to low-level ash emissions from Bogoslof Volcano in the Aleutian Islands. Although no significant eruption occurred, the plane continued along the modified flight path rather than risk rerouting midflight in the event of increased volcanic activity" (https://www.earthmagazine.org/article/airplanes-and-ash-clouds-what-weve-learned-eyjafjallaj%C3%B6kull). The Alaska Dispatch News reported that the January 18 ash cloud affected at least three or four flights at a minimum (https://www.adn.com/alaska-news/aviation/2017/01/19/another-bogoslof-eruption-sends-ash-over-alaska-peninsula-kodiak-island/). As a result of the January 30-31, 2017 eruption, which produced a volcanic cloud with an estimated altitude of 7.6 km (25,000 ft) above sea level, small amounts of ashfall and a sulfurous smell were reported on Unalaska, 61 miles (98 km) away (https://www.adn.com/alaska-news/environment/2017/01/31/unalaska-receives-ashfall-after-bogoslof-eruption/). Jennifer Shockley, Unalaska Department of Public Safety deputy director, reported that "About a dozen flights to or from Unalaska over the past 10 days [prior to January 31] had been canceled due to previous ashfall in the region…" (https://www.adn.com/alaska-news/environment/2017/01/31/unalaska-receives-ashfall-after-bogoslof-eruption/). Residents of Dutch Harbor reported trace ashfall to the Alaska Volcano Observatory following the March 7 (UTC, March 8) Bogoslof eruption.

AVO lowered the Bogoslof Aviation Color Code and Volcano Alert Level from Orange/WATCH to Yellow/ADVISORY on April 5, 2017. On April 15, 2017, an increase in earthquake activity from Bogoslof was detected from stations on nearby islands starting around 15:01 AKST / 23:01 UTC. Although there was no evidence of renewed eruptive activity from infrasound, lightning, or satellite data, AVO raised the Aviation Color Code for Bogoslof to ORANGE and the Volcano Alert Level to WATCH because the uptick in seismicity increases the likelihood of future explosive activity. Following an absence of dectected activity over the next several days, AVO lowered Bogoslof's Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY on April 19, 2017, following an absence of of new volcanic activity in satellite, seismic or infrasound data since the small explosion was detected on March 13.

Around 10:32 pm, May 16, 2017 AKST (06:32 UTC May 17), AVO detected an increase in seismic and infrasound activity at Bogoslof. AVO raised the Aviation Color Code and Volcanic Alert Level to ORANGE/WATCH at 11 pm May 16, 2017 AKST. AT 11:26 pm AKST (07:26 May 17 UTC), AVO raised the alert levels to RED/WARNING. The explosive eruption lasted about 73 minutes, and produced an ash cloud that moved southwest along the edge of a mass of weather clouds, as seen in satellite imagery. A pilot reported the plume height as 34,000 ft. Following the explosion, AVO lowered the alert levels to ORANGE/WATCH at 11:08 am May 17 AKST (1908 UTC). Trace ashfall occurred in Nikolski.

An explosive eruption at Bogoslof began at 2:16 pm AKDT (22:16 UTC) on May 28, and AVO raised the Aviation Color Code and Volcano Alert Level to RED/WARNING at 2:49 pm AKDT. This eruption continued for about 50 minutes, and produced an ash cloud that rose to at least 40,000 ft, and travelled northwest from the volcano. After the explosion, AVO lowered the Aviation Color Code and Volcano Alert Level to ORANGE/WATCH at 9:09 pm AKDT on May 28 (05:09 UTC May 29).

After several hours of very small earthquakes, a very short explosion (less than 10 minutes) occurred at 6:42 pm AKDT May 31 (2:42 UTC June 1), and produced an ash cloud that rose to ~24,000 ft and traveled west-northwest. The Aviation Color Code and Volcanic Alert Level remained ORANGE/WATCH.

Another short duration explosive event (less than 2 minutes) occurred at 7:50 am June 5 AKDT (15:50 UTC). This explosion produced a small volcanic cloud that rose to about 20,000 ft. The Aviation Color Code and Volcanic Alert Level remained ORANGE/WATCH. Later that day, AVO detected low-level seismic tremor from Bogoslof and a US Fish and Wildlife Service vessel reported seeing a large white plume rising several thousand feet above sea level.

A short-duration explosive event (less than 2 minutes) also occurred at 6 am June 6, AKDT (14:00 UTC), followed by a slightly larger explosion (about 2 minutes, indicated by seismic signals) on June 7, AKDT (14:30 UTC). On June 7, AVO reported observing a new lava dome in satellite data from earlier that day. The dome was located in the northern portion of the vent lagoon, had breached sea level, and was about 110 m across. In addition, a robust steam plume was visible in satellite data, and at 2250 UTC (14:50 AKDT) extended for 75 km to the south over the western end of Unalaska Island at an estimated altitude of less than 10,000 ft asl. Later that day, a short duration explosive event occurred at Bogoslof volcano at 5:28 UTC on 8 June (21:28 AKDT on 7 June). The duration of the event was less than 2 minutes, and seismic and infrasound signals indicated that the event was very similar to the event from earlier that day. For the June 6-7 events, the Aviation Color Code and Volcanic Alert Level remained ORANGE/WATCH.

On June 10, explosive eruptive activity occurred from about 3:18 to 5:28 AKDT (11:18 to 13:28 UTC) and the Aviation Color Code and Volcanic Alert Level were raised to RED/WARNING. The sequence began with a series of short infrasound signals and then, starting at about 4:16 AKDT (12:16 UTC), transitioned into several minutes-long continuous seismic and infrasound tremor signals. Satellite images of the resulting cloud showed it reached as high as 34,000 ft asl and drifted to the northwest. Satellite data also indicated that at least part of the volcanic cloud was more ash-rich than most of those seen previously in the Bogoslof eruptive sequence to date, suggesting that the eruption may have destroyed the lava dome that was emplaced earlier that week. The Aviation Color Code and Volcanic Alert Level were later lowered to ORANGE/WATCH.

On June 12 AKDT, a series of five explosive eruptions started at 17:47 AKDT (01:47 UCT June 13) and ended about 20:35 AKDT June 12 (04:35 UTC June 13). These events each lasted between 10 and 30 minutes and generated volcanic clouds that rose to a maximum height of 25,000 feet above sea level and dissipated within about 30 minutes. This sequence was detected in seismic, infrasound, and satellite data and a single lightning stoke was recorded. AVO raised the Aviation Color Code and Alert Level to RED/WARNING. On June 12 AKDT, residents of Unalaska/Dutch Harbor reported smelling sulfur, and winds were consistent with a source at Bogoslof. An additional six-minute-long explosion was detected in seismic and infrasound data at 8:17 AKDT June 13 (16:17 UTC), with no detected ash cloud. AVO lowered the Avaition Color Code and Alert Level to ORANGE/WATCH following no detectable activity in seismic or infrasound data.

A significant explosive eruption at Bogoslof volcano occurred at 00:49 UTC, June 24 (16:49 AKDT, June 23) and lasted about 10 minutes. The eruption produced a volcanic cloud that reached about 36,000 ft above sea level, and moved east, passing over Akutan and the North Pacific Ocean before it was no longer apparent in satellite data. AVO received no reports of ash fall. The eruption was accompanied by strong seismcity, lightning and infrasound. AVO raised the Aviation Color Code to RED and Alert level to WARNING for Bogoslof volcano. The event at 00:49 UTC was followed by four additional eruptive bursts at 3:18-3:24 UTC, 4:13-4:21 UTC, 5:04-5:12 and 5:52-5:55 UTC. High clouds obscured observations of ash clouds from these later events, with the meteorological cloud deck top at about 28,000 to 30,000 ft asl, and none of the explosive events produced a cloud that rose above it. These explosions were also detected in infrasound data, but no lightning strokes were detected by the World Wide Lightning Location Network (WWLLN). Following the events, Bogoslof seismicity remained low and nothing noteworthy was detected in satellite, infrasound or lightning data. Therefore, AVO lowered the Aviation Color Code to ORANGE and the Alert Level to WATCH at 19:54 UTC on June 24.

An eruption began at Bogoslof volcano at 00:45 UTC on June 27 (16:45 AKDT on June 26), with seismicity remaining elevated until 00:59 UTC (16:59 AKDT). The eruption produced a volcanic cloud that moved northeast with an estimated altitude of 25,000 ft asl by satellite data, and a pilot reported a visible cloud at 22,000 ft asl. Given the lower altitude of the volcanic cloud and short duration of the explosion, the Aviation Color Code was kept at ORANGE and Volcano Alert Level at WATCH.

A significant explosive eruption began at Bogoslof volcano at 11:17 UTC on June 27 (03:17 AKDT) as indicated in seismic and lighting data. The roughly 14-minute episode produced a volcanic cloud that reached an altitude of 30,000 ft asl based on satellite data, prompting AVO to raise the Aviation Color Code to RED and Volcano Alert Level to WARNING. No infrasound was detected at networks from nearby islands, but the World Wide Lightning Location Network (WWLLN) detected lightning strokes associated with the resulting volcanic cloud. No further ash emissions and low seismicity prompted AVO to later lower the Aviation Color Code to ORANGE and the Alert Level to WATCH at 3:36 AKDT on June 27.

An eruption began at Bogoslof volcano at 01:24 UTC on June 30 (17:24 AKDT on June 29). Seismicity returned to background at 01:45 UTC (17:45 AKDT) indicating an end or pause to the explosion. No ash cloud was detected, but infrasound signals recorded from Bogoslof suggest volcanic ash emissions likely occurred. Winds were towards the north. The Aviation Color Code remained at ORANGE and the Volcano Alert Level remained at WATCH.

On the afternoon of Sunday, July 2, a 16-minute-long eruption began at 12:48 AKDT (20:48 UTC) that produced a volcanic cloud reaching an altitude of 36,000 ft above sea level (asl) that was carried to the southeast, and AVO raised the Aviation Color Code and Volcanic Alert Level to RED/WARNING. The Aviation Color Code/Volcano Alert Level was reduced to ORANGE/WATCH the following day. Then on Tuesday afternoon, July 4, Bogoslof erupted twice. The first, a 13-minute-long eruption, began at 16:51 AKDT (00:51 UTC, July 5) and sent an ash cloud to 28,000 ft asl that was carried to the southeast, prompting AVO to raise the Aviation Color Code/Volcano Alert Level to RED/WARNING. The second eruption began at 19:07 AKDT (03:07 UTC, July 5), lasted 11 minutes, and put ash up to 32,000 ft asl and carried again to the southeast. Following a decline in seismicity and no further emissions, status of the volcano was reduced to ORANGE/WATCH.

On the morning of Saturday, July 8, an eruption with a total duration of 19 minutes began at 10:15 AKDT (18:15 UTC) and produced a volcanic cloud reaching an altitude of 30,000 ft above sea level (asl) that was carried to the north, and AVO raised the Aviation Color Code and Volcano Alert Level to RED/WARNING The Aviation Color Code/Volcano Alert Level was reduced to ORANGE/WATCH the following day. Overnight Sunday July 9 and into early Monday, July 10, Bogoslof erupted several times over the course of 3 hours, prompting AVO to raise Aviation Color Code/Volcano Alert Level to RED/WARNING. The first two explosions during the 3-hour-long eruption produced a small volcanic cloud reaching an altitude of 20,000 ft asl that was carried to the southeast and dissipated rapidly. About 5 hours after the end of the eruption, AVO reduced the Aviation Color Code/Volcano Alert Level to ORANGE/WATCH. Later on Monday July 10, Bogoslof had an 8-minute-long eruption beginning at 10:00 AKDT (18:00 UTC) and a 15-minute-long eruption beginning at 17:06 AKDT (01:06 UTC July 11). Neither of these two eruptions produced a significant volcanic cloud and the Aviation Color Code/Volcano Alert Level remained at ORANGE/WATCH.

A significant explosive eruption began at Bogoslof volcano at about 18:00 UTC (10:00 AKDT) on August 7 and continued through about 13:00 AKDT (21:00 UTC) as indicated in seismic, infrasound, satellite, and lightning data. AVO raised the Aviation Color Code to RED and Alert level to WARNING for Bogoslof volcano on Monday, August 7, 2017, 10:53 AM AKDT (18:53 UTC). This eruption was longer-lived than most of the events in the eruptive sequence that started in December 2016 and satellite images showed that ash from the eruption formed a continuous cloud that was carried by strong winds south over Umnak Island and then out over the Pacific. A pilot report at 18:45 UTC indicated that the ash cloud had reached 32,000 ft asl. On Tuesday, August 8, 2017, at 10:19 AM AKDT (18:19 UTC), AVO lowered the Aviation Color Code to ORANGE and the Alert Level to WATCH with no further ash emissions and low seismicity at Bogoslof.

A new lava dome was first observed at Bogoslof on August 18, 2017, and grew to about 525 ft (160 m) in diameter between August 20 - 22. Two small explosions were detected in infrasound at 4:10 AKDT (12:10 UTC) on August 22. These explosions did not produce any volcanic clouds recognizable in satellite data.

An explosive eruption occurred at 16:29 AKDT August 26, 2017 (00:29 UTC August 27), and lasted about four minutes. This explosion produced an eruptive cloud that drifted southeast from Bogoslof and over southern Unalaska Island. Cloud top temperatures seen in satellite data show that it rose to as high as 24,000 ft asl.

Another explosion occurred on August 27, at 15:08 AKDT (23:08 UTC), lasted about 2 minutes, and produced a cloud to 26,000 ft asl, drifting southeast. This explosion was followed by another at 3:23 AKDT August 28 (11:23 UTC), that lasted about 25 minutes and produced a very small eruption cloud that drifted east-southeast. This cloud dissipated quickly and was followed by another short explosive eruption at Bogoslof volcano beginning at 19:17 UTC (11:17 AKDT) August 28 and lasting about 2 minutes. No ash cloud was detected in satellite data.

An explosive eruption of Bogoslof volcano occurred August 30, 2017, beginning at 04:05 AKDT (12:05 UTC) and continued intermittently until about 05:55 AKDT (13:55 UTC). The eruption produced a low-level volcanic cloud that was observed in satellite data and produced at least one lightning strike. The cloud reached to about 20,000 feet above sea level and moved south, then dissipated over the southern Bering Sea - North Pacific Ocean area. AVO received no reports of ash fallout.

AVO has no ground-based volcano monitoring equipment on Bogoslof volcano and is unable to provide a forecast of future eruptive activity. We will monitor satellite images and data from distant seismic and infrasound instruments for indications of significant explosive activity.

The latest Bogoslof information is available at https://www.avo.alaska.edu/activity/Bogoslof.php

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URL: avo.alaska.edu/volcanoes/activity.php
Page modified: March 30, 2017 14:36
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