A long-term ground deformation change has been detected at the volcano by Global Navigation Satellite Systems (GNSS) stations during September and November.
On 20 March, AVO lowered the Volcano Alert Level for Okmok to Normal and the Aviation Color Code to Green. Seismic activity had been at low to near background levels and satellite views showed no activity during the previous two weeks. The last confirmed ash emission at Okmok occurred on 19 August 2008.
Tue, 10 Mar 2009, 13:07
The AVO raised the level of danger to the color code Yellow, because of increased seismicity. A eruption in near future is possible.
Wed, 25 Feb 2009, 06:00
On 2 March, AVO raised the Volcano Alert Level for Okmok to Advisory and the Aviation Color Code to Yellow because of increased seismicity. Short bursts of volcanic tremor at an average rate of one per hour had been detected during the previous 24 hours, an increase above the typical background level. The events were the first sign of significant seismic activity at the volcano since the cessation of the last eruption in August 2008.
Read allWed, 27 Aug 2008, 06:00
On 27 August, AVO lowered the Volcano Alert Level for Okmok to Advisory and the Aviation Color Code to Yellow because seismicity had declined steadily during 20-27 August and ash plumes had not been observed since 19 August. On 28 August, a thermal anomaly and a steam plume were detected on satellite imagery. Cloud cover prevented observations on the other days.
Read allThu, 21 Aug 2008, 17:39
AVO reported that on 13 August low-level steam-and-ash plumes from Okmok were visible on satellite imagery drifting SE at altitudes of 3-4.6 km (10,000-15,000 ft) a.s.l. During 14-17 August satellite observations were hindered due to cloud cover; seismic levels fluctuated possibly indicating that steam-and-ash emissions continued. During 18-19 August, ash plumes were seen on satellite imagery at altitudes of 3-4.6 km (5,000-15,000 ft) a.s.l. The Volcano Alert Level remained at Watch and the Aviation Color Code at Orange.
Wed, 20 Aug 2008, 06:00
AVO reported that seismic activity at Okmok decreased on 19 August to near pre-eruption levels and remained low during 20-24 August. Occasional bursts of volcanic tremor were detected. Although satellite views were hindered due to cloud cover, a possible thermal anomaly in the crater was present on 21, 24, and 25 August.
Read allWed, 13 Aug 2008, 06:00
AVO reported that on 13 August low-level steam-and-ash plumes from Okmok were visible on satellite imagery drifting SE at altitudes of 3-4.6 km (10,000-15,000 ft) a.s.l. During 14-17 August satellite observations were hindered due to cloud cover; seismic levels fluctuated possibly indicating that steam-and-ash emissions continued. During 18-19 August, ash plumes were seen on satellite imagery at altitudes of 3-4.6 km (5,000-15,000 ft) a.s.l.
Read allWed, 6 Aug 2008, 06:00
AVO scientists observed the eruption of Okmok during a visit to Umnak Island on 2 and 3 August. They saw significant ashfall that had accumulated in the caldera and on the upper flanks, lahars and lahar deltas that formed in drainages from the SE to the NE flank, and continuous ash jets being emitted from three or more vents in the vicinity of Cone D in the NE sector of the caldera. Elevated seismicity was detected during 6-8 August, and declined on 9 August.
Read allTue, 5 Aug 2008, 11:10
View of Okmok's ash plume emitting from multiple vents near intracaldera Cone D, taken at about 1:30 pm on August 3, 2008 by Jessica Larsen.
Ash emissions emitting plumes reaching several kilometers height continue at Okmok volcano.
Wed, 30 Jul 2008, 06:00
Based on observations of satellite imagery and pilot reports, AVO reported that ash plumes from Okmok rose to altitudes of 4.6-10.7 km (15,000-35,000 ft) a.s.l. and drifted SW, W, N, NNE, and SE. On 30 July, seismicity alternated between continuous and pulsating volcanic tremor.
Read allThu, 24 Jul 2008, 12:27
On
19 July, activity at Okmok increased as interpreted from seismicity. Possibly, ash plumes rose to altitudes of 7.6-9.1 km (25,000-30,000 ft) a.s.l. The Volcano Alert Level was raised to Warning and the Aviation Color Code was raised to Red.
Read allWed, 23 Jul 2008, 06:00
AVO reported that on 23 July, seismicity from Okmok changed from episodic volcanic tremor to nearly continuous mid-level volcanic tremor. Although cloud cover obscured views of Okmok, previously emitted ash plumes were observed to the ESE. On 24 July, a thermal anomaly was possibly present on satellite imagery.
Read allWed, 16 Jul 2008, 07:11
image showing the extent of the sulfur dioxide gas cloud from the eruption of Okmok Volcano. The large red mass is from the main explosive phase on 12 July at 2130 UTC and is at an estimated height of 50,000 ft above sea level. The north-south dimension of this cloud is about 850 miles. Current emissions from the volcano are at a lower altitude of approximately 30,000 to 35,000 feet. Other OMI data (not shown) indicate that volcanic ash is mixed with the sulfur dioxide cloud.
Okmok Volcano continues to erupt. Seismicity, though below this weekend's intensity, has remained steady over the last 24 hours. Satellite data continue to show a long (~250 km) plume moving east; the height of the plume is approximately 30,000 ft above sea level.
Wed, 16 Jul 2008, 06:00
AVO reported that during 15-16 July seismicity from Okmok changed from nearly continuous to episodic volcanic tremor, and the overall seismic intensity declined. Satellite imagery indicated elevated surface temperatures in the NE sector of the caldera; meteorological clouds obscured views. On 16 July, the Volcano Alert Level was lowered to Watch and the Aviation Color Code was lowered to Orange.
Read allMon, 14 Jul 2008, 12:09
The strong eruption at Okmok continues based on ongoing seismic activity and satellite observations. Ash emissions continue reaching altitudes of 30,000 - 35,000 ft asl, and are posing a large hazard to all aircraft in the area.
Sun, 13 Jul 2008, 07:02
A large explosive eruption at Okmok volcano began at approximately 11:43 AM local time on July 12 and continues. An ash cloud with a top of at least 30,000-35,000 ft. height above sea level is present.
Read allWed, 9 Jul 2008, 06:00
A strong explosive eruption at Okmok began abruptly at 1143 on 12 July after about an hour of rapidly escalating earthquake activity. Ash and gas from the initial explosions reached at least 15 km (50,000 ft) a.s.l on 12 July and drifted as a large cloud S and E above the North Pacific. Satellite tracking of the ash cloud by traditional techniques has been hampered by the high water content due to interaction of rising magma with very shallow groundwater and surficial water inside the caldera.
Read allWed, 16 May 2001, 06:00
AVO reported that the earthquake swarm centered near Okmok that was first detected on 11 May greatly diminished by 15 May.
Read allWed, 9 May 2001, 06:00
During ~0800 to at least 1700 on 11 May AVO detected a small earthquake swarm that was centered near Okmok. Earthquakes in the swarm had magnitudes of approximately 2-3.6, but their locations could not be pinpointed because Okmok is not monitored by a local seismic network. AVO noted that the earthquakes may have been of volcanic origin, but earthquake swarms with similar sizes and character are not uncommon at Aleutian arc volcanoes and do not necessarily lead to eruptive activity.
Read all