Cleveland Activity - Color Code ORANGE : Alert Level WATCH

Based on reports from fishing boats Cleveland Volcano began erupting at approximately 12:00 AKDT (20:00 UTC) on July 21, 2008. This eruptive episode is more intense than that observed over the past several years. Pilot reports and satellite data have documented a persistent low level ash emission from 10,000 to 20,000 feet throughout the week when the volcano was visible through clouds. A large thermal anomaly suggests the presence of an ongoing active lava flow.

Reports from fishing boats indicate an eruption of Cleveland volcano occurred at approximately 12:00 AKDT (20:00 UTC). These reports indicate that at sea level the ash may be moving to the northwest. AVO has no information about the height of the ash cloud at this time.

Satellite and webcam views were mostly cloudy this week, though on July 14 and today thermal anomalies were visible at Cleveland's summit. AVO received no other reports of activity at Cleveland this week.

Cleveland was mostly obscured by clouds and fog in satellite and web camera images this past week, but occasional clear views show no signs of activity. The last observed ash cloud was on May 7 and a minor thermal anomaly was noted on June 8. AVO has received no reports of eruptive activity at the volcano.

Cloudy weather has obscured satellite and web camera views of Cleveland volcano all week. AVO has received no reports of eruptive activity at the volcano. The last observed ash cloud was on May 7 and a minor thermal anomaly was noted on June 8.

Cloudy weather has obscured web camera and satellite views of Cleveland all week. AVO has received no reports of eruptive activity at the volcano. The last observed ash cloud was on May 7 and a minor thermal anomaly was noted on June 8.

Cleveland has been hidden by clouds for most of the week. AVO received no reports of eruptive activity at the volcano. The last observed ash cloud was on May 7 and a minor thermal anomaly was noted on June 8.

Conditions have been mostly to partly cloudy at the volcano during the past week and no evidence of eruptive activity or ash clouds was observed. A minor thermal anomaly appeared in satellite images during the last 24 hours, with no other activity noted. Web camera views continue to show fog, with only an occasional brief glimpse of the lower flanks of the volcano. AVO has received no reports of ash emissions or other activity.

Clouds have obscured views of Cleveland Volcano by satellite and web camera over the past week. AVO has received no new reports of ash emissions or other activity.

Clouds have obscured views of the volcano by satellite and web camera throughout most of the past week, but no activity was observed during occasional clear periods. AVO has received no reports of ash clouds from Cleveland Volcano since May 7.

Clouds have obscured views of the volcano by satellite throughout the past week. AVO has received no reports of ash clouds from Cleveland Volcano since May 7. Recent ash emission (May 7) and thermal anomalies observed in the past several weeks, however, suggest that intermittent, low-level volcanic activity may be occurring at Cleveland. Recent eruptions of Cleveland Volcano have been characterized by moderate explosions at the volcano's summit and relatively small low-altitude ash clouds. The current level of activity is not unusual for this volcano. Intermittent clear satellite views of the volcano over the last several years suggest intermittent, small explosions are common but do not produce significant amounts of ash or debris. Therefore, AVO is currently holding the aviation color code at YELLOW and the volcano alert level at ADVISORY.

AVO has received no reports of ash clouds from Cleveland Volcano since Wednesday May 7. Satellite data provide no additional information, as clouds have obscured Cleveland Volcano throughout the past week. However, ash emission observed last week and thermal anomalies observed in the past several weeks suggest that intermittent low-level volcanic activity continues at Cleveland. Recent eruptions of Cleveland Volcano have been characterized by moderate explosions at the volcano's summit and relatively small low-altitude ash clouds. The current level of activity is not unusual for Cleveland Volcano. Intermittent clear satellite views of the volcano over the last several years suggest intermittent, small explosions are common but do not produce significant amounts of ash or debris. Therefore, AVO is currently holding the aviation color code at YELLOW and the volcano alert level at ADVISORY.

Over the past two weeks, an increasing number of thermal anomalies observed in satellite images suggests that unrest at Cleveland Volcano has intensified. A small, low-altitude (less than 15,000ft) discrete ash cloud was observed in satellite images beginning Wednesday evening from 4:00PM AKDT, May 7 (0000UTC, May 8) until about 11:00PM AKDT, May 7 (0700UTC, May 8). A ship north of Nikolski reported a dusting of ash around the same time. No other ash clouds have been observed since Wednesday night, but the volcano has been largely obscured by clouds. Wednesday’s ash cloud was likely a moderate explosion from the summit crater of Cleveland. Intermittent clear satellite views of the volcano over the last several years suggest intermittent, small explosions are common but do not produce significant amounts of ash or debris. The last ash cloud detected from Cleveland was on February 29, 2008. Th new ash cloud and more frequent thermal anomalies suggest that Cleveland may have entered a more active phase of activity with an increased possibility of additional explosions. However, this level of activity is not usual for Cleveland Volcano during the last several years. Therefore, AVO is currently holding the aviation color code at YELLOW and the volcano alert level at ADVISORY.

Thermal anomalies continued to appear in satellite data this week, indicating persistent low level volcanic activity at Cleveland Volcano. AVO has received no other information about activity at Cleveland during the past week.

Thermal anomalies observed in satellite data Tuesday and Thursday night indicate that low level volcanic activity continues at Cleveland Volcano. AVO has received no other information about activity at Cleveland during the past week.

Satellite views of Cleveland Volcano have been obscured by clouds. AVO has received no new information about activity at Cleveland during the past 24 hours.

Satellite views of Cleveland Volcano have been obscured by clouds over the past week and thus observations of the summit vent have been impossible. AVO has received no new information about activity at Cleveland during the past week.

AVO received no new information about activity at Cleveland throughout the week. Satellite views have been obscured by clouds all week, although a weak thermal anomaly was observed on Sunday, March 30.

Satellite views of Cleveland have been mostly cloudy this week. A weak thermal anomaly, however, was detected at the volcano's summit on March 27. AVO has received no other reports of activity at Cleveland this week.

Satellite views of Cleveland have been cloudy all week. A weak thermal anomaly was detected on March 15, otherwise AVO has received no other reports of activity at Cleveland this week.

Satellite views of Cleveland were cloudy throughout the past week. AVO has received no reports of activity at Cleveland this week.

On Tuesday at 6:20PM AKST, the National Weather Service relayed a pilot report of a minor ash cloud estimated to 5,000 feet above sea level in the vicinity of Cleveland. There were no corresponding observations of ash in satellite views. On Wednesday mostly clear satellite views showed a weak thermal anomaly. Satellite views were cloudy the rest of the week. AVO has received no additional reports of activity at Cleveland.

Satellite data showed a weak thermal anomaly at Cleveland on Sunday, February 23, 2008. For the rest of the week, clear to partly cloudy satellite views showed nothing unusual. AVO received no reports of activity at Cleveland this week.

Satellite images show that Cleveland volcano emitted a small ash cloud on Saturday, February 16 at approximately 0900 UTC (00:00 AKST). Based on satellite temperatures and tracking models, the ash cloud was likely below 4 km (13,120 ft). The ash cloud was first detected via satellite at 1247 UTC located about 96 km west-northwest of the volcano and continued moving WNW until 1741 UTC. No other activity has been observed or reported since the Saturday event.

A minor explosion late in the day on February 8th produced a small ash plume to 20,000 feet as reported by a pilot. Satellite data showed a plume extending northwest from the volcano at an estimated height of 16,000 ft. above sea level. AVO raised the Aviation Color Code to ORANGE and the Volcano Alert Level to Watch. The eruption was not sustained, and with no subsequent reports or evidence of further activity, AVO reduced the Color Code to YELLOW and the Alert Code to Advisory on February 12. Clouds have mostly obscured the volcano most of the week.

The minor eruptive activity at Cleveland late last week appears to have subsided and no further evidence of ash emission has been reported. Therefore, the Level of Concern Code is being reduced to Yellow and the Alert Code down to Advisory. Minor eruptive activity could continue at any time and AVO will continue to closely monitor the volcano.

Two pilot reports have been received of an eruption at Cleveland volcano at approximately 0120 UTC (16:30 AST). The plume was reported to be at 20,000 ft. above sea level. AVO sees a diffuse ash cloud extending northwest from the volcano. Clouds prevent us seeing if the plume has detached from the volcano. A diffuse low-level plume was also seen earlier in satellite data and would be consistent with an increase in activity. Thus, AVO is raising the Aviation color code to Orange and the Alert Level to Watch.

Cloudy weather obscured the volcano for most of the week with a break last night providing a brief satellite view of Cleveland emitting a diffuse, low-level (5,000 ft. or less) ash plume that extended up to about 12 km southeast of the volcano.

Clouds obscured views of Cleveland in satellite images most of the week. A weak thermal anomaly was detected on Tuesday, January 30. No indications of additional activity or thermal anomalies have been seen since that time. AVO has received no other reports of activity.<br /><br />

Clouds obscured views of Cleveland in satellite images most of the week. A weak thermal anomaly was detected on Saturday, January 20 yet no indications of additional activity or thermal anomalies have been seen in partially clear views since that time. AVO has received no other reports of activity.

A minor ash emission from Cleveland Volcano was detected in satellite data beginning around 2000 Z (12 :00 PM AST) on January 17, 2008. The short-lived event produced a small drifting ash cloud that moved towards the north. A precise height estimate could not be determined from the available data, but based on observations of previous ash emissions the cloud height was likely less than 10,000 ft (3048 m) above sea level. The drifting ash cloud was observed in satellite data for about four hours. A weak thermal anomaly was observed at the summit in several satellite images following the ash event. No further ash emissions have been observed since that time, but high clouds have moved into the region and have obscured the volcano. Small explosive events such as these are typical for Cleveland and do not necessarily indicate an increased potential for larger or more numerous events in the near future.

Satellite views of Cleveland Volcano remained cloudy throughout the week. AVO received no reports of activity at Cleveland.

Although clouds obscured Cleveland in satellite views for most of the past week, a couple of mostly clear views of the volcano showed no indications of activity. No reports of activity have been received.

Cloudy to partly cloudy satellite views of Cleveland showed nothing unusual this week. AVO received no reports of activity at Cleveland.

Partly cloudy to cloudy conditions obscured Cleveland in satellite views the past week and no indications of activity were observed. No reports of activity have been received.

Cloudy conditions have obscured Cleveland over the last week. AVO has detected no sign of continuing activity at the volcano.

Mostly cloudy conditions have obscured Cleveland during the past week and AVO has detected no sign of continuing activity at the volcano. The last weak thermal anomaly near the summit of the volcano was seen on November 20. AVO last noted a possible plume from Cleveland in late July.

Clouds have obscured the volcano all week, and observation by satellite has not been possible. AVO has received no new information about activity at Cleveland volcano over the past week.

Satellite views of the volcano have been most cloudy over the past week. Weak thermal anomalies have been observed in several satellite images during clear periods, but these are typical for the volcano at its current level of unrest. No other reports of activity have been received.

Satellite views were mostly cloudy this week, however a clear view on November 5 showed a weak thermal anomaly. AVO received no reports of activity this week.

Clouds obscured Cleveland volcano in satellite views this week. Nothing unusual was noted in satellite images and no reports of activity have been received.

Cloudy conditions prevailed for most of this week; however, on Monday, October 22, a one-pixel thermal anomaly was observed. No reports of activity have been received.

No activity was observed at Cleveland Volcano in mostly clear to partly cloudy satellite views this week. No reports of activity have been received.

Retrospective analysis of seismic data indicates that an explosion occurred at Cleveland at approximately 03:49 ADT (11:49 UTC) October 3, 2007. A thermal anomaly was detected in satellite data on October 7, 2007. Since then, nothing unusual has appeared in mostly cloudy satellite views.

No evidence of volcanic activity was noted in satellite imagery this past week. The AVO web camera is temporarily inoperative.

Clouds obscured views of the Cleveland Volcano by satellite this week and AVO received no new information about activity at Cleveland this week. The AVO web camera used for viewing Cleveland Volcano from Nikolski ceased functioning on Monday, Sept. 10.

Clouds obscured views of the volcano by web camera and satellite this week.

Clouds obscured views of the volcano by satellite and web camera most of the week. A partly clear satellite image from last night showed steaming and new snow at the summit of Cleveland. The temperature of the thermal anomaly in the crater has decreased. These data are consistent with our decision to decrease the aviation color code to yellow last week.

The Aviation Color Code was reduced to Yellow and the Volcano Alert Level was reduced to Advisory on Thursday of this week based on observations over several weeks suggesting that volcanic activity had decreased at Clevelend. The thermal anomaly had decreased in intensity and there had been no evidence of ash or gas plumes in satellite images since late July. Moreover, AVO received no reports of activity during this time period.

Satellite views were cloudy today. Web camera views were also cloudy.

Over the past several weeks, the thermal anomaly at Cleveland has decreased in intensity. There have been no observations of ash or gas plumes in satellite images since late July and AVO has received no reports of activity during this time period. These observations suggest that volcanic activity has decreased at Cleveland, thus, the Aviation Color Code is being reduced to Yellow and the Volcano Alert Level is reduced to Advisory.

Periodically throughout the week satellite views showed a persistent thermal anomaly at Cleveland's summit. Web camera views were cloudy all week.

Satellite and webcam views were predominantly cloudy all week, though on several occasions thermal anomalies were seen.

Photographs of a small burst of ash rising a few thousand feet above the summit of the volcano on July 20 (posted on the AVO web page http://www.avo.alaska.edu/) illustrate the kind of intermittent activity that is likely occurring. Based on previous historical eruptions of Cleveland, however, sudden explosions sending ash higher than 20,000 ft above sea level remain possible.

AVO continues to monitor the volcano closely with satellite imagery as weather allows. The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived explosions of ash that could exceed 20,000 ft above sea level can occur without warning and may go undetected on satellite imagery.

Clouds obscured satellite and webcam views of Cleveland all week. On Sunday, a commercial pilot observed that Cleveland was not steaming and showed no other signs of activity.

Photographs of a small burst of ash rising a few thousand feet above the summit of the volcano on July 20 (posted on the AVO web page http://www.avo.alaska.edu/) illustrate the kind of intermittent activity that is likely occurring. Based on previous historical eruptions of Cleveland, however, sudden explosions sending ash higher than 20,000 ft above sea level remain possible.

AVO continues to monitor the volcano closely with satellite imagery as weather allows. The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived explosions of ash that could exceed 20,000 ft above sea level can occur without warning and may go undetected on satellite imagery.

Occasionally visible thermal anomalies at Cleveland during the past week indicate that low-level eruptive activity continues. Photographs of a small burst of ash rising a few thousand feet above the summit of the volcano on July 20 (posted on the AVO web page http://www.avo.alaska.edu/) illustrate the kind of intermittent activity that is likely occurring. Based on previous historical eruptions of Cleveland, however, sudden explosions sending ash higher than 20,000 ft above sea level remain possible.

Intermittently visible thermal anomalies at Cleveland indicate that low-level eruptive activity continues. Photographs from July 27 and a pilot report from August 2 document fresh volcanic ejecta mantling the slopes and summit of the volcano. The east portion of Chuginadak Island was also dusted with ash.

No significant ash plumes have been observed during this recent episode of increased activity at Cleveland. However, a sudden explosion sending ash higher than 20,000 ft above sea level could still occur.

Persistent thermal anomalies have been detected in satellite data through the week indicating that that low-level eruptive activity continues. No steam or ash plumes have been observed but the possibility of an explosion sending an ash cloud to heights in excess of 20,000 ft above sea level remains. Three small SO2 clouds produced by small explosions on July 20, 2007 were detected in OMI satellite data provided by the University of Maryland Baltimore County. No further explosive activity has been detected by the OMI sensor since that time.

Weak thermal anomalies have been observed at Cleveland volcano in satellite images during periods of clear weather over the past month, and were thought to represent occasional low-level eruptive activity. A much more intense thermal anomaly and an associated steam and gas plume were observed on July 20, 2007 in a satellite image from 1525 UTC (0725 ADT). Although unconfirmed by visual reports, this increase in thermal activity is believed to indicate an increase in the intensity of eruptive activity. No ash emissions have been detected in satellite data since October 2006, but the possibility of an explosion sending an ash cloud to heights in excess of 20,000 ft above sea level has likely increased.

An intense thermal anomaly and an associated steam/gas plume were observed at Cleveland volcano this morning in a satellite image from 1525 UTC (0725 ADT), indicating that low-level eruptive activity is occuring. Thus, the aviation color code is being increased to Orange, and the volcano alert level is being increased to Watch. Although no ash has been detected in satellite data, the possibility of an explosion sending an ash cloud to heights in excess of 20,000 ft above sea level has increased.

Partly cloudy satellite views on July 12 showed a weak thermal anomaly but no evidence of ash or other deposits in the summit area. Clouds obscured the summit on other days during the week and AVO has received no additional information about activity at Cleveland Volcano.

Clear satellite views showed weak thermal anomalies at Cleveland volcano on July 3 and July 5. Satellite data showed no evidence of ash in the atmosphere however.

One partially cloudy satellite image from June 26 showed a thermal anomaly visible at Cleveland, suggestive of low-level eruptive activity. However, the satellite data showed no evidence of ash in the atmosphere. Since that time, no further thermal anomalies have appeared in satellite views, which have been persistently cloudy.

Two satellite images from June 17 showed a significant thermal anomaly visible at Cleveland through thick clouds, suggestive of low-level eruptive activity. However, the satellite data showed no evidence of ash in the atmosphere. Since that time, no further thermal anomalies have appeared in satellite views, which have been persistently cloudy.

AVO staff working in Nikolski this week could not see the volcano because of poor weather.

Steam emissions were observed in satellite data for approximately 12 hours on June 12, producing a plume that rose above a low cloud deck and extended for 125 miles (200 km) to the southeast. Pilots reported the height of the plume at approximately 12,000 ft (3.7 km) above sea level. Since that time, no further steam emissions have been observed in satellite data and recent clear satellite images show no sign of activity.

Clouds obscured views of the volcano by satellite this week. AVO has received no new information about unrest at Cleveland.

Clouds obscured views of the volcano by satellite this week. AVO has received no new information about unrest at Cleveland.

Clouds obscured views of the volcano by satellite this week and AVO has received no new information about unrest at Cleveland.

Clouds obscured views of the volcano by satellite most of the week. One possible thermal anomaly was observed Wednesday evening in AVHRR satellite data. AVO has received no new information about activity at Cleveland.

Clouds obscured views of the volcano by satellite all week. AVO has received no new information about activity at Cleveland.

Satellite views were cloudy throughout the week. AVO has received no other new information about activity at Cleveland.

Satellite views showed no activity at Cleveland this week. AVO has received no other new information about activity at Cleveland.

Other than a possible weak thermal anomaly early in the week, satellite views showed no activity.

Clear to partly cloudy satellite views through much of the week show no activity. AVO has no new information about activity at Cleveland.

Clouds obscured views of the volcano by satellite all week. AVO has no new information about activity at Cleveland.

Clouds obscured the volcano in satellite imagery for much of the week. AVO has no new information about activity at Cleveland.

Clouds obscured views of the volcano by satellite much of the past week. No unusual activity was observed in intermittent clear views and AVO has received no new information about activity at Cleveland.

Weak thermal anomalies have been observed at Cleveland during clear periods this past week. Based on past activity, it is likely that melting of snow near the summit has occured, producing small debris flows down the flanks of the volcano. Events such as these have occured over the past several years, and do not nessicarily indicate an increase in the potential for significant explosive activity. AVO did not receive any additional information concerning unrest at Cleveland this week.

Clouds obscured satellite views of Cleveland volcano most of the week, although a weak thermal anomaly was observed on Tuesday, March 6. AVO did not receive any additional information concerning unrest at Cleveland this week.

Clouds obscured satellite views of Cleveland volcano most of the week. Today mostly clear satellite views show no unusual activity. AVO did not receive any additional information concerning unrest at Cleveland this week.

On February 21, a two pixel thermal anomaly was seen at Cleveland's summit in satelite data. There is no clear evidence of ash emission or other erupive activity related to this thermal anomaly. No further indication of activity was seen in partly cloudy satelite images this morning.

Clouds obscured satellite views of Cleveland this week. AVO has received no new information about further unrest at Cleveland.

One partly cloudy satellite view showed a thermal anomaly at Cleveland on Wednesday night. Other cloudy to partly cloudy satellite views of Cleveland showed no other indications of activity this week. AVO has received no new information about further unrest at Cleveland.

Cloudy conditions have obscured views of the volcano by satellite this past week. AVO has received no new information about activity at Cleveland. Short-lived explosions with ash plumes that could exceed 20,000 ft above sea level can occur without warning and may go undetected on satellite imagery.

Cloudy conditions have obscured views of the volcano by satellite this past week. AVO has received no new information about activity at Cleveland. Short-lived explosions with ash plumes that could exceed 20,000 ft above sea level can occur without warning and may go undetected on satelite imagery.

Cloudy conditions have obscured views of the volcano by satellite this past week. AVO has received no new information about activity at Cleveland.

Cloudy conditions have obscured views of the volcano by satellite and web camera this past week. AVO has received no new information about activity at Cleveland.

The volcano was mostly obscured by clouds this past week, but nothing unusual was observed in satellite images during sporadic clear periods. AVO has received no new information about activity at Cleveland.

The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived ash explosions could occur without warning and may go undetected on satellite imagery.

The volcano was mostly obscured by clouds this past week, but nothing unusual was observed in satellite images during sporadic clear periods. AVO has received no new information about activity at Cleveland.

The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived ash explosions could occur without warning and may go undetected on satellite imagery.

Satellite views on Monday showed a weak thermal anomaly at Cleveland's summit, however the anomaly was not was seen in clear views of the volcano Tuesday. AVO received no new information or reports about activity at Cleveland this week.

Cloudy conditions obscured the volcano for most of the past week. AVO has received no new information about activity at Cleveland.

Cloudy conditions obscured the volcano this week. AVO has received no new information about activity at Cleveland.

AVO has received no new reports of ash eruptions at Cleveland. However, clouds have obscured the volcano for much of the week. Based on recent activity at the volcano, it is likely that low-level unrest continues. Ash explosions to 20,000 feet (6 km) above sea level or higher can occur with little or no warning. The most recent well-documented explosive activity was on October 28.

Over the past week there have been no new observations of ash emission. A thermal anomaly at the summit was observed today, but clouds have obscured the summit at other times during the week. Low-level unrest likely continues at Cleveland volcano and it remains possible for ash bursts to 10,000 feet above sea level or higher to occur with little or no warning.

Over the past week, there have been no new observations of ash emission or thermal anomalies. Clouds obscured satellite views of the volcano most of the week.

There have been no further observations of ash emissions from Cleveland since the brief explosive event on October 28 that produced an ash cloud which rose up to 6 km (20,000 ft) above sea level. A weak thermal anomaly has been observed in satellite images during clear periods this past week, as typically occurs following small eruptions of this volcano.

The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived ash explosions could occur without warning and may go undetected on satellite imagery. Should significant activity send ash above 20,000 feet, detection by satellite is more likely.

There have been no further observations of ash emissions from Cleveland since the brief explosive event on October 28 that produced an ash cloud which rose up to 6 km (20,000 ft) above sea level. A weak thermal anomaly has been observed in satellite images during clear periods this past week, as typically occurs following small eruptions of this volcano.

The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived ash explosions could occur without warning and may go undetected on satellite imagery. Should significant activity send ash above 20,000 feet, detection by satellite is more likely.

AVO is lowering the aviation color code to Yellow and the volcanic activity alert level to Advisory for Cleveland Volcano. There is no evidence of further activity at the volcano since the event on Oct. 28. Short-duration eruptions such as that event have been typical of Cleveland over the last several years. There is no seismic network on Cleveland; AVO monitors Cleveland chiefly by satellite.

AVO received a pilot report of an eruption of Mount Cleveland volcano at approximately 0000 UTC (1600 AKDT) today. Satellite data confirmed the presence of a drifting ash cloud moving ENE of the volcano. Based on satellite data, we estimate the height of the cloud to be 20,000 ft. above sea level, though one pilot report had it in excess of 30,000 ft. The eruption started at approximately 2345 UTC (1545 AKDT) and ended shortly thereafter.

AVO is raising the aviation color code to Orange and the volcanic activity alert level to Watch.

Short-duration eruptions such as this have been typical of Cleveland over the last several years. This is the fourth such known eruption this year, the previous one having occurred on August 24. There is no real-time seismic network on Cleveland; AVO monitors Cleveland chiefly by satellite.

Cloudy conditions obscured satellite views of Cleveland volcano for most of the week. No unusual activity was observed in partly clear views of the volcano.

The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived ash explosions could occur without warning and may go undetected on satellite imagery. Should significant activity send ash above 20,000 feet, detection by satellite is more likely.

Cloudy conditions obscured satellite views of Cleveland volcano for most of the week. No unusual activity was observed on partly clear views of the volcano.

The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived ash explosions could occur without warning and may go undetected on satellite imagery. Should significant activity send ash above 20,000 feet, detection by satellite is more likely.

Cloudy conditions obscured satellite views of Cleveland volcano for most of the week. On the one clear day, no unusual activity was observed.

Cleveland has been obscured by clouds during most of the past week, preventing satellite views of the volcano.

There is no real-time seismic network at Cleveland and AVO is unable to track local earthquake activity that may indicate volcanic unrest. Short-lived ash explosions may occur without warning and may go undetected on satellite imagery. Should significant activity send ash above 20,000 feet, detection by satellite is more likely.

Cleveland was obscured by clouds for most of the week. A few clear satellite views showed nothing unusual.

Cleveland volcano has produced brief, explosive eruptions sending ash clouds to elevations of 10,000 to 20,000 ft ASL on at least five occasions since February 2006 with the most recent confirmed explosion occurring on August 24, 2006. Additional short-lived, low-level ash explosions (less than 10,000 feet ASL) could continue intermittently for months or years.

There is no real-time seismic network at Cleveland and AVO is unable to track local earthquake activity that may indicate volcanic unrest. Short-lived ash explosions may occur without warning and may go undetected on satellite imagery. Should significant activity send ash above 20,000 feet, detection by satellite is more likely.

Cleveland was obscured by clouds for most of the week, but the few partly clear satellite views showed nothing unusual.

Cleveland volcano has produced brief, explosive eruptions sending ash clouds to elevations of 10,000 – 20,000 ft ASL on at least five occasions since February 2006 with the most recent confirmed explosion occurring on August 24, 2006. Additional short-lived, low-level ash explosions (less than 10,000 feet ASL) could continue intermittently for months or years.

Cleveland was obscured by clouds for most of the week, but the few clear satellite views showed nothing unusual.

Cleveland volcano has produced brief, explosive eruptions sending ash clouds to elevations of 10,000 – 20,000 ft ASL on at least five occasions since February 2006 with the most recent confirmed explosion occurring on August 24, 2006. Additional short-lived, low-level ash explosions (less than 10,000 feet ASL) could continue intermittently for months or years.

AVO monitors Cleveland using satellite images. There is no real-time seismic network on the island and AVO is unable to track local earthquake activity that may indicate volcanic unrest. Short-lived ash explosions may continue to occur without warning. Should a more significant ash explosion occur (greater than 20,000 feet ASL), detection by satellite analysis is more likely.

Yesterday, AVO announced a change in the level-of-concern color code for Cleveland volcano from unassigned to YELLOW based recent activity. Cleveland volcano has produced brief, explosive eruptions sending ash clouds to elevations of 10,000 –20,000 ft ASL on at least five occasions since February 2006 with the most recent confirmed explosion occurring on August 24, 2006. Additional short-lived, low-level ash explosions (<10,000 feet ASL) could continue intermittently for months or years.

Cleveland volcano does not have a real-time seismic network and therefore we are unable to monitor earthquake activity that may indicate volcanic unrest. The volcano is monitored, however, using satellite images. Frequent cloudy conditions and the small volume of ash clouds produced by these recent explosions, however, make them difficult to detect in satellite data. Larger events (>20,000 feet ASL) could also occur but are more likely to be detected by satellite. The current level of activity poses a hazard primarily to low-flying aircraft and to people on or within a few kilometers or few miles of the island.

A short-lived explosive eruption of Cleveland Volcano in the Central Aleutians occurred about 7:55 pm local time on August 24. This eruption was first reported by mariners on the evening of August 24; although unable to confirm this eruption using satellite data, the National Weather Service issued a one-time SIGMET to alert the aviation community.

On Monday, AVO received video footage of this eruption showing an ash cloud reaching about 10,000 feet ASL and ash fall occurring from the cloud. Additional video footage shows the volcano to be remarkably quiet within an hour of the explosion, with only minor steaming from the summit vent.

Cleveland Volcano has produced brief, explosive eruptions sending ash clouds to elevations of 10,000 – 20,000 ft ASL on at least five occasions since February 2006. Satellite images since the explosion on August 24 show a faint thermal anomaly at the summit, suggesting that unrest at the volcano continues, and further ash explosions are possible without warning. As a result, AVO is elevating the level of concern color code at Cleveland Volcano from unassigned to YELLOW. The current level of activity poses a hazard primarily to low-flying aircraft and to people on or within a few kilometers of the island.

Short-lived, low-level ash eruptions (<10,000 feet ASL), like that observed this past week, could continue intermittently for months to years. Frequent cloudy conditions and the small size of these ash clouds make them difficult to detect using satellite images. Larger events (>20,000 feet ASL), such as those in March and May, could also occur but are more likely to be detected by satellite. Cleveland volcano lacks a real-time seismic network and therefore we are unable to monitor seismic changes that reflect eruptive activity.

Just before 8:00 pm on August 24, the National Weather Service (NWS) received a report of an eruption at Mount Cleveland Volcano in the central Aleutians via a brief phone call from a passing ship. NWS and AVO scientists examined satellite images and seismic data from the closest stations (45 miles east of the volcano) and found no evidence of activity. Weather in the region is cloudy again today, but there is no indication of significant eruptive activity in the vicinity of Cleveland. Efforts to track down additional observation details from the ship have failed. Cleveland is not monitored directly with seismometers to detect volcanic earthquakes and explosions.

Frequently active Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. It is located about about 75 km (45 mi) west of the community of Nikolski, and 1500 km (940 mi) southwest of Anchorage. The volcano's most recent significant eruption began in February, 2001 producing 3 explosive events and ash clouds as high as 12 km (39,000 ft) above sea level. This eruption also produced a rubbly lava flow and hot avalanche that reached the sea. Short-lived explosions of ash reaching approximately 20,000 feet above sea level were observed on February 6 and May 23, 2006.