Printer friendly versionALASKA VOLCANO OBSERVATORY
Friday, September 7, 2007 4:40 PM AKDT (040 UTC)
55°24'57" N161°53'24" W, Summit Elevation 8261 ft (2518 m)
Current Aviation Color Code: ORANGE
Current Volcano Alert Level: Watch
The eruption of Pavlof Volcano that began August 15th continues. Seismicity this week has slightly declined from levels recorded last week but is still characterized by volcanic tremor, frequent explosions, and debris flow signals. Satellite observations throughout the week showed an intense thermal anomaly from continued lava production. No reports of ash plumes or plume heights were received this week.
If activity continues to increase, larger ash clouds that could affect higher-flying aircraft may be produced. The most immediate ground hazard in the vicinity of the volcano includes light ash fall on nearby communities. Previous historical eruptions from Pavlof caused only a few millimeters (about 1/10th of an inch) of ash to fall on King Cove, Nelson Lagoon, Cold Bay, and Sand Point. Mudflows in drainages from the flanks of the volcano, and lava flows and avalanching of hot debris on the upper reaches of the volcano are also of concern in the uninhabited areas around the volcano. Satellite and seismic data and eyewitness observations suggest most of the surface lava activity is occurring on the southeast sector of the steep-sided volcano; this suggests that the Pacific Ocean side of the volcano is at most risk from avalanching hot debris.
At this time, we expect this eruption to follow the pattern of previous eruptions. The last eruption of Pavlof began in September 1996 and consisted of a several-month-long series of ash explosions, lava-fountaining, and lava-flow production. Ash clouds reached as high as 30,000 ft asl on one occasion. However, most ash clouds were below 20,000 ft asl. Prior to 1996, Pavlof erupted in 1986 sending ash as high as 49,000 ft asl on at least one occasion. A hazard assessment for Pavlof and the Emmons Lake volcanic center is available on the web at http://www.avo.alaska.edu/pdfs/SIR2006-5248.pdf
Pavlof volcano is located on the southwestern end of the Alaska Peninsula. Pavlof is a stratovolcano which rises to an elevation of 8262 feet. With almost 40 historic eruptions, it is one of the most consistently active volcanos in the Aleutian arc. Eruptive activity is generally characterized by sporadic strombolian fountaining continuing for a several-month period. The community of Cold Bay is located 60 km (37 miles) to the southwest of Pavlof.
52°49'20" N169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Aviation Color Code: YELLOW
Current Volcano Alert Level: Advisory
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.
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.
KOROVIN VOLCANO (ATKA ISLAND)
52°22'48" N174°9'22" W, Summit Elevation 5030 ft (1533 m)
Current Aviation Color Code: GREEN
Current Volcano Alert Level: Normal
Earlier today, AVO lowered the Aviation Color Code to GREEN, and the Volcanic Activity Alert Level to Normal at Korovin. Over the last several months, seismicity rates have declined to near background levels. Recent satellite data also indicate that ground deformation at Korovin has slowed markedly, perhaps ceasing altogether, after a period of uplift from approximately mid-summer 2006 through early-spring 2007.
Steam emissions from Korovin and occasional bursts of low-level earthquakes or volcanic tremor may still occur, but both of these phenomena are typical of background activity for this volcano, which has a long-lived, well-developed hydrothermal system.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 31 volcanoes in Alaska. Satellite images of all Alaskan volcanoes are analyzed daily for evidence of ash plumes and elevated surface temperatures. Some volcanoes may currently display anomalous behavior but are not considered to be at a dangerous level of unrest. Wrangell, Spurr, Redoubt, Iliamna, Augustine, Fourpeaked, Snowy, Griggs, Katmai, Novarupta, Trident, Mageik, Martin, Peulik, Ukinrek Maars, Aniakchak, Veniaminof, Dutton, Isanotski, Shishaldin, Fisher, Westdahl, Akutan, Makushin, Okmok, Korovin, Great Sitkin, Kanaga, Tanaga, and Gareloi volcanoes are at Aviation Color Code GREEN and Volcano Alert Level NORMAL. All are at or near normal levels of background seismicity. AVO did not detect ash plumes or significant elevated surface temperatures in the vicinity of any volcano.
Please see http://www.avo.alaska.edu/color_codes.php for complete definitions of Aviation color codes and volcano alert levels.
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
Tom Murray, Scientist-in-Charge, USGS
email@example.com (907) 786-7497
Steve McNutt, Coordinating Scientist, UAF
firstname.lastname@example.org (907) 474-7131
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.