********************************************************************* ALASKA VOLCANO OBSERVATORY Weekly Update Friday, August 17, 2007 2:30 PM AKDT (2230 UTC) ********************************************************************* PAVLOF VOLCANO (CAVW#1102-03-) 55°24\'57\" N161°53\'24\" W, Summit Elevation 8261 ft (2518 m) Current Aviation Color Code: ORANGE Current Volcano Alert Level: Watch Pavlof Volcano, on the Alaska Peninsula, has been erupting since at least early Wednesday, August 15. AVO is maintaining aviation color code ORANGE and volcanic activity alert level WATCH at this time. Persistent earthquake activity and flow events, probably lahars (mudflows), continue at Pavlof Volcano. Several discrete explosion earthquakes have also been recorded. Though clouds obscured the volcano in satellite images Friday morning, one GOES satellite image shows that the large thermal feature from the summit eruption persists. These observations show that an eruption of lava at the surface is continuing. While a primary hazard from this eruption is airborne ash, explosions producing ash do not seem to be significant at this time. We have no evidence that ash has exceeded 10,000 ft asl and any ash produced is likely staying below 15,000 ft above sea level. The current episode began at approximately 9:30 UTC (01:30 AKDT) on Tuesday, August 14 with an abrupt increase in seismic activity. Based on the patterns of unrest leading to past eruptions at Pavlof, AVO raised the alert level and color code to ADVISORY / YELLOW on Tuesday afternoon. The rate of low frequency earthquakes steadily increased through Tuesday night. Strong thermal anomalies began to appear in AVHRR and GOES satellite data as early as 06:33UTC Wednesday, August 15 (22:33 AKDT Tuesday, August 14) and continued to be observed in all subsequent clear satellite views. AVO raised the alert level and color code to WATCH / ORANGE on Wednesday morning. Mariners offshore to the east and south observed incandescent blocks of lava tumbling down the east-southeast slopes and fire fountaining on the southeast side of the summit during the predawn hours Wednesday morning. Pilots reported that Pavlof was emitting ash with a plume extending as far as 8 km (5 mi) south-southeast of the summit at an altitude of about 2.6 km (8400 ft) later on Wednesday morning. They also reported that the normally snow-covered volcano was now covered with ash. Immediate hazards in the vicinity of the volcano include light ash fall on nearby communities, mudflows in drainages from the flanks of the volcano, and lava flows and avalanching of hot debris on the upper reaches of the volcano. 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 AVO continues to monitor the activity closely; satellite and seismic data are checked frequently around the clock. An AVO crew is enroute to Cold Bay to install additional monitoring equipment near the volcano. Pavlof volcano is a steep-sided, symmetrical, 8261-ft-high stratovolcano located on the southwestern end of the Alaska Peninsula about 590 miles southwest of Anchorage. The community of Cold Bay is located 37 miles to the southwest of Pavlof; Nelson Lagoon, King Cove, and Sand Point are other communities within 75 miles of the volcano. With almost 40 historic eruptions, it is one of the most active volcanoes in the Aleutian arc. Eruptive activity is generally characterized by sporadic lava fountaining continuing for a several-month period. Additional hazards in the vicinity of the volcano included light ash fall on nearby communities, mudflows, lava flows and avalanching of hot debris on the flanks of the volcano. For more information on Pavlof and potential volcano hazards, please see our web site: http://www.avo.alaska.edu/volcanoes/volcinfo.php?volcname=Pavlof ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
