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Thank you Unalaska! Bogoslof Summary of Current Activity Bogoslof Summary of Current Activity, through 19 January 2017

AVO studies resuspended volcanic ash from the Katmai region to Kodiak Island, Alaska Citizen Science - Volcanic Ash Collection Workshop and Public Talk, Kodiak January 30, 2016 Fieldwork at Iliamna and Spurr New publication highlights the importance of ash scrubbing in the evaluation of hazards from explosive eruptions

Critical Volcano Monitoring Systems Returned to Operation in Alaska Resuspended Volcanic Ash from the Katmai Region to Kodiak Island Remobilized Katmai 1912 ash: community events and health hazard analysis Makushin 2015 Geology Blog Sixth Anniversary of the Redoubt 2009 Eruption Happy Anniversary, Shishaldin 1967 and 2014!

New Publication on Aniakchak Volcano Available Online 25th Anniversary of the 1989-90 Eruption of Redoubt Volcano AVO geochemical database now available AVO Scientists Discuss Cook Inlet Volcanoes on Frontier Scientists TV Series Announcing new monitoring equipment for Cleveland volcano 22nd anniversary of Crater Peak (Mt Spurr) June 27 eruption Revised Alaska Interagency Operating Plan for Volcanic Ash Episodes Anniversary of Aniakchak 1931 eruption! April 19th - anniversary of Shishaldin 1999 and Pavlof 1986! Ground-coupled airwaves and explosion signals at Shishaldin 5th anniversary of the Redoubt 2009 eruption Loss of Critical Volcano Monitoring Information in Alaska NEW VOLCANO NUMBERING SYSTEM IMPLEMENTED Loss of Critical Volcano Monitoring Information in Alaska Report released: Geochemical investigations of the hydrothermal system on Akutan Island, July 2012

24th Anniversary of the 1989-90 eruption of Redoubt Volcano Veterans Day slideshow Call for images from active and retired service members! AVO operations during lapse of federal government appropriations New Tool for Reporting Alaska Volcanic Ash Fall Allows Residents to Assist Scientific Monitoring 25 years monitoring Alaska volcanoes - press release

AVO slideshow for Veterans Day Large ash eruptions: when volcanoes reshape valleys -- free public lecture Father Hubbard and the history of exploration in the Valley of Ten Thousand Smokes - free lecture Remote sensing and volcanoes - free public lecture The Great Eruption of 1912 - free public lecture Infrasound Detection of Volcanic Explosions Archaeology of Katmai area and the impact of past eruptions - free public lecture Historical Photography of the Great 1912 Eruption - free public lecture Catastrophic Eruptions and People -- free public lecture Eruption of an Island Volcano: Kasatochi, 2008 -- free public lecture Exploring the Plumbing System of Katmai Volcanoes Exploration of Katmai and the Valley of Ten Thousand Smokes - free public lecture Commemorative presentation in Kodiak: Be Prepared! Earthquakes Below Alaskan Volcanoes - free public lecture DisaStory - A Day of Oral History 1912 Katmai Eruption Children's Program Monitoring Alaska's Volcanoes - free public lecture Landmark volcano study: Katmai Centennial Perspectives free download Special activities on AVO's website for 1912 centennial Alaska Park Science - Volcanoes of Katmai and the Alaska Peninsula AVO at the Alaska Aviation Trade Show and Conference May 5-6 The Great Katmai Eruption of 1912 - a free lecture in Anchorage: April 24, 2012 The Great Katmai Eruption of 1912: A Century of Research Tracks Progress in Volcano Science April 25 -- The Novarupta - Katmai 1912 eruption: a free lecture in Fairbanks by Judy Fierstein Summer lecture series on Alaskan volcanism Poster contest celebrates anniversary of Katmai eruption! Mark your calendar: April 24 public lecture on the great Novarupta-Katmai eruption of 1912 An important volcanic anniversary in Alaska! PUBLISHED: The 2009 Eruption of Redoubt Volcano, Alaska

2011 Alaska Interagency Operating Plan for Volcanic Ash Episodes now available How does Cleveland's lava dome compare to Redoubt's 2009 lava dome? Alaska Volcanoes Guidebook for Teachers

New Fact Sheet on Kasatochi How big is the 2009 Redoubt lava dome?

New map: Historically active volcanoes of Alaska Steaming at Augustine Sarychev Volcano: Active Volcanoes of the Kurile Islands Footage of Alaska's Redoubt Volcano taken on Monday, March 23, 2009. Pre-eruption footage of Redoubt Volcano, Saturday, March 20, 2009 Redoubt Volcano B-Roll Footage

Kasatochi 2008 eruption summary 6th Biennial Workshop on Subduction Processes emphasizing the Kurile-Kamchatka-Aleutian Arcs Geophysical Institute, University of Alaska, Fairbanks, Alaska Chiginagak volcano's acid crater-lake continues to supply acidic, metal-laden water to salmon spawning habitat on the Alaska Peninsula ALASKA VOLCANOES - TEACHER ACTIVITY GUIDEBOOK & KIT 20 years of AVO Viewing earthquake information for Alaska volcanoes

Pavlof webcam added Activity at Pavlof volcano Pavlof thermal anomaly AVO Scientists present at U.S. Department of Education Teacher-to-Teacher Workshop Cleveland webcam available Activity at Cleveland volcano Cleveland satellite images Sheveluch Eruption U.S. Geological Survey's alert notification system for volcanic activity KVERT Volcanic Warnings Ceased

New alert system for volcanic activity Three new webcams added AGU presentations requested New webcam available
Bogoslof Summary of Current Activity
Posted: January 31, 2017
Summary of current activity, as of January 31, 2017

Bogoslof shoreline change, 31 Jan 2017
Bogoslof volcano is in an active eruption sequence that began on December 12, 2016. Until recently, eruptive activity detected by remote monitoring instruments, in satellite data, and from pilot reports had been dominated by a series of short-duration (minutes to tens of minutes) explosive events. There were about 27 such events, occurring every 1 to 4 days. The resulting volcanic clouds rose to altitudes of 20,000 to 35,000 ft above sea level, and were typically discernible in satellite images for hours afterwards. Most of the clouds were ice-rich, due to the influx of seawater into the eruption column, but likely contained volcanic ash as well. Sulfur dioxide (SO2) gas clouds from some of these events were detected in satellite data, and the cloud from the December 21 event was tracked by satellite for five days to a location over the central United States (Nebraska).

Most recently, explosive ash emissions through the night of January 30-31 were more continuous in nature and produced an ash cloud to about 25,000 ft asl. The ash cloud was transported to the southeast over Unalaska Island and resulted in a trace amount of ash fallout in Unalaska/Dutch Harbor. This was the first such ashfall reported during the eruptive sequence.

Satellite images from today, January 31, show significant changes at Bogoslof Island. Whereas previous explosive events in this sequence had issued from a vent in shallow seawater, freshly erupted volcanic rock and ash have formed a barrier that separates the vent from the sea for the first time since the eruptive sequence began. As a result, we infer that this change has resulted in the more ash-rich emissions that occurred during the evening of January 30 to 31 (AKST).

A previous satellite image, from January 24, shows that the explosive eruptions to that time had significantly changed the shape and coastline of the island. On that date, the eruptive vent remained below sea level, most likely in the northern portion of a figure-eight-shaped bay, where upwelling volcanic gases were observed.

Only the strongest eruptive events are being detected by our monitoring network. It is likely that lower level, but still hazardous phenomena are occurring at the volcano during times when the volcano appears quiet on distant instruments.

Monitoring Status
Bogoslof is not monitored by a local, on-island geophysical network, which limits our ability to detect unrest and forecast activity at this volcano. AVO is using seismic sensors from Okmok (32 mi, or 50 km) and Makushin (45 mi, or 72 km) volcanoes on neighboring Umnak and Unalaska Islands to monitor activity. Since the eruption began, patterns in seismicity prior to some significant explosive events have allowed AVO to provide some forecasts, whereas other explosions have occurred with no detectable precursors. Storms are common in the Aleutians during this time of year, and seismic signals are often masked by wind-generated noise.

In addition to seismicity, explosive volcanic activity also produces infrasound signals (pressure waves) that we can detect on sensors at Okmok volcano on neighboring Umnak Island, as well as more distant infrasound sensors in Dillingham and Sand Point. Since the pressure waves move at the speed of sound, there is a delay of tens of minutes between eruption onset and detection at distant infrasound sensors. As with seismic signals, storm noise can also mask explosions in infrasound data.

Data from the World Wide Lightning Location Network provide near-real-time (within minutes) automated alerts of lightning strokes near Bogoslof that have been shown to be indicative of explosive activity at the volcano. Thus far, 18 of 28 explosive events have had associated lightning strokes.

AVO uses near-real-time satellite data to detect explosive eruptions, to estimate volcanic cloud height and to track the dispersion of the resulting volcanic clouds. Although we can detect energetic explosive activity in real-time, there is typically a lag of tens of minutes until we can characterize the magnitude of the event and the altitude of the volcanic cloud. These data can also detect highly elevated surface temperatures from lava effusion, the presence of a lava dome, or hot ash deposits. Heavy weather-cloud cover can obscure observations of volcanic activity in satellite data.

AVO will continue to provide timely warnings of activity given the constraints of the current monitoring data sources and will issue Volcanic Activity Notices (VANs) and Volcanic Observatory Notices for Aviation (VONAs) as needed.

On the basis of previous historical eruptions of Bogoslof, we can expect that episodic explosions, emitting ash-bearing volcanic clouds that reach 20,000 ft asl or higher, could continue for weeks or more. It is likely, but not certain, that the current eruption will continue to follow the pattern of other historical eruptions. Eventually a lava dome may be extruded at the surface. There is no indication at this time that current activity is building to a significantly larger eruption.

The shift in activity that occurred overnight January 30-31 was coincident with the growth of the new subaerial (above sea level) cone. This shift could result in some changes in the character of the eruption, as the extent of magma interaction with seawater will be reduced. Future explosive eruptions may become more ash-rich without the scrubbing effects of seawater. The probability of ashfall on neighboring communities (Nikolski, Unalaska, Akutan) may increase, depending on wind direction.

Continued volcanic activity, combined with erosion from wave action, likely will modify the island further. In this dynamic environment, the vent may sometimes be above, and sometimes below, sea level. The nature of future volcanic activity may shift accordingly, perhaps switching between short events with ice-rich clouds to longer, more ash-rich events.

The main hazards associated with the current eruption are from volcanic clouds. Airborne ash is a significant hazard to aircraft. During specific explosive events, official forecasts of ash-cloud movement can be found at the Alaska Aviation Weather Unit. Additionally, the Federal Aviation Administration (FAA) currently has issued a Temporary Flight Restriction (TFR) around Bogoslof that will remain in effect while the volcano is in eruption.

The potential for ashfall on local communities depends upon wind direction, eruption intensity and the mass of ash that is produced during each explosive episode. Ashfall was reported on Unalaska Island during eruptions in 1883-85, 1890, and 1906-07. The explosive eruptions of January 30-31 were the first events in the current sequence to produce trace ashfall on Unalaska/Dutch Harbor. AVO provides model outputs that predict ash fall and ash cloud information based on either hypothetical or actual eruption information on our website. Official forecasts of ashfall can be found at the National Weather Service Forecast Office website.

In addition to the hazards mentioned above, local hazards in the vicinity of Bogoslof can be severe during individual explosive events and may be present at other times though not detectable by our monitoring techniques. These include base surges, which are ring-shaped clouds of gas and suspended solid debris that move radially and rapidly outward from the vent area, hugging the ocean surface. Although we have not observed base surges directly, the landforms produced during this sequence suggest that surges have occurred. Based on studies at other volcanoes, it is possible for these flows to travel 4 miles (6 km) or more from the eruption site. Thus a reasonable hazard zone for base surges is 6 miles (10 km) beyond the volcano in all directions. The Coast Guard is issuing a Local Notice to Mariners in District 17 regarding the proximal hazards around Bogoslof Island (https://www.navcen.uscg.gov/?pageName=lnmMain).

Explosive disturbance of the ocean around the eruption site is likely displacing seawater and may be generating small waves. So far, such waves do not appear to be large or far-traveling and do not pose a significant hazard.

Bogoslof Island is the largest of a cluster of small, low-lying islands making up the summit of a large submarine stratovolcano. The highest point above sea level prior to this eruption was about 100 m (300 ft); however, the volcano is frequently altered by both eruptions and wave erosion and has undergone dramatic changes in historical time. The two main islands currently above sea level are Fire Island and Bogoslof Island, both located about 98 km (61 mi) northwest of Unalaska/Dutch Harbor, 123 km (76 mi) northeast of Nikolski, and 149 km (93 mi) northeast of Akutan. The volcano is situated slightly north (behind) the main Aleutian volcanic front. Bogoslof volcano is within the U.S. Fish and Wildlife Service Alaska Maritime National Wildlife Refuge and is habitat for marine mammals and seabirds.

At least 8 historical eruptions have been documented at Bogoslof. The most recent occurred from July 6 to 24, 1992, and produced episodic steam and ash emissions including an ash cloud up to 8 km (26,000 ft) above sea level and an extrusion of a 150 m (500 ft) by 275 m (900 ft) lava dome on the north end of the island. Previous eruptions of the volcano have lasted weeks to months, and have on occasion produced ash fall on the community of Unalaska. Eruptions of the volcano are often characterized by multiple explosive, ash-producing events such as we have seen in 2016 and 2017, as well as the growth of lava domes.
URL: avo.alaska.edu/news.php
Page modified: December 2, 2016 10:12
Contact Information: AVO Web Team

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