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Trident seismicity information statement July 25, 2023 Notice: Planned Maintenance and Power Downs at Butrovich Data Center - Website Service Outage Alaska Volcano Observatory Sitka visit May 5-9, 2023 Get to know Makushin Volcano AVO Information Statement on Sheveluch Volcano, April 13, 2023

Currently active Mount Cerberus volcano now named Mount Young  33rd anniversary of Redoubt's 1989-1990 eruption Where did the Mystery Ash come from? Maybe YOU have the answer! No volcanic gases detected at Mt. Edgecumbe during recent survey. Mt. Edgecumbe gets a new monitoring station Mount Edgecumbe volcanic field changes from "dormant" to "active" -- what does that mean? Mount Edgecumbe Information Statement, April 22, 2022

Meet the Atka Volcanic Complex Resuspended ash from Aniakchak: August 2, 2021 Information Statement 90th Anniversary of the 1931 eruption of Aniakchak Volcano, Alaska Booming sounds from Veniaminof and their source AVO assists in multi-agency effort to monitor the Barry Arm Landslide in Prince William Sound AVO's 2020 Field Season

Alaska Volcano Observatory Expands Eruption Detection Capability in Cook Inlet The Alaska Volcano Observatory’s summer 2020 field work plans Update on AVO Operations during COVID-19

AVO announces extensive upgrades to volcano monitoring equipment during summer 2019 fieldwork New publication: Alaska Volcano Observatory geochemical database, version 2 New publication: On the eruption age and provenance of the Old Crow tephra New publication: Historically active volcanoes of Alaska v. 3

In the event of a federal government shutdown Tectonic earthquakes and Alaska volcanoes Volcanic Threat Assessment helps prioritize risk reduction efforts at U.S. volcanoes AVO hiring a software engineer at University of Alaska Fairbanks Geophysical Institute Happy 30th Birthday, AVO! New publication: Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska New publication: Geochemistry of some Quaternary lavas from the Aleutian Arc and Mt. Wrangell New publication: Geologic map of Chiginagak volcano New publication: Major-element glass compositions of tephra from the circa 3.6 ka eruption of Aniakchak volcano, Alaska Peninsula, Alaska New publication: The 2014 eruptions of Pavlof Volcano, Alaska New publication: Historically active volcanoes of Alaska reference deck, v.2

Bogoslof Volcano, Alaska: ongoing eruption through the Bering Sea 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, through 19 January 2017
Posted: January 04, 2017
Summary of current activity, as of January 19, 2017

Explosions have altered Bogoslof Island. Figure from 18 Jan 2017 data
Bogoslof volcano is in an active eruption sequence that began on December 16, though retrospective analysis suggests unrest may have started earlier in December. Eruptive activity has been dominated by a series of explosive events lasting from about 30 to 60 minutes each. These explosions have occurred on December 16, 19, 20, 21, 23, 26, 28, 30, January 2, 3, 5, 8, 12, 15, 17, and 18 (local time). The intensities of these explosions have varied. Eruptions on December 21 and 26 produced water-rich and relatively ash-poor volcanic clouds that rose as high as 10.7 km (35,000 ft) above sea level and were tracked in satellite images as they were transported with the prevailing winds. Sulfur dioxide gas clouds from many of these events have been detected in satellite data, and the event on December 21 was tracked in satellite data for five days to a location over the central United States (Nebraska). Pilots reported that the January 18 (13:20 AKST; 22:20 UTC) ash cloud reached a height greater than 9.5 km (31,000 ft) above sea level. Satellite observations just after the January 18 (13:20 AKST; 22:20 UTC) event showed an ash cloud darker in color, and presumably more ash-rich, than others in this eruptive sequence, suggesting the presence of very hot material (lava) at the surface immediately surrounding the vent - the first such observation during this eruption sequence. The Alaska Dispatch News reported that the January 18 ash cloud affected at least three of four flights at a minimum (https://www.adn.com/alaska-news/aviation/2017/01/19/another-bogoslof-eruption-sends-ash-over-alaska-peninsula-kodiak-island/).

We have had very few direct observations of the activity at Bogoslof due to its remote location, cloud cover, and limited daylight hours. The event on December 20 was observed by pilots, who saw an ash plume rising out of the ocean. During the December 23 event, observers aboard a Coast Guard vessel reported ash emission, lightning, and the ejection of incandescent lava and fragmental material.

High-spatial-resolution satellite images show that the explosions have dramatically altered Bogoslof Island (http://www.avo.alaska.edu/images/image.php?id=103521). A new vent has developed at the northeast end of the island, immediately offshore. Explosions have formed a new cone of fragmental rock and ash, and portions of the old island have been destroyed. The location of the vent in shallow seawater has produced water-rich eruption clouds that are characterized by abundant lightning (due to ice formation in the cloud). The clouds are also relatively dispersed and ash poor due to enhanced removal of volcanic ash near the vent.

Monitoring Status
Bogoslof is not monitored by a local, on-island geophysical network, which limits our ability to forecast activity at this volcano. AVO is using seismic and infrasound (pressure) sensors from Okmok and Makushin volcanoes on neighboring Umnak and Unalaska Islands to monitor activity, as well as more distant infrasound sensors in Dillingham and Sand Point. Due to the distance from Bogoslof, these sensors can detect signals produced by large explosive events, but they are not sensitive enough to detect lower-level signals that could help forecast imminent eruptions. 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. In addition, storms are common in the Aleutians during this time of year, and seismic and infrasound signals are often masked by wind-generated noise.

Near-real-time satellite data are being used to detect explosive eruptions, to estimate volcanic cloud height and to track the dispersion of the resulting volcanic clouds. These data can also detect highly elevated surface temperatures from lava effusion or hot ash deposits, but none have been observed to date. Data from the World Wide Lightning Location Network provide near-real-time automated alerts of lightning strikes near Bogoslof that have been shown to be indicative of explosive activity at the volcano.

AVO will continue to provide timely warnings of activity to the best of our ability and will issue Volcanic Activity Notices (VANs) and Volcanic Observatory Notices for Aviation (VONAs) as needed.

Prognosis and Hazards
On the basis of previous historical eruptions of Bogoslof, we can expect that episodic explosions emitting ash to flight levels could occur for days to weeks during this current period of unrest. It is likely, but not certain, that the current eruption will follow a pattern similar to other historical eruptions. There is no indication at this time that current activity is building to a significantly larger eruption.

If the eruption continues, it is possible that a new cone of rock and ash will continue to grow and rise above sea level. If future eruptions occur above water, the resulting ash clouds may be less ice-rich, which could result in less lightning, decreasing AVO’s ability to quickly detect the presence of an ash cloud. Such eruptions could also become more ash-rich than the previous eruption clouds without significant interaction with seawater that increases ash removal. If this occurs the probability of ash fall on neighboring communities (Nikolski, Unalaska, Akutan) may increase. AVO provides model outputs that predict ash fall and ash cloud information based on either hypothetical or actual eruption information on our website’s Bogoslof Activity Page (https://www.avo.alaska.edu/activity/Bogoslof.php). For official forecasts of ash cloud movement or ash fall, however, we refer you to the Alaska Aviation Weather Unit or the National Weather Service forecast office.


Bogoslof index map
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, as well as the growth of lava domes.
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