Volcano Watch — Bogoslof Volcano, Alaska: ongoing eruption through the Bering Sea
Let’s go north to Alaska where scientists have been tracking an intermittent eruption of lava through water surrounding a small island volcano in the southern Bering Sea. On December 21, 2016, the volcano burst to life sending clouds of ash and water vapor towering into the sky. Pilots were the first to see the eruption, calling in reports to air traffic control. Soon, scientists with the Alaska Volcano Observatory and the National Weather Service saw the eruption cloud on satellite imagery. Using information about winds aloft, warnings of the forecast ash cloud path went out to airlines.
This volcano is called Bogoslof, a Russian name given in 1796 to a small cluster of volcanic rocks about 60 miles west of the city of Unalaska, a major fishing community in the Aleutian Islands. These islets are the summit of a submarine volcano that peeks just above the ocean surface.
The 2016-2017 eruption so far has included more than 30 explosions lasting minutes to hours have alternating with periods of quiet. Early explosions were ice-rich reflecting large amounts of seawater incorporated into the eruption clouds. Sulfur dioxide from one of these explosions was tracked by satellite as far away as Nebraska! By late January 2017, eruption clouds became enriched in ash as the eruptive vent became more isolated from seawater. Winds took an eruption cloud over Unalaska where residents experienced a dusting of ash.
The intermittent eruption dramatically changed the shape of the island as explosion debris accumulated above sea level only to be eroded by wave action in subsequent days. What had been an oasis for countless seabirds, sea-lions, and (Pacific Northern) fur seals – part of the U.S. Fish and Wildlife Service’s Alaska Maritime National Wildlife Refuge – is now an ash-covered moonscape surrounding a turbid (and acidic) lagoon.
Bogoslof Volcano is far from Hawaii but not far from our institutional history. In 1907, Hawaiian Volcano Observatory founder Thomas A. Jaggar sailed to this very island volcano in Alaska on an expedition from the Massachusetts Institute of Technology. Their objectives, to explore Alaska’s volcanoes and search for mineral deposits, led to a report on the evolution of Bogoslof published in the Bulletin of the American Geographical Society in July 1908.
Jaggar was a keen observer and his notes on Bogoslof chronicle the record of eruptive activity summarized by mariners in the century leading up to 1907. Using these data and observations from his own several hours exploring the island, Jaggar compiled a sequence of maps of the changing island in a manner very similar to Alaska Volcano Observatory geologists today.
He also surmised the mechanism of Bogoslof eruptions and found similarities in the extrusive lava formations with those he had seen at Mount Pelee in the Caribbean in 1902. And, he noted evidence of uplift of the island and pondered its significance.
Ever the visionary, Jaggar used his trip to renew his call for the establishment of earth observatories to study volcanoes, earthquakes, and other earth processes. He was convinced that careful and systematic study of these phenomena was critical to living safely on our planet. “Exploration, experiment, extended local observation, and permanent observatories are all needed for accumulating data concerning this old earth, which is pushing up and down its shorelines in a hundred places not yet explored, but known to geologists, and building other Bogoslofs.”
Such a network of volcano observatories exists today for much of the world. Jaggar would no doubt be pleased to see the array of modern technology used by the Alaska Volcano Observatory to issue warnings of each explosion. Satellites in earth orbit peer down at the volcano multiple times per day providing scientists a bird’s eye view of what is happening (weather permitting!) The World Wide Lightning Location Network (http://wwlln.net/) provides automated alerts – within minutes - of lightning near Bogoslof that often coincides with explosions of ash. And, infrasound or pressure waves from explosions are detected on seismic and infrasound sensors at nearby Okmok and Makushin volcanoes.
Learn more about the ongoing eruption at Bogoslof by following the Alaska Volcano Observatory at www.avo.alaska.edu.
Volcano Activity Update
Kīlauea continues to erupt at its summit and East Rift Zone. This past week, the summit lava lake level varied between about 14 and 34 m (46-112 ft) below the vent rim. The 61g flow was still active, with lava entering the ocean near Kamokuna and small surface breakouts downslope of Pu‘u ‘Ō‘ō; on the pali and the coastal plain. The 61g flows do not pose an immediate threat to nearby communities.
Mauna Loa is not erupting. During the past week, small-magnitude earthquakes continued to occur beneath the volcano. GPS measurements continue to show deformation related to inflation of a magma reservoir beneath the summit and upper Southwest Rift Zone. No significant change in the summit fumarole temperature or gas output was noted this past week.
No earthquakes were reported felt on the Island of Hawai‘i during the past week.
Visit the HVO website (http://hvo.wr.usgs.gov) for past Volcano Watch articles, Kīlauea daily eruption updates and other volcano status reports, current volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kīlauea summary update; email questions to askHVO@usgs.gov.