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The Alaska Volcano Observatory (AVO) is a joint program of the United States Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS).
RESTLESS VOLCANOES
Cleveland
Color Code ORANGE / Alert Level WATCHvolcano image
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Shishaldin
Color Code YELLOW / Alert Level ADVISORYvolcano image
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New publication: Geologic map of Chiginagak volcano
Posted: January 05, 2018

Chignagak volcano. Photo by Willie Scott, August 24, 2008.

A newly published geologic map, map report, and its associated GIS files is available for download here. Chiginagak volcano is a small volcanic center on the Alaska Peninsula, with historical observations of fumarolic activity, and a 2005 noneruptive summit heating event and subsequent ice melt, lahar, acid flood, and sulfuric-acid-aerosol release.
New publication: Major-element glass compositions of tephra from the circa 3.6 ka eruption of Aniakchak volcano, Alaska Peninsula, Alaska
Posted: January 05, 2018

Aniakchak Caldera, photo by Tim Plucinski
Major-element glass compositions of tephra from the circa 3.6 ka eruption of Aniakchak volcano, Alaska Peninsula, Alaska publication is now available for download, here.
ABSTRACT:
This Raw Data File presents major-oxide glass geochemical results from the ca. 3.6 ka caldera-forming eruption of Aniakchak volcano, Alaska. These data are part of a larger effort to identify and characterize tephra deposits from the largest eruptions in Alaska for use as geochronological marker horizons. Aniakchak is one of at least 29 volcanoes in Alaska that has had multiple large tephra-producing eruptions. Other deposit and sample metadata including geospatial distributions of this tephra deposit are held in the Alaska Volcano Observatory’s online database, the Geologic Database of Information on Volcanoes in Alaska (GeoDIVA), and will be linked to these new geochemical data once published. Products included in this data release are background information on the larger project, methods of sample collection, processing, analysis, and data reduction spreadsheets showing 1)raw point major-oxide data, 2)normalized and averaged major-oxide data, and 3)basic sample metadata.
New publication: The 2014 eruptions of Pavlof Volcano, Alaska
Posted: January 05, 2018

Pavlof, Nov 2014. Photo by Doug Damberg
The 2014 eruptions of Pavlof Volcano, Alaska publication is available for download here. This publication details the chronology and eruptive products of Pavlof's May 2014 and November 2014 eruptions.
New publication: Historically active volcanoes of Alaska reference deck, v.2
Posted: January 05, 2018

Volcano reference deck
This publication is a little unusual, as it is in the form of playing cards. Each full-color card provides the location and photo of a historically active volcano and up to four icons describing its historical activity. The icons represent characteristics of the volcano, such as a documented eruption, fumaroles, deformation, or earthquake swarms; a legend card is provided. See DGGS website here for more information and how to order.

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ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, January 19, 2018, 2:47 PM AKST (Friday, January 19, 2018, 23:47 UTC)


CLEVELAND VOLCANO (VNUM #311240)
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Recent satellite data indicate a new lava flow within the summit crater that has been emplaced since the last observations of elevated surface temperatures at Cleveland on January 5. No other activity was seen this week in satellite views, including several during clear conditions. Nothing significant was observed in seismic or infrasound data as well. The last small explosion at Cleveland occurred on December 17, which may have cleared the vent making way for the recently observed lava flow to effuse into the summit crater.

Cleveland volcano is monitored with a limited real-time seismic network, which inhibits AVO's ability to detect precursory unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data.


Cleveland volcano forms the western portion of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. The volcano is located about 75 km (45 mi) west of the community of Nikolski, and 1500 km (940 mi) southwest of Anchorage. The most recent significant period of eruption began in February, 2001 and produced 3 explosive events that generated ash clouds as high as 39,000 ft above sea level. The 2001 eruption also produced a lava flow and hot avalanche that reached the sea. Since then, Cleveland has been intermittently active producing small lava flows, often followed by explosions that generate small ash clouds generally below 20,000 ft above sea level. These explosions also launch debris onto the slopes of the cone producing hot pyroclastic avalanches and lahars that sometimes reach the coastline.

SHISHALDIN VOLCANO (VNUM #311360)
54°45'19" N 163°58'16" W, Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Elevated seismicity and infrasound resulting from robust shallow degassing in the conduit at Shishaldin persisted over the past week. A steam plume from the summit was noted in satellite data on Wednesday. No other volcanic activity was observed in satellite images, even with some clear viewing conditions during the week. Web camera views have been obscured by snow since January 8.

Shishaldin is monitored by local seismic and infrasound sensors, satellite data, a web camera, a telemetered geodetic network, and distant infrasound networks.


Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft above sea level.

GREAT SITKIN VOLCANO (VNUM #311120)
52°4'35" N 176°6'39" W, Summit Elevation 5709 ft (1740 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

The Color Code/Alert Level for Great Sitkin was lowered to GREEN/NORMAL yesterday based on decreasing earthquake activity over the past 2 months. In addition, no significant activity had been observed in satellite data and no steam plumes had been reported over the same 2 month time period.

The decline over the past 2 months in the number of earthquakes suggests an intrusion of magma beneath Great Sitkin, which caused elevated seismicity during late 2016 and most of 2017, has possibly stalled and the volcano is returning to a period of background seismicity. Future intrusions at Great Sitkin, or a remobilization of the most recent intrusion, should lead to an increase in earthquakes prior to any eruptive activity. A significant number of small earthquakes began occurring again late on January 18, and AVO continues to monitor this activity closely.

Great Sitkin volcano is monitored with a local real-time seismic network, which will typically allow AVO to detect changes in unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption would be accomplished using a combination of seismic, infrasound, lightning, and satellite data.


Great Sitkin Volcano is a basaltic andesite volcano that occupies most of the northern half of Great Sitkin Island, a member of the Andreanof Islands group in the central Aleutian Islands. It is located 43 km (26 miles) east of the community of Adak. The volcano is a composite structure consisting of an older decapitated volcano and a younger parasitic cone with a 2-3 km diameter summit crater. A steep-sided lava dome, emplaced during an eruption in 1974, occupies the center of the crater. Great Sitkin erupted at least three times in the 20th century, most recently in 1974. That eruption produced a lava dome and at least one ash cloud that likely exceeded an altitude of 25,000 ft above sea level. A poorly documented eruption occurred in 1945, also producing a lava dome that was partially destroyed in the 1974 eruption. Within the past 280 years a large explosive eruption produced pyroclastic flows that partially filled the Glacier Creek valley on the southwest flank.

OTHER ALASKA VOLCANOES

Information on all Alaska volcanoes is available at : http://www.avo.alaska.edu.

For definitions of Aviation Color Codes and Volcano Alert Levels, see: http://www.avo.alaska.edu/color_codes.php

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CONTACT INFORMATION:

Michelle Coombs, Scientist-in-Charge, USGS
mcoombs@usgs.gov (907) 786-7497

Jeff Freymueller, Coordinating Scientist, UAFGI
jfreymueller@alaska.edu (907) 322-4085

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.
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Page modified: November 29, 2017 12:41
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