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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
Great Sitkin
Color Code YELLOW / Alert Level ADVISORYvolcano image
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Cleveland
Color Code ORANGE / Alert Level WATCHvolcano image
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Semisopochnoi
Color Code YELLOW / Alert Level ADVISORYvolcano image
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Veniaminof
Color Code ORANGE / Alert Level WATCHvolcano image
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NEWS
Tectonic earthquakes and Alaska volcanoes
Posted: November 30, 2018

Seismic station at Great Sitkin
Large tectonic earthquakes rarely trigger volcanic eruptions; this is an active area of research, but there are only a few convincing cases globally, and those are most likely to occur at volcanoes already in eruption or primed to erupt.
• The current eruptive activity at Veniaminof, and the unrest at Cleveland, Semisopochnoi, and Great Sitkin, continues without change since this morning's large tectonic earthquake.
• AVO maintains ground-based networks for seismic and GPS monitoring of Alaska volcanoes, along with remote sensing methods such as satellite and infrasound.
• AVO’s volcano-monitoring networks also record tectonic earthquakes, and broaden the data set of all types of earthquakes, such as the tectonic earthquake experienced on the morning of 30 November 2018.
The M7.0 earthquake was tectonic and not volcanic:
• For more information about this tectonic earthquake, please visit the National Earthquake Information Center: https://earthquake.usgs.gov/earthquakes/eventpage/us1000hyfh/oaf/commentary and https://earthquake.usgs.gov/earthquakes/eventpage/us1000hyfh/executive or the Alaska Earthquake Center: https://earthquake.alaska.edu/anchorage-m70-what-we-know-so-far.
• The earthquake occurred at a depth of 24 miles beneath the surface (40 km).
• The earthquake occurred in the subduction zone - the interface between the Pacific and North America plates, which extends to depths of 24 to 37 miles (40 to 60 km).
• Subduction zones, where most active volcanoes are found, can generate high rates of earthquakes that are not volcanic.
• Aftershocks will occur.
• The Aleutian arc is a seismically active region, evidenced by the many moderate to large earthquakes occurring each year. Since 1900, this region has hosted twelve large earthquakes (M>7.5) including the May 7, 1986 M8.0 Andreanof Islands, The June 10, 1996 M7.9 Andreanof Islands, and the November 17, 2003 M7.8 Rat Islands earthquakes.
• The most recent large earthquake to occur in this area was the 2016 M7.1 Iniskin earthquake.

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LAST ACTIVITY REPORT
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ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, December 13, 2018, 11:30 AM AKST (Thursday, December 13, 2018, 20:30 UTC)


SEMISOPOCHNOI VOLCANO (VNUM #311060)
51°55'44" N 179°35'52" E, Summit Elevation 2625 ft (800 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Unrest continues at Semisopochnoi volcano. No eruptive activity was detected over the past day in regional infrasound data or cloudy satellite views of the volcano. Local seismic data remains offline.

Semisopochnoi is monitored with an on-island seismic network, though this is currently off-line, and remotely by satellite and lightning sensors. Furthermore, an infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a 13 minute delay if atmospheric conditions permit.


VENIAMINOF VOLCANO (VNUM #312070)
56°11'52" N 159°23'35" W, Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Webcam and satellite imagery collected over the past several days suggests that effusion of lava from Veniaminof's intracaldera cone has stopped. However, the local seismic network continues to record low-frequency seismic events and weak tremor bursts, so it is possible that weak eruptive activity may still be happening.

Veniaminof volcano is monitored with a local real-time seismic network, which will typically allow AVO to detect changes in unrest that may lead to a more significant explosive eruption. AVO combines seismic, infrasound, lightning, and satellite data for rapid detection of such events.



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

Low-level unrest continues at Cleveland volcano. No significant activity has been detected in seismic or regional infrasound data since yesterday's small explosion. No activity was observed in partly cloudy to cloudy satellite views.

Cleveland volcano is monitored by only two seismic stations, which restricts 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. The web camera, one seismic station, and the local infrasound array are offline due to a equipment failure on September 23rd. This hampers efforts to rapidly detect explosive activity; however, Cleveland remains monitored with a single seismic station and regional instruments.


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

Low-level unrest continues at Great Sitkin volcano. Numerous small earthquakes associated with the ongoing unrest continue to be recorded on the local seismic network. No eruptive activity was observed in partly cloudy to cloudy satellite views of the volcano over the past day. No explosive activity was detected on a regional infrasound array on Adak Island.

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.


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

SUBSCRIBE TO VOLCANO ALERT MESSAGES by email: http://volcanoes.usgs.gov/vns/

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CONTACT INFORMATION:

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

Pavel Izbekov, Acting Coordinating Scientist, UAFGI
peizbekov@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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RUSSIAN VOLCANO INFORMATION

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Page modified: March 19, 2018 16:09
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