Shishaldin on orange alert

Image Wikimedia Commons

Shishaldn is on alert level orange ( April 16th 2014) and has been since January., which means it is on watch. Some puffs of smoke have been detected and there was a heat signature back in march. So i thought it worth a post so our readers can keep in eye on this beautiful volcano. There seems to be no imminent risk for people because of the remote location of the volcano. Just pilots should watch if there were recent ash emissions. The volcano is one of the more active volcanoes of the Aleutan chain. The following is mostly a quote from Wikipedia:

“It is the highest mountain peak of the Aleutian Islands. The most symmetrical cone-shaped glacier-clad large mountain on earth, the volcano’s topographic contour lines are nearly perfect circles above 6,500 feet (2,000 m). The lower north and south slopes are somewhat steeper than the lower eastern and western slopes. The volcano is the westernmost of three large stratovolcanoes along an east–west line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning “mountain which points the way when I am lost.” The upper 2,000 meters is almost entirely covered by glacial snow and ice. In all, Shishaldin’s glacial shield covers about 35 square miles (91 km2). It is flanked to the northwest by 24 monogenetic parasitic cones, an area blanketed by massive a lava flows. The Shishaldin cone is less than 10,000 years old and is constructed on a glacially eroded remnant of an ancestral soma and shield. Remnants of the older ancestral volcano are exposed on the west and northeast sides at 1,500–1,800 meters elevation. The Shishaldin edifice contains about 300 cubic kilometers of material. A very steady steam plume rises from its small summit crater which is about 500 feet (150 m) across and slightly breached along the north rim.”

http://www.avo.alaska.edu/images/image.php?id=57861

Image from http://www.avo.alaska.edu/images/image.php?id=58171

http://www.alaskapublic.org/wp-content/uploads/2014/01/Shishaldin.jpg Shishaldin Volcano with a typical steam plume, pictured on Sept. 14, 2013. Photo by Joseph Korpiewski, U.S. Coast Guard.

Description available on the AVO page : ”
From Miller and others (1998): “Shishaldin Volcano, located near the center of Unimak Island, is a spectacular symmetrical cone about 16 km in diameter at the base. The mountain, which rises to a summit 2857 m above sea level, is the highest peak in the Aleutian Islands and has a small summit crater from which a steady cloud of steam is emitted. The upper 2000 m is almost entirely covered by perennial snow and ice. It is flanked to the northwest by 24 monogenetic parasitic cones (Fournelle, 1988). The Shishaldin cone is less than 10,000 year old and is constructed on a glacially eroded remnant of an ancestral soma and shield (Fournelle, 1988), which in turn are underlain by volcaniclastic rocks of probable late Tertiary age (McLean and others, 1978). Fournelle (1988) suggests that the basement may consist, at least in part, of plutonic rocks.”

http://www.avo.alaska.edu/images/image.php?id=10005

Alaska Observatory on Shishaldin http://www.avo.alaska.edu/activity/Shishaldin.php

A webcam is pointed at it, though the weather is really bad rather often. http://www.avo.alaska.edu/webcam/Shishaldin.php

A clear day image of this cam:

http://www.avo.alaska.edu/webcam/Shishaldin.php#

and a video of the last 24 hours is also available. http://www.avo.alaska.edu/webcam/Shishaldin.php#
Two webicorders show Shishaldins activity: http://www.avo.alaska.edu/webicorders/Shishaldin/SSLW_EHZ_AV.php but the second one seems to be out of order http://www.avo.alaska.edu/webicorders/Shishaldin/SSBA_BHX_AV.php

Links:

GVP on Shishaldin http://www.volcano.si.edu/volcano.cfm?vn=311360

Volcanodiscovery on Shishaldin http://www.volcanodiscovery.com/shishaldin.html
“The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning “mountain which points the way when I am lost.” A steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, Shishaldin is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 m elevation. Shishaldin contains over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century.”

Volcano World: http://volcano.oregonstate.edu/shishaldin

Wikipedia : http://en.wikipedia.org/wiki/Mount_Shishaldin

Image Wikimedia Commons

Volcano Live http://www.volcanolive.com/shishaldin.html ( John Seach)

Really nice summary also available on http://shishaldinvolcano.blogspot.co.at

Photovolcanica: http://www.photovolcanica.com/VolcanoInfo/Shishaldin/Shishaldin.html

Geology links:

Arc Volcanism in a nutshell: http://geology.about.com/library/bl/blnutshell_subducfactory.htm

Geology and petrology of ejecta from the 1999 eruption of Shishaldin Volcano, Alaska, Stelling, P.; Beget, J.; Nye, C.; Gardner, J.; Devine, J. D.; George, R. M. M. : http://adsabs.harvard.edu/abs/2002BVol…64..548S

Hazrd Assesment : http://137.229.113.30/webpubs/dggs/ri/text/ri2002_004.pdf ( Preliminary volcano-hazard assessment for Shishaldin Volcano, Alaska )

Acoustic signals of the eruption 1999 http://www.giseis.alaska.edu/Input/jackie/shishaldin.html

 

Unimak Volcanoes: http://unimak.us/landforms.shtml

http://unimak.us/landforms.shtml

Earth from Orbit also has a nice image of the volcanoes of the Unimak Islands

Image taken from the ISS found on Twitter

Spica

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