Tuesday, 29 March 2016

Eruption on Mount Pavlof causes severe disruption to flights over Alaska.

Mount Pavlof, a 2.5 km high stratovolcano (cone-shaped volcano made up of layers of ash and lava) on the Alskan Peninsula, underwent a significant eruption slightly before 4 pm local time on Sunday 27 March 2016, producing an ash column 11.3 km high that drifted 650 km to the northeast. There are no reports of any ashfalls affecting local communities (which are mostly to the southwest of the volcano), however the ash cloud has cut across flight paths over Alaska, causing severe disruption to flights, as planes cannot safely approach such clouds. People in the area have also reported seeing lava fountains on the volcano. This is the first major eruption on Pavlof since November 2014.

Ash column over Mount Pavlof at about 7.00 pm on 27 March 2016. Colt Snapp/Twitter.

Pavlof is located between Cold Bay and Pavlof Bay near the tip of the Alaskan Peninsula. It has several active vents on its north and east flanks, it's remoteness and inaccessibility meaning that it is usually hard to tell from exactly which of these an individual eruption is occurring. Pavlof is considered to be one of America's most active volcanoes, and though it is located in a remote spot with no settlement close by, it still presents a serious threat to air-traffic.

 The approximate location of Mount Pavlof. Google Maps.

Volcanic ash is extremely hazardous to aircraft in a number of ways. At its most obvious it is opaque, both visually and to radar. Then it is abrasive, ash particles physically scour aircraft, damaging components and frosting windows. However the ash is most dangerous when it is sucked into jet engines, here the high temperatures can melt the tiny silica particles, forming volcanic glass which then clogs engine. When this happens the only hope the aircraft has is to dive sharply, in the hope that cold air passing through the engine during the descent will cause the glass to shatter, allowing the engine to be restarted. Obviously this is a procedure that pilots try to avoid having to perform.

The volcanoes of the Alaskan Peninsula and Aleutian Islands are fed by magma rising from the Pacific Plate, which is being subducted beneath the North American Plate to the south along the Aleutian Trench. As the subducting plate sinks into the Earth it is subjected to enormous heat and pressure, causing more volatile minerals to melt. These then rise through the overlying North American plate as magma, fueling the Alaskan volcanoes.

How the subduction of the Pacific Plate beneath the North American Plate fuels the volcanoes of Alsaska. Alaska Volcano Observatory.

See also...

http://sciencythoughts.blogspot.co.uk/2014/06/eruptions-on-mount-pavlof-on-alaskan.htmlEruptions on Mount Pavlof, on the Alaskan Peninsula.                                                  Mount Pavlof, a 2.5 km high stratovolcano began erupting on Saturday 31 May 2014, for the first time since the preceding September, according to the Alaska Volcano Observatory. This...
http://sciencythoughts.blogspot.co.uk/2013/09/magnitude-70-earthquake-in-aleutian.htmlMagnitude 7.0 Earthquake in the Aleutian Islands.                                                         The United States Geological Survey recorded a Magnitude 7.0 Earthquake at a depth of 33.5 km to the south of the Andreanof...
http://sciencythoughts.blogspot.co.uk/2013/08/eruption-on-mount-veniaminof.htmlEruption on Mount Veniaminof. Mount Veniaminof, an Alaskan volcano which has been experiencing low level activity since June, erupted suddenly on Friday 30 August, sending a column of ash 4.8 km into the air, according to the Alaska Volcano Observatory. There is no direct danger to anybody...
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