Tuesday 3 June 2014

Eruptions 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 was initially detected as a sharp rise in temperature in thermal satellite images, and was later confirmed by observations from a pilot who reported an ash plume rising 2.0-2.5 km above the summit of the volcano and drifting to the north. Incandescent glowing was seen in the crater of Pavlof overnight between Saturday 31 May and Sunday 1 June, and a 3.5 km ash plume seen over the volcano in the morning, which drifted about 40 km on the wind. A small lava flow was spotted on the north flank of the volcano, along with what appeared to be several small lahars (floods of ash-laden water). On Monday 2  June an ash column was observed rising 6.7 km above the summit and drifting about 80 km to the east, and considerable seismic (Earthquake) activity was recorded around the volcano.

Eruption on Mount Pavlof, Alaska, on 2 June 2014. Christopher Diaz/northernXposed Photography/Alaska Volcano Observatory.

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...

The United States Geological Survey recorded a Magnitude 7.0...

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...

Mount Pavlof, an active volcano on the Alaska Peninsula, which has been erupting intermittently since mid-May 2013, underwent a sharp...

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