The Alaska Volcano Observatory has issued a yellow warning, which USGS indicates means: “Volcano is exhibiting signs of elevated unrest above known background activity.” High-resolution satellite images yesterday showed a small ash deposit coming from the North Cerebus Crater on the Semisopochnoi Island in Alaska
The steam has obscured views into the crater.
The Alaska Volcano Observatory said: “There is no evidence for continuing activity, but observation of a new deposit suggests renewed unrest.”
They added how they are “increasing the Aviation Color Code to yellow and the Volcano Alert Level to advisory”.
The Observatory continued: “Small eruptions producing minor ash deposits within the vicinity of the volcano are typical of activity during unrest at Semisopochnoi since September 2018, with the last detected activity in June 2020.
“Local seismic stations have been offline since November 11, 2020.
“New explosions could occur at anytime with no warning.”
The volcano is monitored remotely by satellite and lightning senors.
The Observatory added in their report: “An infrasound array on Adak Island could detect explosive emissions from Semisopochnoi with a 13 minute delay if atmospheric conditions permit.”
A historic eruption was reported in 1873, and at least four others may have occurred in the previous hundred years, but documentation is scant.
In December, geologists discovered that a trail of volcanic islands off the coast of the US state may actually be connected to one giant caldera.
The cluster of six volcanoes in the Aleutian Islands – known as the Islands of the Four Mountains – may be connected to a much bigger underwater volcano.
Scientists analysed seismic activity, gas emissions, gravity measurements and geochemistry in the region surrounding the six stratovolcanoes of Carlisle, Cleveland, Herbert, Kagamil, Tana and Uliag – and their results suggested activity could be traced to a bigger source.
Alaska is home to more than 40 active volcanoes and many more potentially active volcanoes.
Many of these occur along the Alaska Peninsula and Aleutian Island.
In 2016, the Pavlof volcano on the Peninsula sent ash 20,000 feet into the air.
The US state is also known for having frequent earthquakes and in December recorded more than 3,500 quakes through the month.