SAN FRANCISCO, July 9 (Xinhua) -- Bogoslof volcano in Alaska, the largest and most sparsely populated U.S. state, appeared to be less active Sunday, after an eruption a day earlier, leading authorities to lower the alert for airplanes flying over the area.
The Alaska Volcano Observatory (AVO) said in an updated posting on the website that "no activity has been detected seismic, infrasound, or cloudy satellite data in the past 24 hours," and it "lowered the Aviation Color Code/Volcano Alert Level to ORANGE/WATCH this morning."
Located at the southern edge of the Bering Sea, 35 miles, or 56 kilometers, northwest of Unalaska Island of the Aleutian Island chain, Bogoslof volcano rises about 6,000 feet, or 1,800 meters, from the seabed. It erupted Saturday, shooting an ash cloud up to 30,000 feet, or 9,000 meters.
As the area uninhabited by people sits under the path of flights from Asia to North America, AVO initially warned airplanes to avoid the volcano, which has erupted several times since December last year.
AVO, a cooperative program of the U.S. Geological Survey (USGS), the University of Alaska Fairbanks Geophysical Institute, the Alaska Division of Geological and Geophysical Surveys, said a Temporary Flight Restriction (TFR) is in effect over the volcano at the present time.
"Bogoslof volcano remains at a heightened state of unrest and in an unpredictable condition," noted the observatory. "Activity can escalate quickly with additional explosions producing high-altitude (more than 15,000 feet, or 4,500 meters) volcanic clouds with little to no detectable precursory activity."