July 9 (UPI) -- An Alaskan volcano has erupted again, prompting an aviation warning by the Alaska Volcano Observatory.
On Saturday, the Bogoslof volcano spewed an ash cloud 30,000 above the ground over the Aleutians Islands, the observatory said in a notice. The first eruption began at 10:15 a.m. and lasted about 9 minutes. It was followed by a shorter pulse 5 minutes later.
On Sunday, the observatory lowered the warning level from "red" -- the highest -- to "orange" because no further ash emissions occurred and seismic activity remains low.
"Additional ash-producing eruptions could occur at any time, however, with no detectable precursors," the observatory said.
The observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute and the Alaska Division of Geological and Geophysical Surveys.
The current series of eruptions began in December, according to the observatory.
Because the volcano is under the flight path of planes flying from Asia to North America, its ash cloud could affect passing aircraft.
"Ash and aircraft do not mix, as volcanic ash is abrasive, melts at jet engine temperatures, and can cause engine failure," the United States Geological Survey said in a release in March.
In May, the volcano's eruption prompted a similar temporary aviation alert but it subsequently downgraded to "orange" from "red" and the warning, like this weekend, was lifted.
In 2010, Eyjafjallajokull volcano's eruption in Iceland caused the cancellation of flights around Europe for six days.