Alaska Volcano that has been erupting since last month continuously build up a lava leak on the flanks of the volcano and increases the possibility of an explosive eruption.
The Alaska Volcano Observatory raised the volcano�s alert level to watch status on Tuesday.
The dome, if it continues to grow, could plug up the crater, creating pressure that could result in "a fairly sizable explosion that could throw ash up to flight levels," according to John Power, scientist in charge at the Alaska Volcano Observatory.
"An eruption for us is any time that magma is coming up from the surface in the ground," Power further said. "This is very much happening here."
Cleveland Volcano, a 5,676-foot peak located on Chuginadak Island, about 940 miles southwest of Anchorage, has been in low-level eruption since the end of July.
Chuginadak Island is uninhabited and the volcano has not posed an immediate hazard to anyone or affected air traffic, even though it lies directly in the North America-to-Asia flight corridor used by major airlines, Power said.
Cleveland Volcano covers about half of Chuginadak Island. The closest community to the volcano is Nikolski, an Aleut village of about 20 people located 45 miles to the east.
The fishing port of Unalaska/Dutch Harbor is about 150 miles to the east of the volcano.
Cleveland's last major eruption was in 2001, but it has had several smaller or suspected ash-spewing eruptions since then.