The Alaska Volcano Observatory has lowered the alert level for a volcano on an uninhabited Aleutian Island.

The observatory says satellite views of 5,675-foot Cleveland Mountain about 940 miles southwest of Anchorage show no evidence of eruptions since an explosion Aug. 20.

A satellite last detected fresh lava in the summit in early May.

The observatory says sudden explosions of blocks and ash clouds that could threaten aircraft remain possible with little warning.

The observatory lowered the Aviation Color Code from orange to yellow.

Orange means a volcano is exhibiting heightened or escalating unrest or that an eruption is under way with minor ash emissions. Yellow means unrest is elevated but decreasing.