(CNN)Lava and ash spewing from the ongoing eruption of the Shishaldin volcano in Alaska triggered an aviation warning Sunday.
The volcano's aviation alert level was raised to red, or warning level, Sunday morning when data from the Alaska volcano observatory showed that eruptive activity had intensified, according to the United States Geological Survey. Eruptive activity includes elevated seismic actions, lava flows and plumes of steam and ash.
Mt. Shishaldin is located near the center of Unimak Island in the Aleutian Islands about 680 miles southeast of Anchorage. It is the highest peak on the Aleutian Islands, according to the observatory.
The volcano began erupting in July, the observatory website said.
Sunday's eruptive activity created lava flows on the northeast and north flanks of the volcano as well as a steam and ash plume that extended 90 miles east southeast at a height of 20,000 feet. By Sunday afternoon the plume had grown to 30,000 feet before ash production stopped around 10 p.m. local time, the report said.
The aviation alert was lowered to orange, or watch level, early Monday morning once the ash production stopped and the plume dissipated.
At least three other Alaskan volcanos remained under a yellow or advisory level, the report said.