The eruption of an Alaskan volcano that's been pouring out lava and ash for several years has intensified and scientists have reacted by issuing the highest alert in five years, authorities say.

The scientists at the Alaska Volcano Observatory put out a red alert, the state's first since 2009, after the Pavlof Volcano spewed ash into the atmosphere as high as 24,000.

The eruption of the volcano in an uninhabited area of the Alaskan Peninsula has not caused any disruption of air traffic in the region, as favorable weather conditions have made it possible for airliners to avoid the area without encountering delays, officials said.

Although the volcano is located beneath a route aircraft flying between North America and Asia frequently use, most flights have reached altitudes of 30,000 feet and above in the region and can safely navigated around the volcano's ash clouds, they said.

The increase in the eruption's intensity began Monday with an upturn in seismic activity, prompting the red alert under the Current Aviation Color Code warning system, observatory scientists said.

"It can erupt for weeks or months," observatory research geologist Michelle Coombs said.

"I don't think we will be at red for that long, but we are expecting it to go for a while based on its past."

The ash plumes are the result of lava spewed from the summit crater of the 8,261-foot volcano falling onto glacier ice, she said.

Pavlof Volcano has been one of the most active volcanoes in the United States, with at least eight eruptions since 1980.

A period of dormancy from 1996 to August of 2007 was the longest such period since Pavlof's eruptions started being recorded.

In 2013 an eruption lasted from May to August.

Located in the Aleutian Range of mountains, Pavlof's eruption is affecting areas that are unpopulated except for a few hunting destinations, Coombs said, so there is currently no danger to humans.

"Right now, with the weather clear, it's just putting on a good show," she said. "We're getting a lot of pilot reports and a lot of good photos, so we're able to keep a good eye on it."

The last red alert in Alaska occurred in 2009 when ash plumes from Mount Redoubt rose to more than 50,000 feet into the air.