Ongoing Eruption of Alaskan Volcanoes Poses Concern to Air Traffic

A plume of volcanic ash and gas continues to billow from Mt. Pavlof in Alaska; the volcano's ongoing eruption places air traffic in the region at risk of significant obstacles if the ash cloud rises any higher that its current altitude of 20,000 feet above sea level.

Mt. Pavlof is one of two volcanoes along Alaska's Aleutian Island chain that have seen activity recently, prompting the Alaskan Volcano Observatory (AVO) to place aviation warnings at code orange, the second highest level. Lava fountaining from the summit of Pavlof has been observed and the plume of volcanic ash can be observed extending as far as 160 miles (100 km) from the summit.

The AVO reports "nearly continuous" elevated seismic activity around Mt. Pavlof.

Cleveland Volcano has been erupting for nearly three weeks and was placed on a code Orange alert earlier this month after gas and volcanic ash began billowing from the summit. A report Tuesday a 32-foot-wide (100 meter) lava flow extending about a mile (1.5 kilometers) down the mountain's southern flank was the first report of lava from Cleveland since the volcano began erupting May 4.

Observations of volcanic activity at Cleveland Volcano, the more remote of the two erupting volcanoes, were obscured by heavy cloud cover, the AVO said in its latest report.

The eruption at Pavlof Volcano, the taller of the two mountains, was confirmed Tuesday following an increase in seismic activity and presence of intense elevated surface temperatures. Reports from pilots and satellite imagery revealed a flow of lava from Pavlof running down the mountain's north face for about a third of a mile (500 meters).

Cleveland (5,675 feet; 1,730 meters) and Pavlof (8,251 feet; 2,515 meters) are nearly symmetrical stratovolcanoes about 400 miles (645 km) apart.

Both are considered among the most active volcanoes in the region, Cleveland having erupted at least 22 times in the last 230 years and Pavlof having erupted a dozen times since 1980.

Cleveland is very far west along the island chain and there are no ground instruments monitoring the isolated volcano, meaning it takes longer to realize an eruption is occurring there. Pavlof is closer to mainland Alaska and is monitored by ground equipment.

While the volcanoes' remote location poses little risk to people on the ground, the erupting mountains can potentially have serious consequences for the high-volume air traffic over the region.

CNN reported that 90 percent of air freight from Asia to Europe and North America flies over Alaska airspace, and hundreds of flights fly through Anchorage's air space daily.

"We think of the Aleutian Islands as being remote and desolate" John Power, a scientist from the U.S. Geological Survey, told CNN, "but when you come up to 30,000 feet we are talking about 20 to 30,000 people there every single day."