One of Alaska's most restless volcanoes has shot an ash cloud 15,000 feet into the air in an eruption that is visible for miles.
An air traffic controller in the region said small planes have flown around the plumes from Pavlof Volcano. Ash would have to rise tens of thousands of feet to threaten larger planes.
The eruption began on Monday, and photographs show lava spraying out from the summit of the volcano, located 625 miles from Anchorage.
The Alaska Volcano Observatory said clouds of ash, steam and gas have occasionally reached the 20,000-foot level and have been visible from the nearby communities of Cold Bay and Sand Point.
Onsite seismic instruments have detected an increase in the force of tremors from the 8,262-foot volcano.
Typically, Pavlof eruptions are gas-rich fountains of lava that can shoot up to a few thousand feet. But its ash clouds are usually less dense than the plumes of more explosive volcanoes that pose a greater hazard to aircraft, scientists say.
Pavlof is among the most active volcanoes in the Aleutian arc, with nearly 40 known eruptions, according to the observatory.
The volcano last erupted in 2007. During the 29-day eruption, Pavlof emitted mud flows and erupting lava, as well as ash clouds up to 18,000 feet.
In early May, Cleveland Volcano, on an uninhabited island in the Aleutian Islands, experienced a low-level eruption. Satellite imagery shows the volcano has continued to discharge steam, gas and heat in the past week. New analysis of earlier images showed a small lava flow going over the south east rim of the summit crater, the observatory said.
The volcano is a 5,675-foot peak on a remote island 940 miles from Anchorage. Cleveland's most recent significant eruption began in February 2001 and sent ash clouds up to 39,000 feet above sea level. It also produced a rocky lava flow and hot debris that reached the sea.