Gennady Karpov, deputy head of the Institute of Volcanology and Seismology under the Russian Academy of Sciences, said the Plosky Tolbachik volcano is in an ongoing eruption with consistent intensity.
The 10,100-foot volcano, one of several in a volcanic complex 210 miles from the regional capital of Petropavlovsk-Kamchatsky, first erupted on Nov. 27, its first activity in 36 years, RIA Novosti reported.
Lava flows up to 10 miles long have spewed from two fissures on the volcano's slopes, officials said.
Plosky Tolbachik has erupted 10 times since records began in 1740, including a 1975 event that was the largest in the recorded history of the Kamchatka Peninsula, they said.
That eruption dramatically changed the local landscape of the volcanic complex and was considered an ecological disaster.