MOSCOW, June 17 (UPI) -- The Kizimen and Karymsky volcanoes on Russia's Kamchatka Peninsula spewed ash and gas, accompanied by earth tremors, a Russian science agency said Friday.
A spokesman for the Geophysical Service of the Russian Academy of Sciences said as many as 400 tremors have been registered, ITAR-Tass reported Friday.
The "orange" aviation alert code was activated, warning of the danger volcanic dust and emitted gases can pose to aircraft, officials said.
Rising to an altitude of 7,795 feet, the Kizimen volcano is about 265 kilometers from Petropavlovsk-Kamchatsky. Geologists estimate the volcano formed about 12,000 years ago.
One of 29 active volcanoes on the Kamchatka peninsula, Kizimen was violent in 1928 and 1929. It began to exhibit activity again in 2009.
The 4,875-foot Karymsky is the most active volcano of Kamchatka's eastern volcanic zone and a symmetrical stratovolcano, the academy spokesman said. Its activity increased dramatically in 1996 and still erupts periodically.