Infrasonic waves from volcanic eruptions on the Kamchatka peninsula

Abstract

The IS44 station operates at the observation point of Nachiki on the Kamchatka peninsula, which is part of the International Monitoring System (IMS), and it helps verify compliance with the Comprehensive Nuclear Test-Ban Treaty (CTBT). The Kamchatka Branch, Geophysical Service, Russian Academy of Sciences (KB GS RAS), has a station operating in the village of Paratunka. Both of these stations allow one to monitor strong explosive eruptions of andesitic volcanoes.1 Both kinematic and dynamic parameters of acoustic signals accompanying the eruptions of the Bezymyannyi volcano (at a distance of 361 km from Nachiki) in 2009–2010 and the Kizimen volcano (at a distance of 275 km) on December 31, 2011, are considered. A low-frequency rarefaction phase 60 s in length has been revealed in the initial portion of the record of acoustic signals accompanying such strong eruptions. It is shown that the rarefaction phase occurs due to the rapid condensation of superheated juvenile vapor2 that enters the atmosphere during such explosions.3 The amount of volcanic ash emitted into the atmosphere has been estimated within (3.2–7.3) 106 m3 on the basis of acoustic signals recorded during the eruptions under consideration.