Lidar Monitoring of Magmatic Activity in the Small Chamber of the Elbrus Volcanic Center

In this paper, the results of lidar monitoring of magmatic aerosol variation are presented. The lidar was installed in a hot dead-end tunnel at the end of the auxiliary adit of the Baksan Neutrino Observatory (BNO) of the Institute for Nuclear Research, Russian Academy of Sciences, which is located above the small magma chamber of the Elbrus Volcanic Center. A sharp (within 30 min) threefold increase in the aerosol concentration in the hot tunnel was detected (October 28, 2019, 22:30 UTC). The analysis involved data on volumetric radon activity, air temperature, and humidity. A synchronous increase in temperature, humidity, and aerosol concentration in the tunnel, as well as their correlation with the deformation of the Earth’s crust by tidal waves, which is monitored at the BNO with a laser strainmeter, was revealed. However, the threefold jump did not appear in these signals. The totality of data confirms the existence of a hot magma chamber at the base of Mount Andyrchi that was previously discovered by a small-aperture seismometer group. The assumption that the release of gases from the magma chamber could provide a jump in the concentration of aerosols without disturbing other parameters is discussed.