Omnidirectional Modulation of Seasonal Compression of the Earth’s Crust and the Aerosol Lidar Signal in a Tunnel above the Chamber of Elbrus Volcano

From August to October 2019, the aerosol backscattering and deformation of the Earth’s crust were monitored in the tunnels of the Baksan Neutrino Observatory above the Elbrus volcano chamber. An omnidirectional modulation of the seasonal crust compression with a multiple excess of the average rate (~4 μm/day) and with a change in the sign of decrease in the lidar-signal scattering on aerosols to anomalous growth in the “hot” tunnel is found. It is established that the modulation is induced by the rapid cooling of the external atmosphere. The delays of the accelerated compression of the strainmeter arm (up to 14 μm/day) and the beginning of growth of the backscattering lidar signal relative to the beginning of the temperature decrease (~2 and ~7 days, respectively) are measured. The mechanism of the phenomena discovered is discussed.