Physical Effects in the Atmosphere and Geospace Accompanying the Surface Explosion in the City of Beirut on August 4, 2020: Observational Data

On August 4, 2020, a massive explosion rocked the city of Beirut, Lebanon. The explosion yield has been estimated to be equivalent to 1 kt of TNT, and the physical effects of the explosion on the Earth–atmosphere–ionosphere–magnetosphere system have been analyzed in detail. The possible effects of powerful explosions are of considerable interest to geophysicists and radio physicists to analyze. These effects make it possible to reveal the mechanisms for transporting the disturbances in both the vertical and horizontal directions as well as the mechanisms for interaction of the subsystems in the Earth–atmosphere–ionosphere–magnetosphere system. The purpose of the present paper is to describe radio and magnetometer observations of the processes that accompanied the powerful explosion in Beirut on August 4, 2020, in the lower ionosphere and in the geomagnetic field. The observations of the possible response of the near-Earth medium to the explosion have been made with a fluxmeter magnetometer and a radio system for sounding the ionosphere at oblique incidence. The latter system detected an increase of up to 5.3° in the phase of the ionospheric wave and an increase of 3.3% in the signal amplitude caused by an electron density change of approximately 3%. If these increases are due to the explosion, the speed of propagation of the disturbance is estimated to be approximately 3 km/s. The fluxmeter magnetometer has detected changes in the character of variations in the level of the geomagnetic field occurring 5 min and 79 min after the explosion. If these variations were associated with the explosion, the speeds of propagation can be estimated to be tens of km/s and greater as well as 490 m/s. The MHD waves have a greater speed, and the acoustic gravity waves have a smaller speed, respectively.