Physical Effects in the Atmosphere and Geospace due to Ground-Based Events as Exemplified by the Explosion in the City of Beirut on August 4, 2020. Theoretical Modeling Results

Abstract

The study of direct and reverse, positive and negative interconnections among the subsystems in the Earth (internal spheres)–atmosphere–ionosphere–magnetosphere (EAIM) system is commonly based on high-power active experiments. One of the possible experiments is an impact of large chemical explosions in EAIM system. Examples include active experiments utilizing 5 kt TNT, 1.5 kt TNT, and 2 kt TNT yield explosions. A powerful chemical explosion has been shown earlier to affect all geospheres, viz., it generates seismic waves in the lithosphere, disturbances in the electric field, electromagnetic emissions, acoustic and atmospheric gravity waves (AGWs), traveling ionospheric disturbances, and MHD waves in the near-Earth plasma. The physical effects and ecological consequences of multiple chemical explosions and accompanying fires have also been studied earlier. The main conclusion that has been drawn in these studies is that a response to such an impact can appear in all EAIM system subsystems. This paper aims to describe the principle physical effects in the atmosphere and geospace accompanying the powerful explosion in the city of Beirut on August 4, 2020. A comprehensive analysis of the main physical processes accompanying the explosion has been performed to determine the following. The Beirut explosion yield is estimated to be approximately 1 kt TNT. More than 90% of the explosion energy was transformed into the energy of the shock, while the remaining caused damage leaving a crater roughly of 40 × 10³ m³, and a 80 kt mass of the ground was ejected. The damage size and surface area have been estimated. The thermic was estimated to have ∼100 m horizontal size, ∼46 m/s speed of its ascending, and a 1.6 min time of the ascent up to the maximum altitude of approximately 4 km. At a distance of 250 km, near Cyprus, the intensity of sound was estimated to be no less than 76 dB. The shock wave traveling upwards caused significant disturbance in the atmosphere and geospace. The increase in the pressure caused by the wave is estimated to be dozens of percent in a 86–90 km altitude range. Shock wave dissipation in the 80–90 km altitude range could cause atmospheric heating by 10–20% and the generation of AGWs with δ_p ∼ 0.1 propagating to distances of thousands of kilometers from the epicenter. The secondary waves, on account of the dynamo effect, could generate periodic variations in the geomagnetic field with an amplitude of 0.1–0.3 nT.