Risks for poisoning of coastal and inland population due to asteroid impacts in Southern regions of Black Sea

Abstract

The hydrogen sulfide rich waters of the Black Sea pose a potential danger for the surrounding land regions. The impact of an asteroid exceeding tens of meters in size may cause both a tsunami wave and a catastrophic poisonous gas release in the atmosphere. Some effects of this last phenomenon on the Southern Black Sea coastal regions are evaluated in this paper. The initial surface area of the poisonous cloud depends on asteroid size. The initial thickness of the cloud depends, in addition, on sea depth at impact location. The wind speed plays an important role in H2S cloud dynamics. At 10 m/s wind speed, the cloud margins reach 185 km from the impact location in about 3 h. The maximum distance traveled by the hydrogen sulfide cloud increases by increasing the asteroid size and wind speed. The influence of the impact position on the distance traveled by hydrogen sulfide clouds is rather weak, as long as the seawater depth does not change significantly. The land surface area covered by the H2S cloud generated by a 1,000 m size asteroid ranges between about 6,400 and 12,000 km2. This may affect up to 3,000,000 people. When a 250 m size asteroid is considered, the covered land surface area ranges between about 1,400 and 2,100 km2 and up to 120,000 people may be affected. In case of a 70 m size asteroid, the cloud covers up to 280 km2 of land. This may affect up to about 70,000 people. These evaluations do not include the population of the towns on or near the seashore. A simple methodology to estimate the environmental risks of the potential asteroid impact was proposed. Sites less than 160 km from the impact place are at risk.