Probabilistic assessment of Tunguska-scale asteroid impacts

Abstract

The Tunguska meteor airburst has been extensively studied and modeled in attempts to deduce its size, properties, and impact characteristics. However, most of the existing modeling and simulation studies have investigated a small subset of cases based on assumptions of representative densities, velocities, or other properties. In this study, we use a probabilistic asteroid impact risk model to assess the entry, burst, and ground damage from 50 million Tunguska-scale asteroid impacts, covering a full range of potential impactor properties. The impact cases are sampled from probabilistic distributions representing our current knowledge of asteroid properties, entry trajectories, and size frequencies. The results provide a broader characterization of the range and relative likelihood of asteroid properties that could yield Tunguska-scale impacts. Results show that Tunguska-like events can be produced by a broad range of impact scenarios, and prevailing size and energy estimates of 50–80 m or 10–20 Mt remain within the relatively likely property ranges. However, our results suggest that objects with slightly larger initial energies of 20–30 Mt and diameters 70–80 m are more likely to cause Tunguska-scale damage areas than objects on the smaller end of the potential size range. Even when relative size frequencies are accounted for, the greater damage potential of larger objects outweighs their rarity, while the low damage potential of small objects counteracts their frequency.