The frequency of window damage caused by bolide airbursts: A quarter century case study |
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| Authors: | Nayeob Gi Peter Brown Michael Aftosmis |
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| Affiliation: | 1. Department of Earth Sciences, University of Western Ontario, London, Ontario, N6A 3K7 Canada;2. Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7 Canada
Centre for Planetary Science and Exploration, University of Western Ontario, London, Ontario, N6A 5B7 Canada;3. Computational Aerosciences, NASA Advanced Supercomputing Division, NASA Ames Research Center, Moffett Field, California, 94035 USA |
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| Abstract: | We have empirically estimated how often fireball shocks produce overpressure (?P) at the ground sufficient to damage windows. Our study used a numerical entry model to estimate the energy deposition and shock production for a suite of 23 energetic fireballs reported by U.S. Government sensors over the last quarter century. For each of these events, we estimated the peak ?P on the ground and the ground area above ?P thresholds of 200 and 500 Pa where light and heavy window damage, respectively, are expected. Our results suggest that at the highest ?P, it is the rare, large fireballs (such as the Chelyabinsk fireball) which dominate the long-term areal ground footprints for heavy window damage. The height at the fireball peak brightness and the fireball entry angle contribute to the variance in ground ?P, with lower heights and shallower angles producing larger ground footprints and more potential damage. The effective threshold energy for fireballs to produce heavy window damage is ~5–10 kT; such fireballs occur globally once every 1–2 years. These largest annual bolide events, should they occur over a major urban center with large numbers of windows, can be expected to produce economically significant window damage. However, the mean frequency of heavy window damage (?P above 500 Pa) from fireball shock waves occurring over urban areas is estimated to be approximately once every 5000 yr. Light window damage (?P above 200 Pa) is expected every ~600 yr. |
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