What would be most dangerous, if an asteroid hits the Earth?

Courtesy: American Geophysical Union release

If an asteroid struck Earth, which of its effects—scorching heat, flying debris, towering tsunamis—would claim the most lives? A new study, published in Geophysical Research Letters and described as the first to look at all seven impacts of dangerous asteroids,  has the answer: violent winds and shock waves are the most dangerous effects produced by Earth-impacting asteroids. Shock waves arise from a spike in atmospheric pressure and can rupture internal organs, while wind blasts carry enough power to hurl human bodies and flatten forests.

The study explored seven effects associated with asteroid impacts—heat, pressure shock waves, flying debris, tsunamis, wind blasts, seismic shaking and cratering—and estimated their lethality for varying sizes. The researchers then ranked the effects from most to least deadly, or how many lives were lost to each effect. According to the scientists, this is the first study that looks at all seven impact effects generated by hazardous asteroids and estimates which are, in terms of human loss, most severe.

Overall, wind blasts and shock waves were likely to claim the most casualties, an AGU release citing the study says. In experimental scenarios, these two effects accounted for more than 60% of lives lost. Shock waves arise from a spike in atmospheric pressure and can rupture internal organs, while wind blasts carry enough power to hurl human bodies and flatten forests.

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Thankfully, it does not happen too often. The lead scientist Clemens Rumph, a Marie Curie Senior Research Assistant within Engineering and the Environment at the University of Southampton, also reported in another paper accepted for publication in Meteoritics and Planetary Science on 04 February 2017 that “an asteroid impact is a low probability event with potentially devastating consequences.”

And that “the Asteroid Risk Mitigation Optimization and Research (ARMOR) software tool calculates whether a colliding asteroid experiences an airburst or surface impact and calculates effect severity as well as reach on the global map. To calculate the consequences of an impact in terms of loss of human life, new vulnerability models are derived that connect the severity of seven impact effects (strong winds, overpressure shockwave, thermal radiation, seismic shaking, ejecta deposition, cratering and tsunamis) with lethality to human populations. With the new vulnerability models ARMOR estimates casualties of an impact under consideration of the local population and geography. The presented algorithms and models are employed in two case studies to estimate total casualties as well as the damage contribution of each impact effect. The case studies highlight that aerothermal effects are most harmful except for deep water impacts, where tsunamis are the dominant hazard. Continental shelves serve a protective function against the tsunami hazard caused by impactors on the shelf. Furthermore, the calculation of impact consequences facilitates asteroid risk estimation to better characterize a given threat and the concept of risk as well as its applicability to the asteroid impact scenario are presented. “

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