Asteroid impacts are, with good reason, seen as unstoppable catastrophes, but until now it wasn’t clear which of their effects would be the deadliest. A new study has solved this morbid question – researchers think that the violent winds and shock waves are by far the most dangerous consequences of a cosmic impact, accounting for 60 percent of deaths.
“The likelihood of an asteroid impact is really low,” lead author Clemens Rumpf, from the University of Southampton, said in a statement. "But the consequences can be unimaginable."
He added: “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."
The seven effects studied by the team were wind blasts, overpressure shocks, thermal radiation, cratering, seismic shaking, ejecta deposition, and tsunamis. The new research, published in Geophysical Research Letters, used a simulation that hurled a total of 50,000 artificial asteroids with a diameter between 15 and 400 meters (49 and 1,312 feet). Using the simulated impacts, researchers estimated how many lives would be lost due to each of the seven effects.
The researchers discovered that land-based impacts were about 10 times more dangerous than asteroids that take a dive in the ocean. Tsunamis only account for 20 percent of the lives lost, due to the loss of energy from a tidal wave moving towards the coast or how a population is distributed in coastal communities.
Quakes generated from an impact are almost negligible. Only 0.17 percent of the deaths are caused by them. Only slightly more important are the cratering and airborne debris, with 1 percent of the deaths.
Significantly more dangerous is the heat of the bolide, which would account for 30 percent of lives lost, although underground shelters or basements could protect people. The values are averages of all the different scenarios, and while they don’t predict exactly what’s going to kill people in a specific location, they do provide a statistically backed strategy to deal with the asteroid threat.
The analysis is valid for asteroids as big as 400 meters, and it shows that only asteroids bigger than 18 meters are lethal. If we were to know that an asteroid was on its way and we could work out where it was going to land, this study would give us a good idea of whether to fight it off or let it hit (obviously moving people at risk out of the danger zone).
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