Wind kills. The most casualties from an asteroid impact won’t come from the impact itself. The wind, pressure and heat caused by the crash are far more dangerous, no matter where the asteroid hits.
Clemens Rumpf at the University of Southampton, UK, and his colleagues have calculated the mortality risk, should an asteroid hit a residential area. They considered asteroids that burn up completely, those that hit the ground, and those that strike in water. Surprisingly, the airborne side effects were the ones that cost the most lives.
As an asteroid hurtles towards the ground, it deposits a huge amount of energy into the atmosphere, resulting in a powerful shockwave, tornado-like winds and a plume of fire trailing behind it. When it crashes down, it forms a crater, shaking the ground around the impact and hurling debris into the air.
If the asteroid hits water (which is twice as likely as hitting land), it would create a tsunami, with waves reaching dozens of metres high. The farther from shore the impact is, the deeper the water and the taller the waves.
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