Mystery still surrounds 1908 Tunguska event

Regardless of the details, the influence of the Tunguska event is still felt. Research papers on the subject continue to be published.

Today, astronomers also peer into the skies with powerful telescopes to look for signs that rocks with the potential to cause a similar event are heading our way, and to assess the risk that they pose.

    When a Tunguska type event happens again, the overwhelming probability is that it will happen nowhere near human population

In 2013 in Chelyabinsk, Russia, a relatively small meteor around 62ft (19m) wide created visible disruption. This surprised researchers like Collins. His models had predicted it would not cause as much damage as it did.

"What's challenging is that this process of the asteroid disrupting in the atmosphere, decelerating, evaporating and transferring its energy to the air, is a very complicated process. We would like to understand it more, to better predict consequences of these events in future."

Chelyabinsk-sized meteors were previously believed to occur roughly every 100 years, while Tunguska-sized events had been predicted to occur once a millennium. This figure has since been revised. Chelyabinsk-sized meteors could be happening 10 times more frequently, says Collins, while Tunguska style impacts could occur as often as once every 100-200 years.

Unfortunately, we are and will remain defenceless against similar events, says Kvasnytsya. If another explosion like the Tunguska event took place above a populated city, it would cause thousands if not millions of casualties, depending where it hit.

But it is not all bad news. The probability of that happening is extremely small, says Collins, especially given the huge surface area of Earth that is covered in water. "When a Tunguska-type event happens again, the overwhelming probability is that it will happen nowhere near human population."

We may never find out whether the Tunguska event was caused by a meteor or comet, but in a way that does not matter. Either could have resulted in the intense cosmic disruption, which we are still talking about over a century later.

Melissa Hogenboom is BBC Earth's feature writer. She is @melissasuzanneh on Twitter.

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