Earth was still a violent place shortly after life began, with regular impactors arriving from space. For the first time, scientists have modeled the effects of one such violent event — the strike of a giant asteroid. The effects were so catastrophic that, along with the large earthquakes and tsunamis it created, this asteroid may have also set continents into motion.
The asteroid to blame for this event would have been at least 37km in diameter, which is roughly four times the size of the asteroid that is alleged to have caused the death of dinosaurs. It would have hit the surface of the Earth at the speed of about 72,000kmph and created a 500km-wide crater.
At the time of the event, about 3.26 billion years ago, such an impact would have caused 10.8 magnitude earthquakes — roughly 100 times the size of the 2011 Japanese earthquake, which is among the biggest in recent history. The impact would have thrown vaporized rock into the atmosphere, which would have encircled the globe before condensing and falling back to the surface. During the debris re-entry, the temperature of the atmosphere would have increased and the heat wave would have caused the upper oceans to boil.
Donald Lowe and Norman Sleep at Stanford University, who published their research in the journal Geochemistry, Geophysics, Geosystems, were able to say all this based on tiny, spherical rocks found in the Barberton greenstone belt in South Africa. These rocks are the only remnants of the cataclysmic event.
However, despite providing such rich details about the impact, Lowe and Sleep are not able to pinpoint the location of the impact. It would be within thousands of kilometers of the Barberton greenstone system, but that is about all they can say. The exact location may not be that important, Lowe argued: "With this study, we are trying to understand the forces that shaped our planet early in its evolution and the environments in which life evolved."
However, according to Redfern: "Even with a hot mantle you would need something to destabilize the crust." And it is possible that an asteroid impact of this magnitude could have achieved that.
