What happened when a rock the size of London hit the earth?

Scientists have found that a giant meteorite first discovered in 2014 triggered a tsunami larger than any in known human history and caused the oceans to boil.

The space rock, 200 times the size of the one that wiped out the dinosaurs, slammed into Earth three billion years ago, when our planet was still in its infancy.

Armed with sledgehammers, scientists trekked to the impact site in South Africa to chisel away boulders to understand the crash.

The team also found evidence that massive asteroid impacts not only caused destruction on Earth, but also helped early life thrive.

“We know that after the Earth was formed, there was still a lot of debris flying through space that would impact Earth,” says Prof. Nadja Drabon of Harvard University, lead author of the new research.

“But now we’ve found that after some of these massive impacts, life was really resilient and actually flourished and thrived,” she says.

The S2 meteorite was much larger than the space rock we know best. The one that led to the extinction of the dinosaurs 66 million years ago was about 10 km wide, or almost as high as Mount Everest.

But S2 was 40-60 km wide and its mass was 50-200 times larger.

It struck when Earth was still in its infancy and looked very different. It was a water world with only a few continents sticking out of the sea. Life was very simple – microorganisms made up of single cells.

The impact site in the eastern Barberton Greenbelt is one of the oldest sites on Earth with remnants of a meteorite impact.

Prof. Drabon traveled there three times with her colleagues, driving as far into the remote mountains as possible before walking the rest of the way with backpacks.

Rangers accompanied them with machine guns to protect them from wild animals such as elephants or rhinos or even poachers in the national park.

They looked for bullet particles or tiny rock fragments left behind from the impact. Using sledgehammers, they collected hundreds of kilograms of rock and brought it back to the laboratories for analysis.

Prof. Drabon stowed the most valuable items in her luggage.

“I usually get stopped by security, but I tell them a lot about how exciting science is and then they get really bored and let me pass,” she says.

The team has now reconstructed exactly what the S2 meteorite was doing when it violently smashed into the Earth. It hollowed out a 500 km crater and pulverized chunks of rock that were thrown out at incredibly high speeds, forming a cloud that circled the globe.

“Imagine a rain cloud, but instead of water droplets falling, it’s as if molten rock droplets are raining from the sky,” says Prof. Drabon.

A huge tsunami would have swept across the globe, tearing up the ocean floor and flooding the coasts.

The 2004 Indian Ocean tsunami would have paled in comparison, says Prof. Drabon.

All this energy would have generated enormous amounts of heat, boiling the oceans and evaporating up to tens of meters of water. It would also have increased the air temperature by up to 100°C.

The sky would have turned black and full of dust and particles. Without sunlight penetrating the darkness, simple life on land or in shallow water that relies on photosynthesis would have been wiped out.

These impacts are similar to what geologists have found about other large meteorite impacts and what was suspected for S2.

But what Prof. Drabon and her team discovered next was surprising. The rock evidence showed that the violent disturbances had stirred up nutrients such as phosphorus and iron that fed simple organisms.

“Life was not only resilient, but actually recovered and thrived very quickly,” she says.

“It’s like brushing your teeth in the morning. It kills 99.9% of the bacteria, but in the evening they’re all back, right?” she says.

The new findings suggest that the large impacts acted like a giant fertilizer, transporting vital ingredients like phosphorus around the globe.

The tsunami that swept across the planet would also have brought iron-rich water from the depths to the surface, giving early microbes additional energy.

The findings underscore the growing view among scientists that early life was actually boosted by the violent succession of rocks hitting Earth in its early years, says Prof. Drabon.

“It appears that post-impact life actually found really favorable conditions that allowed it to flourish,” she explains.

The results are published in the scientific journal PNAS.