One of the planet’s worst days ever occurred around 66 million years ago when a massive asteroid hit Earth and wiped out most life, including dinosaurs. Now, a new study has identified more evidence of dire consequences.
The aftermath of the asteroid impacting the Earth caused tsunamis across the planet more than 1km high and massive earthquakes that followed for many months.
The Cretaceous came to an abrupt end when a 10 km long asteroid crashed into what is now the Yucatan Peninsula in Mexico. It has caused a series of environmental disasters including earthquakes, tsunamis, volcanic eruptions and wildfires around the world. The oceans became too acidic for many life forms, and large amounts of soot and rock were blown into the atmosphere, blocking sunlight for 18 months. This event disrupts photosynthesis, kills plants, and causes food chains to collapse.
Ultimately, this event caused the extinction of about three-quarters of life on Earth, most notably dinosaurs, about 93% of mammals, and most marine life. Increasingly, scientists are finding concrete evidence of what happened immediately after the impact, including the fish carcass being thrown out of the water and suffocating in a rain of molten glass. Two new studies have found further evidence of the devastation that followed.
Super Tsunami
First, scientists at the University of Michigan created a global simulation of the tsunami that occurred after the impact, backing it up with analysis of geological records from 120 locations around the world.
Simulations built on data from previous studies simulated a 14 km wide asteroid traveling at 43,200 km/h hitting a granite crust covered with thick sediments and oceans. farm. From there, the team was able to monitor the waves generated in the minutes and hours after the collision.
Within the first three minutes, a 4.5-kilometer wall of water was formed from ejected material, which rapidly fell back to the surface. Ten minutes after impact, an annular tsunami 1.5 km high began to sweep across the ocean.
After an hour, the tsunami passed from the Gulf of Mexico into the North Atlantic Ocean, reaching the Pacific Ocean after four hours. At 24 hours, the waves have essentially circumnavigated the globe, crossing the Pacific Ocean from the east and the Atlantic Ocean from the west to meet in the Indian Ocean from both sides.
These simulations are backed up by geological record analysis. The team examined sedimentary layers deposited around the K-Pg boundary in the late Cretaceous and found a large number of sites with discontinuous boundaries in the North Atlantic and South Pacific Oceans. , indicating that the tsunami hit these areas hardest. In contrast, the South Atlantic, North Pacific, Indian and Mediterranean oceans had the least disruption.
But of course, the effects last much longer.
Huge earthquake
The second study provides evidence of a large earthquake that shook the planet weeks or even months after the initial impact. Geologist Hermann Bermúdez examined in detail the rocky outcrops in Colombia, Mexico and the United States that preserve the K-Pg boundary.
On the island of Gorgonilla, Colombia, about 3,000 km southwest of the impact site, Bermúdez noticed layers of mud and sandstone showing signs of soft sediment deformation. This is thought to be shaking from the earthquakes immediately following the impact.
However, there are also signs it is continuing to rumble for longer. At the boundary, he also found a layer of spherical, tiny glass beads that are a gun that sucks up the asteroid’s impact. The heat and pressure from a collision melt and disperse material from the crust into the atmosphere, where it rains back into glass.
The spherule class on the island of Gorgonilla
It will take weeks or months for this spherule on Gorgonilla Island to form, as it must have settled to the ocean floor about 2 km. And yet, the spherule layer is also fractured and deformed. It shows that earthquakes have continued to shake the ground for a long time after impact.
At sites in the US, Bermúdez found similar faults and cracks likely arising from a major earthquake, while sites in Mexico showed signs of liquefaction, which occurs when strong shaking causes The mud comes out more like a liquid.
Bermúdez estimates the quake will release about 10^23 joules of energy. That’s about 50,000 times more energy than the 9.1-magnitude earthquake that struck the Indian Ocean in 2004.
Taken together, these two studies help to describe in more detail and vividly the day of the terrible destruction 66 million years ago.
The tsunami study has been published in the journal AGU Advances, while Bermúdez will present his findings on the major quake at the Geological Society of America (GSA) meeting in October.
