The Chicxulub impact triggered a mega-earthquake lasting weeks or months

Oct. 7 () –

New evidence suggests that the Chicxulub impact, which wiped out the dinosaurs, also triggered an earthquake so massive that rocked the planet for weeks or months after the collision.

The amount of energy released in this “mega-earthquake” it is estimated at 10 to the 23 joules, which is about 50,000 times more energy than that released in the magnitude 9.1 Sumatra earthquake in 2004, according to Hermann Bermúdez, of Montclair State University, in a paper being presented at the Geological Society of America meeting (GSA Connects 2022).

Earlier this year, Bermúdez visited Cretaceous-Paleogene (K-Pg) mass extinction event boundary outcrops in Texas, Alabama, and Mississippi to collect data, complementing her previous work in Colombia and Mexico documenting evidence of catastrophic impact.

In 2014, while conducting fieldwork on Colombia’s Gorgonilla Island, Bermúdez found spherule deposits: layers of sediment filled with tiny glass beads (up to 1.1mm) and fragments known as “tektites” and “microtektites.” that were ejected into the atmosphere during an asteroid impact. These glass beads formed when heat and pressure from the impact melted and dispersed the Earth’s crust, ejecting tiny molten droplets into the atmosphere. which then fell to the surface as glass under the influence of gravity.

The exposed rocks on the coast of Gorgonilla Island tell a story from the bottom of the ocean, approximately 2 km deep. There, about 3,000 km southwest of the impact site, sand, mud and small ocean creatures were accumulating on the ocean floor when the asteroid hit. Mud and sandstone layers up to 10 to 15 meters below the sea floor experienced deformation of soft sediments that are preserved in outcrops today, which Bermúdez attributes to the shock of the impact.

Faulting and deformation due to shaking continue through the spherule-rich layer that was deposited after the impact, indicating that shaking must have continued during the weeks and months it took for these finer-grained deposits to reach bottom. of the ocean. Just above those spherule deposits, the preserved fern spores they mark the first recovery of plant life after the impact.

Bermúdez explains in the abstract: “The section that I discovered on Gorgonilla Island is a fantastic place to study the K-Pg boundary, because it is one of the best preserved and is found deep in the ocean, so it was not affected by the tsunamis.

Evidence of the deformation of the mega-earthquake in Mexico and the United States is also preserved. At the El Papalote exhibit in Mexico, Bermúdez observed evidence of liquefaction, when a strong shake causes water-saturated sediments to flow as a liquid.

In Mississippi, Alabama, and Texas, Bermúdez documented faults and cracks likely associated with the mega-earthquake. He also documented tsunami deposits in various outcrops, left behind by a huge wave that was part of the cascading catastrophes resulting from the asteroid collision.