About 66 million years ago, a 10-kilometre asteroid hit Earth, leading to the extinction of the dinosaurs. The asteroid, known as the Chicxulub impactor, also triggered a ‘mega-earthquake’ that shook Earth for weeks to months after the collision, new research has found. Around 1,023 joules of energy are estimated to have been released during the ‘mega-earthquake’. This is about 50,000 times more energy than the amount released in the magnitude 9.1 Sumatra earthquake in Indonesia in 2004.
Columbian geologist Hermann Darío Bermúdez will present evidence of the ‘mega-earthquake’ at the GSA Connects meeting in Denver on Sunday, October 9 (Monday, October 10 in India).
How the research was conducted
Earlier this year, Bermúdez visited outcrops of the infamous Cretaceous-Paleogene (K-Pg) mass extinction event boundary in Texas, Alabama, and Mississippi to gather data. This supplemented his work in Colombia and Mexico documenting evidence of the catastrophic asteroid impact.
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It rained glass following the catastrophic asteroid impact
In 2014, Bermúdez found spherule deposits, which are layers of sediments filled with small glass beads and shards known as ‘tektites’ and ‘microtektites’. These glass beads are as large as 1.1 metres, a statement released by the Geological Society of America says. The ‘tektites’ and ‘microtektites’ were ejected into the atmosphere during an asteroid impact.
According to the statement, the glass beads formed when the heat and pressure of the impact melted and scattered the crust of Earth. After this, the small, melted blobs were ejected up into the atmosphere. These fell back to the surface of Earth as glass under the influence of gravity.
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Deformations on ocean floor indicate the occurrence of ‘mega-earthquake’
At the bottom of the ocean, roughly two kilometres down, mud, and small ocean creatures were accumulating at the ocean floor, about 3,000-kilometre southwest from the site of the impact. About 10 to 15 kilometres below the seafloor, layers of mud and sandstone experienced soft-sediment deformation that is preserved in the outcrops today. According to Bermúdez, the shaking of the impact resulted in the soft-sediment deformation.
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Since the faults and deformation due to shaking continue up through the spherule-rich layer that was deposited post-impact, the researchers concluded that the shaking must have continued for weeks and months. The finer-grained deposits reached the ocean floor for the same reason. The researchers found preserved fern spores above the spherule deposits, which could have been the first plant-life to have emerged after the impact.
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Other regions providing evidence for mega-earthquake
In the statement, Bermúdez said the section he discovered on Gorgonilla Island is a “fantastic” place to study the K-Pg boundary. This is because it is one of the best-preserved and was located deep in the ocean. Hence, it was not affected by tsunamis.
One can also find evidence of deformation from the mega-earthquake in Mexico and the United States. Bermúdez observed the evidence of liquefaction at the El Papalote exposure in Mexico. Liquefaction is the phenomenon when strong shaking causes water-saturated sediments to flow like a liquid.
In Mississippi, Alabama, and Texas, Bermúdez found faults and cracks likely associated with the mega-earthquake.
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