Asteroid collision triggered a months-long mega-earthquake

Sixty-six million years ago, a massive asteroid struck the Earth, leading to the extinction of dinosaurs and many other animal and plant species. According to a new study led by Hermann Bermúdez, a doctoral student in Paleontology at the National University of Colombia, this asteroid impact also triggered an earthquake so massive that it shook our planet for weeks to months after the collision. The amount of energy released by this mega-earthquake is estimated at 10²³ joules – about 50,000 times more energy than that released in the magnitude 9.1 Sumatra earthquake in 2004, one of the most devastating earthquakes in modern history.

In 2014, while doing field work on the Gorgonilla Island in Colombia, Bermúdez discovered several spherule deposits – layers of sediment filled with small glass beads and shards known as “tektites” and “microtektites” which were ejected into the atmosphere during the asteroid impact. The spherules formed when the heat and pressure of the impact melted and scattered the Earth’s crust, ejecting tiny, melted blobs into the atmosphere that, later on, under the influence of gravity, fell back to the surface of the Earth as glass.

Moreover, about 3,000 kilometers southwest of the impact, layers of mud and sandstone as far as 10 to 15 meters below the seafloor experienced soft-sediment deformation that is still preserved today. These deformations – which continue up through the spherule-rich layer which was deposited post-impact – were likely caused by a massive earthquake which must have continued for weeks or even months after the asteroid collision. 

Finally, evidence of deformation from the mega-earthquake are also preserved in Mexico and the United States. For instance, at the El Papalote exposure site in Mexico, Bermúdez found evidence of liquefaction – a process caused by strong shaking, making water-saturated sediments to flow like a liquid. In Mississippi, Alabama, and Texas, the paleontologist also documented faults and cracks most likely associated with the mega-quake. 

The study will be presented at the Geological Society of America (GSA) Connects meeting in Denver on Sunday, October 9, 2022.

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By Andrei Ionescu, Earth.com Staff Writer