The Chicxulub Event - The Dinosaur Killer
Roughly 65.5 million years ago, a 10 km wide asteroid travelling at 10 km/s slammed into what is now known as the tip of the Yucatan Peninsula, Mexico, creating a crater more than 180 km in diameter and 60 km deep. The impact released an estimated 4x1023 Joules of energy (100 000 000 megatons of TNT equivalent). To put this in perspective, the most powerful man-made bomb ever detonated was the Tsar Bomb and was only 50 megatons. The Chicxulub event was 2 million times more powerful than the Tsar Bomb.
The impact caused the extinction of 65% of species and 35% of genera on the planet. It generated a fireball with a radius of 1000 km and caused an earthquake of magnitude 11.3 (extrapolating from an atomic bomb blast of magnitude 4). So much hot debris was ejected into the atmosphere that massive wildfires consumed much of the vegetation in North America, the Indian subcontinent, and the equatorial regions of the world. Huge amounts of nitrogen oxides released into the atmosphere would have fallen as acid rain, acidifying surface waters. Dust and soot from the impact would block sunlight, making photosynthesis difficult and creating an impact winter (like a nuclear winter, but for impacts) for several months to a decade. Once the dust settled out of the atmosphere, the remaining CO2 would lead to global warming for years. The asteroid landed in a shallow, tropical sea where the water is underlain by limestone (CaCO3). The impact would vapourize huge quantities of limestone, increasing atmospheric CO2 by maybe an order of magnitude. After the impact winter, the CO2 could have elevated average temperatures around the world by up to 10ºC.
A massive tsunami would also have been generated, with waves up to 2-3 km high. The shock waves generated by the impact set off global earthquakes and volcanic eruptions.
In March of 2010, 41 international experts from 33 institutions examined all the evidence from the past 20 years and came to the conclusion that the Chicxulub impact caused the K-T extinction, including the extinction of the dinosaurs.
