Austin Forum hosted Dr. Sean Gulick who has been studying the region of Chicxulub crater, which was created when a gigantic meteor rocketed down from the sky and plummeted into the ocean near the Yucatán Peninsula in Mexico 65.5 million years ago. After contemplating the damage done by this massive space rock, you don’t need to have specialized knowledge about rocks, craters, or geology to understand that stray asteroids slamming into the earth are Bad News and that humanity has got to send a contingent of explorers and colonizers off this planet before another event of this nature occurs, potentially bringing on the extinction of our species.
Dr. Sean Gulick in Progresso, Mexico, near the Chicxulub Impact Crater (from UT Austin’s Institute for Geophysics.
We live in denial about how fragile life on Earth is. Viewed from a human scale, the planet seems so big, eternally rotating, tilting, seemingly stable, predictable. Sadly, we Earthlings are not spinning around in the best of neighborhoods. Dr. Gulick showed a slide covered with black dust specks: each speck represented a hunk of space junk whizzing around in our solar system, many with the potential to slam into Earth and rock our world. Literally.
It took a long time for geologists to discover the giant depression in the ocean floor now known as the Chicxulub impact crater. When it was found, hopeful entrepreneurs drilled the area, seeking oil. What they found instead was evidence that an extraterrestrial rock landed there, putting a violent and sudden end to the age of the dinosaurs and driving the planet from the Cretaceous period into the Paleogene period. Scientific evidence has proved that the sudden mass extinction at the end of the Cretaceous period was caused by a single event: a destructive meteor.
When you view a virtual model of a relatively small hunk of rock hitting a planet, it does not seem like a meteor could cause that much damage. Earth, huge; meteor rock, comparably small. However, the asteroid that made the Chicxulub crater was large: 10 kilometers, or six miles, wide.
One way to measure how big a meteor was was is to consider how deep its impact was on the earth. This could be phrased as, “How big a hole did it punch into the earth?” The “transient” crater — the first impact of the crater, before the earth affected by the impact melted, uplifted, and froze in time with the top layer rolling over into the crater — was probably 35 kilometers deep and 100 kilometers across.
But it’s not all about meteor size and the crater it creates: a crater’s impact on the earth transfers extraordinary kinetic energy to the planet. The Chicxulub asteroid was moving about 22 kilometers per second, or 50,000 miles per hour. When it hit Earth, about 1% of the energy of the impact was displaced into tsunamis and hurricane force winds. The other 99% of the energy was directed into its target: Mother Earth.
Dr. Gulick described that energy force as equal to 13 earthquakes combined. The heat from the blast cooked anything within 750 miles. Millions of glassy balls of molten impact material rained death on every living thing, from dinosaurs to trees, as the rocks and earth became suddenly fluid, like water, under the extreme forces when the two space objects – earth and meteor – collided. Particulate matter was thrown into the earth’s atmosphere, turning day into night and plunging the planet into a three-year global winter. World-wide darkness suppressed photosynthesis and collapsed food chains.
Dr. Gulick pointed out that the “ejecta” was worse than the impact itself. The matter that was thrown into the air increased the sulfur content of the atmosphere, caused acid rain, emitted infrared rays that heated up the nearby atmosphere like a pizza oven, and changed the chemistry of the ocean, causing mass extinction.
The meteor killed off most of the life on Earth. What survived after that massive storm of destruction were significantly smaller life forms, such as the mammals who evolved into humans.
We have to get to know impact craters and the meteors that cause them much better, because there is a chance that one day a meteor will end life as we know it — again. The meteor that slammed into the Chixculub Crater may have resulted in humans as top dog on Earth, but the only constant in life is change.
This UT Austin Forum presentation was sponsored by the Texas Advanced Computer Center (TACC). Big, big data needs to be analyzed to learn about our planet’s prior experiences with meteors, about crater impacts on other planets, and about the meteors that are careening around in space, possibly on a path to slam into the earth in the future.
Did anyone have a clue that a meteor was about to smash into Russia in February, the largest to hit the planet in more than 100 years? Nope. Let’s put some funding into meteor detection and deflection. Consider the footage taken in Russian Urals region. If what happened in Russia in 2013 were to happen over a metropolitan area, it would be a major catastrophe. At it was, it caused extraordinary damage, injured more than 1,000, and for a brief time emitted light that was brighter than the sun. (See Wiki on Chelyabinsk meteor.)
Although there are less of these impact events on Earth now than say, 65.5 million years ago, we don’t see near as many craters than we should. For an idea of what’s really going on, take a gander at the moon. Heck, there’s so many impact craters that the scientists give them names.
Russian Urals region meteor crater: recovered rock could be part of the Chelyabinsk meteor. Pix from Daily Mail, UK.
Compare earth and our lunar companion: the moon looks like a teenager’s skin under a harsh light. One reason we don’t see big impact craters on the earth’s surface is because the surface is constantly changing. And by constantly changing, Dr. Gulick means every 200 million years or so, give or take 50 million, when the tectonic plates shift around, effectively covering up impact craters. Space junk was smacking into us at a higher order of magnitude then than now, but the evidence has been swept under the oceanic plates.
Chicxulub is the only confirmed “extinction” crater on the planet: ground zero for the end of the non-avian dinosaurs. Not that there have not been other mass extinctions. In fact, there have been four or five of them. There are theories that acidification of the ocean – similar to the ocean changes observed by scientists today – might be the cause of some earlier planetary extinctions. But that is the subject of some other blog post.
Sleep soundly if you can, as you consider that before another 45 million years pass, it’s likely this planet will be hit with another extinction-producing asteroid….anytime in the next 45 million years. Maybe tonight.
A scientist could into detail about the carbonates, the enhanced dissolution, impact melt, mega blocks, crater seismic gravity, magnetic wells, melt sheets, gravity anomalies, distinct ejecta distribution patterns, velocity models…gigapascals…tons of gigapascals… but this part was way over my head.
But…fireball layer! That, I can picture.
Actually, I didn’t picture it quite like Dr. Gulick’s slide. I was picturing something more like the Burning Man fireball.
The catastrophic events that follow a massive meteor impact are unimaginable – except to scientists, who created an animated movie of the global catastrophe combined with scary music. Thankfully, the clip does not depict balls of hellfire raining doomsday on screaming tyrannosaurs, raptors, and sauropods.
In the next two years, the scientists involved in the study of the Chicxulub impact crater plan a drilling expedition to the location. They are interested in what kind of material will be found deep in the crater. It was incredibly hot at the Chicxulub area for about two million years. Life forms evolved in the thermal springs: what must they have been like?
The scientists also want to perform studies comparing the Chicxulub crater with craters on other planets. There will be opportunities for teachers and other researchers to participate in these future studies. If you want to get involved, contact Dr. Gulick.
And what blog posting about the end of the Age of Dinosaurs would be complete without a happy moment spent watching Godzilla dancing?
Event: “The 65.5 Million Year Old Chicxulub Impact Crater: Insights into Planetary Processes, Extinction and Evolution” presented by Dr. Sean Gulick, Research Associate Professor, Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin.
About the speaker: Dr. Sean Gulick is a research associate professor in the Institute for Geophysics at The University of Texas at Austin. His primary scientific interest is the examination of deformation of the Earth. Current projects include examining tectonic and glacial climate linkages in Alaska, investigations of geophysical images of the Chicxulub impact crater, and many others. To learn more about these projects: www.ig.utexas.edu/people/staff/sean.
Update: The team blogged their expedition and research on location, which came to a close in in 2016: https://esoexpedition364chicxulubimpactcrater.wordpress.com.
Links for more information
About the Austin Forum: The Austin Forum is a monthly speaker series and networking event that hosts distinguished leaders who share their knowledge and experience about the confluence of science, technology and society in the 21st century. For more information see their website. http://www.austinforum.org/
For more information about the Texas Advanced Computing Center (TACC): http://www.tacc.utexas.edu/
For general info on the Chiczulub crater, see: