Incoming: The Chicxulub Impactor, Part 3 ― The Impactor & Effects
By Stephanie Osborn
Based on the evidence at the impact site, there are quite a few things that can be fairly readily extrapolated about the impactor.
- Impactor’s estimated velocity: 12.6-73km/s (4,500-26,000km/hr or 2,800-16,300mph)
- Impactor’s estimated diameter: 9-11km (~5.5-6.8mi) up to 81km (50mi)
- Impactor’s estimated mass: 0x1015-4.6×1017kg (2.2×1015-1.0×1018lb)
The generally held view is that the impactor was an asteroid about 10km (6mi) in diameter, traveling at 16-32 km/sec (10-20 miles/sec, or 36,000-72,000mph).
So the impactor comes screaming in at anywhere from 2,800 to as high as 16,000 miles an hour, doesn’t even notice the top, oh, 290 miles of atmosphere, and that last 10 miles of air doesn’t even slow it down. Nor does the relatively shallow water in which it impacts, which, 65 million years ago, covered the entire site.
When the impactor contacted Earth’s surface, it still didn’t slow down, at least not initially. Instead, it punched several miles into the rock. The sudden impact vaporized the impactor as well as substantial quantities of ocean basin and underlying bedrock. Additional quantities of Earth’s crust were liquified and sent into exoatmospheric, suborbital trajectories, only to fall back down, far far away from where it started. Some was probably ejected from its home planet entirely. And the remaining bedrock of the entire region was shattered like fragile glass.
- Original crater depth: several miles (exact depth not yet determined; possibly as deep as 25-30mi, per Gulick, et al.)
- Original crater diameter: 185km (115mi); some estimate 300km (186mi)
- Temperatures at ground zero: >>10,000ºF, possibly as much as 18,000ºF (~10,000ºC)
- Yield/KE of impact: at least 1.1×108-1.6×108MT or over 100,000GT
By comparison, the biggest nuke ever detonated on Earth, Tsar Bomba, was 50MT. The Chicxulub impact was, at these numbers, 2 million times as powerful as Tsar Bomba.
The Thermal Blast
If you were close enough to see the impact, it would have been the last thing you ever saw. All life within 1,000km (625mi) would have been incinerated in under 10 seconds.
The Atmospheric Shock Wave
- Local winds: 900-1000 km/hr (560-625mph)
- Air blast damage radius: 900-1800km (560-1120mi)
- Sound of impact: at least 105+ decibels
- Megatsunami height range estimates: 50-305m (~165-1,000ft) [Note that these estimates depend on a given researcher’s initial conditions, therefore the estimates vary widely.]
- Estimated inland reach: >100km (62mi)
The Seismic Seiche
A seiche is a localized tsunami-like wave akin to a “bathtub slosh.” It is usually generated by the local arrival of one or more earthquake waves.
Extrapolating from the 2011 quake in Tohoku, Japan (mag~9.2), which generated a 1.5m (~5ft) seiche, we can estimate that the seismic waves from the Chicxulub impact generated seiches of 10-100m (33-330ft).
Released Greenhouse Gases
Estimated released greenhouse gases:
- Carbon dioxide, CO2: ~10 trillion tons (10,000,000,000,000 tons)
- Carbon monoxide, CO: ~100 billion tons (100,000,000,000 tons)
- Methane, CH4: ~100 billion tons (100,000,000,000 tons)
And methane is flammable, in itself.
Core drilling on the peak ring of the crater showed that the topmost layer of debris laid down in the aftermath contained a significant amount of organic material, topped by bits of charcoal; evidently there were significant fires ignited worldwide, and the first days after the cataclysm may well have been a firestorm in many, if not most, places.
After the fires died down, Earth would have entered a “nuclear” winter for at least a year and possibly up to several decades after the impact, thanks to all of the particulate material (dust, soot, smaller ejecta) which was injected into the stratosphere, that then blocked the sunlight. Researchers estimate global temperatures decreased by 2-3ºC (3.5-5.5ºF); some areas dropped as much as 8ºC (14.5ºF). Photosynthesis largely ceased worldwide; plants began to die. As a consequence, herbivores began to starve; subsequently, predators began to starve. The last to die would, presumably, have been the scavengers, though based on the information coming out of the Tanis/Hell Creek dig, no one lasted long enough for there to be a lot of scavenging.
But ash is particulate, and eventually the ash will precipitate out of the atmosphere.
Some of this stratospheric material was in the form of sulfur and nitrogen compounds; as it gradually settled and fell out of the atmosphere, it formed acid rain.
Then the released greenhouse gases took over, and the low temperatures started to soar. This may have lasted for as long as 200,000 years after the K-T boundary.
It gets worse.
Some scientists speculate that such large impacts may generate magma plumes on the antipodal (opposite) side of Earth in the long term. This is generally not considered probable by mainstream researchers. It must be admitted, however,, that the shock waves would indeed converge on the opposite side of the planet; whether it created additional problems or not would likely depend upon the magnitude/amplitude of the shock waves, and whether the timing was such that they interfered constructively or destructively. In any case, the shock waves probably set off existing volcanoes, in a kind of planetary paroxysm.
It is flagrant, screaming understatement to say that the aftermath would not have been pleasant for any survivors.
Next up: What, where, and how hard?
For more details, check out INCOMING! The Chicxulub Impactor by Stephanie Osborn on Kindle and Nook.
And check out Stephanie’s fiction!
IS SOMEONE TRYING TO KILL MARY RAO?
Captain Mary Rao, Jablonka’s planetary tactical officer, seems to be under the gun from all angles, but neither the Sigurdsen Base military police nor the counter-intelligence investigations personnel believes that it’s anything more than a confluence of accidents.
Lieutenant William Campbell of the CSF Intelligence Division believes differently. What he doesn’t know is who or why.
And if he can’t figure it out soon, he could die with her.