Pardon me for posting (Yet again), but I was wondering…Are there any estimates as to the explosive yield of the Asteroid believed to have killed the dinosaurs off? In megatons, preferably? As I remember, the crater at the Yucatan peninsula is about a hundred miles in diameter, if that’s any help.
That seems rather high to me, given that this page lists the largest impact of a Shoemaker-Levy comet fragment with Jupiter at an estimated 6 million megatons. That impact produced a fireball that rose 3000 kilometers above Jupiter’s cloudtops. An impact roughly 17 times greater than that? It should have shattered the Earth into fine grit.
I think this page’s estimates are a bit closer to the mark. They state that an object with a diameter of 1700 meters should impact with a force of about 100,000-1 million megatons. “[L]and impact raises dust with global implication; destroys area size of large state (California, France)”. Sounds close to right.
Except, the impactor which created the Chicxulub crater is believed to have been about 10 kilometers in diameter. Also note that the table which shows the 1700-meter impactor indicates such impacts occur every 250,000 years or so, whereas ones the size of the Chicxulub impactor are thought to strike every 100 million years or so - such impacts are rather beyond the scope of those appearing on the chart.
At any rate, here are some cites for the 100-million megaton figure:
Note the progression in the table on the website you linked to, Max: if you (roughly) double the size of the impactor, the yield (in megatons) increases by a factor of 10. A 10km-diameter asteroid would be roughly 5x the size of the 1700 meter one at the top of the chart. Even a conservative 4x would mean two doublings, which would result in 100x the yield of the 1700-meter asteroid - or, 10,000,000 to 100,000,000 megatons.
The size of the area destroyed was probably much larger than France (note that the area destroyed will be much larger than the size of the actual impact crater) - 70% to 80% of all life on earth was wiped out as a result.
This handy Asteroid impact calculator will let you examine the effects of asteroid speed, size and composition on explosive yield, crater size, and crater depth.
A 12 km diameter rocky asteroid travelling at 20 km/s results in an explosion of ~100 million megatons, and a crater about 150 km in diameter. A chunk of iron with the same size and speed gives ~340 million megatons and a crater diameter of 216 km.