Say it was the size of Corsica and traveling at the speed of a reversing truck and bumped into a land mass. Would it still be an extinction level event?
Let’s suppose some fun-loving aliens lower that rock slow enough that touchdown isn’t some cataclysmic event. We now have an asteroid 60 Km across at its widest point sitting on the Earth’s surface. That surface will immediately start to experience the pressure you’d find 60 Km deep in the Earth. There are places on Earth where the solid crust extends lower than that, there are others where that’s inside the mantle.
The weight might crush the crustal plate into the mantle, in which case the effect will be very much like a supervolcano going off. Smoke, toxic gas, exploding rocks tossed hundreds of kilometres. It’ll last decades or possibly centuries. Chances are, you’ve enjoyed your last hot fudge sundae.
But maybe the crust is strong enough to support the weight - until a few hours pass and it starts to melt from pressure and heat. As it melts it compresses, sending stress through neighbouring seismic fault lines and causing earthquakes, regular-size volcanic eruptions and tsunamis across a vast area. It may not be enough to destroy the environment, but it’ll be serious enough make everyone forget about global warming as an issue.
zxqwas@lemmy.world 52 minutes ago
Pick up a tiny asteroid and drop it from 1m. It hit the ground slightly faster than a reversing truck.
Pick up a bigger one and drop it from orbit it’s going to go faster.
Whatever you drop won’t be an asteroid because it’s already on earth.
So if you pick up corsica and drop it on florida from less than a meter up (they had it coming) there would be a mass extinction in florida. Everything under corsica would die, buried under a mass of rock, mud and whatever. If it did not die already because it could not squeeze into the less than a meter gap between the masses. There would also be an earthquake, maybe a tsunami if some of it fell in the ocean.