Why was an asteroid with only a 10-15 km (7-8 mile) width able to wipe out the dinosaurs and cause the extinction of 75% of all species on Earth?

Question

That width is less than the distance I drive from my house to the grocery store. Why was that size of an asteroid able to cause such catastrophic damage?

In: 21

Answer 1

There have been a lot of studies done in the past few years concluding that this was not the only big impact around that time period; that there were other meteor/asteroid impacts of similar or even bigger size within a short time frame around that one.