[rustbucket]

My thoughts exactly. An impact that large would cause earthquakes all over the world as the pressure waves pass by, and the opposite side of the earth where the waves converge would be the focus.

My question yesterday to my sister, the geophysicist:

Could large impact craters like the one that may have wiped out the dinosaurs 65 million years ago cause pressure waves in the crust or mantle that could have traveled through/around the earth and converged on a spot on the opposite side of the earth, possible cracking the earth there and leading to giant lava flows or volcanos where the pressure waves converge?

She is thinking about her reply at the moment. Her PhD was in geophysics but her thesis was mostly just geology, so who knows.

[null and void]

It's a bit worse than that. Magma contains a lot of dissolved gasses (think of the pores in pumice) slapping a volume of such lava would be like slamming a can of Coke down, the Jolt* would drive the gasses out of solution and provoke an eruption anywhere the shock wave cracked the overlying rock.

*All the sugar and twice the caffeine...

[null and void]

A number of moons show shattered zones opposite of major impacts. It’s similar to a coup contrecoup brain injury