A Chicxulub-sized event rings the planet like a bell, any fault that is near its critical strain is apt to let loose.
Doctors and coroners have a term, coup contercoup, that means damage to the opposite side of the brain from where the skull was struck.
Imagine you are standing on the spot exactly on the opposite side from the strike. The shock waves race around the globe and come together (focus, if you will) right under your feet!
On a lower gravity bodies such as the moon, big impacts have delivered sufficient coup countercoup force to jet material off into space.
I don’t doubt that nearby magma would be squirted up through the resulting shattered bedrock.
Add to that the fact that Chicxulub was a shallow water strike and the surrounding sea formed a wall around the white hot crater as it attempted to flood in. It was like a 120 mile wide rocket nozzle jetting vaporized seawater and any entrained atmosphere into space. As the crater was quenched, the force of the boiling reduced, and the remaining flood of sea water and air steam-cleaned half the planet.
It was a bad day.
On land nothing larger than a house cat survived. I suspect all the surviving animals were burrow dwellers, animals already used to breathing lower oxygen content than their larger peers. The thinned atmosphere was a final insult to the bigger surface dwellers.
To which I might add, ringing the planet like a bell and smacking the opposite side with converging shock waves would probably have much the same effect on a pocket of dissolved gas-filled magma that shaking and dropping a bottle of soda would have on the soda.
+1 for coup and knowledge of reflection /focusing of vibrations in a round object.
Larger than a house cat, not a burrow dweller
Was at the supposed ground Zero, apparently had an OK day.