Question on meteorites hitting Earth....?

A large asteroid or comet impact will cause intense seismic shaking over a large area as well as blow out a crater that can be over 100 miles in diameter. It will most definitely trigger fault lines elsewhere into rupturing and generating further earthquakes. A large impact will also vaporize and melt an enormous quantity of rock and throw it up into space, from which it will fall back to Earth as a deadly shower of globules of red hot rock. The asteroid or comet itself will completely disintegrate, leaving nothing but tiny particles and chemical traces of itself world wide in debris layers created by the impact. A large impact could also trigger volcanic activity. It could hit the Earth on or near a hot spot, and trigger a super volcanic eruption that the ones that created Yellow Stone, Lake Toba in Indonesia or the Deccan Traps in India. All of these events would wipe human civilization out if they occurred today. More likely, there would be at least a few volcanoes that were otherwise quiet, but were destabilized by seismic shaking and thus triggered into erupting or collapsing much like the Hawaiian or Canary Islands have done in the past. However, that would pale in comparison to the initially mile high tsunamis a large impact in the ocean would cause. They will of course lose height as they spread out but when they get to shore they will still be taller than a sky scr and they will be moving faster than jet liners in flight. These waves will destroy everything and everyone for as much as 50 or 100 miles inland over much of the globe, and they can go much farther inland along large river valleys. This means that everyone near the coastline will have at most 8 or 10 hours to get away from the coastlines and there is no way to move a billion people or more to safety in that time when there's storms of falling rock and the very air being heated up hotter than a oven too. Hundreds of millions at least will perish just from the tsunamis, in addition to the millions more killed by the thermal pulse, shock waves and firestorms caused by the impact itself.