How could an asteroid have wiped out life on earth?

First of all asteroids that size for the most part have been destroyed through collisions so an incident like this has a low rate of occuring. But it could land in the ocean and cause a mive Tsunami. It might also hit a tectonic plate and cause violent eruptions and or earthquakes. An impact land would cause forest fire, dust storms, mive amounts of winds of impact. Also a theoritical super huricane is possible if a large enough asteroid landed in the atlantic.