I suppose you're aware then, that the meteor that exploded over Chelyabinsk in 2013 was only ~20m across then.
a 4km meteor - were it to strike - would be an extinction level event.
The Barringer meteor crater was created by a 30-50m meteor
https://www.lpi.usra.edu/science/kring/epo_web/impact_cratering/enviropages/Barringer/barringerstartpage.html
Look around - you're very, very wrong here.