A city block? I doubt it. I mean vaporize? If that's true, then that's really cool and interesting but I would guess maybe 100 square feet. It's falling at maximum velocity at most, not the speed of light. I'm not saying "No way, you're wrong" I just find it hard to believe. If you have the facts though I would like to see them because now I'm curious how small a meteor can be to cause significant damage.
Perhaps "vaporize" is a bit dramatic, BUT... Assuming a common iron meteor, with a diameter of about 30cm (from the comic) impacting earth on dense rock (concrete, from the city) at an angle of about 60 degrees (from the comic); I get a rim-to-rim crater diameter of about 78 meters.
http://www.lpl.arizona.edu/tekton/crater_c.html
I got 22. So maybe we can agree that the damage would be more than the comic (and more than I would have thought) and less than vaporization of anything sizeable.
http://www.lpl.arizona.edu/tekton/crater_c.html