A massive explosion occurred near the Podkamennaya Tunguska River in the middle of Siberia. The explosion was probably caused by the air burst of a meteor or comet fragment at a height of about 5 to 10 kilometers. The yield of the explosion is estimated to be the equivalent of between 10-15 megatons of TNT. About 2150 square kilometers of trees were flattened by the explosion. That is the same area as a circle about 52 kilometers in diameter. Humans were lucky that time since the area it impacted was very isolated. If the air burst had occurred over a major city hundreds of thousands could have died. This fortunately is rather unlikely, since cities cover such a small area of the Earth’s surface.
I just noticed that the latitude of the site of the Tunguska event is nearly the same as the place I live. If the impact had occurred roughly 6 hours later it could have hit 20 or so kilometers from where I am right now.