Explosion at Tunguska, central Siberia,
Russia, in June 1908 which devastated around
6,500 sq km/2,500 sq mi of forest. It is
thought to have been caused by either a
cometary nucleus or a fragment of Encke's
comet. The magnitude of the explosion was
equivalent to an atom bomb and produced a
colossal shock wave; a bright falling object
was seen 600 km/375 mi away and was heard up
to 1,000 km/625 mi away. An expedition to the
site was made in 1927. The central area of
devastation was occupied by trees that were
erect but stripped of their branches. Further
out, to a radius of 20 km/12 mi, trees were
flattened and laid out radially.