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D
ifferent kinds of NEAs can produce different kinds of damage. The
kind of damage depends first on the size and speed of the asteroid.
However, it also depends on where the asteroid hits. An asteroid that
hits the ocean will have a very different effect than one that strikes the land.
An asteroid that hits the water would produce the most destruction. While
an asteroid hitting land would cause damage in only one place, an ocean strike
would cause a tsunami (a giant wave). This could severely damage or destroy
cities close to the ocean over a very large area. Seventy percent of the Earth is
covered by oceans, so an ocean impact is more likely. If a large asteroid struck
the middle of the Atlantic Ocean, the tsunami could destroy cities on the east
coast of North and South America, as well as western cities of Europe and Africa.
Such an asteroid would only have to be about forty to sixty meters wide.
An asteroid strike on land would be destructive in a concentrated way. It
would take an object of about seventy-five meters wide to destroy a city. This
would not include all parts of the city, and suburbs might not be damaged so
severely. To destroy an entire urban area would
take an asteroid of around 160 meters. A 700
meter asteroid could destroy a small country.
However, a one or two kilometer asteroid strike
would be deadly enough to kill millions of
people, simply by the dust and vapor it would
throw into the atmosphere.
