Large midair explosion
FREQUENCY: 100 YEARS
Asteroids the size of a 10-story building, 30 meters (100 feet) across, are about the smallest that can cause significant damage. Typically, these asteroids explode several miles above Earth's surface in a large fireball. The great majority of them would blow apart harmlessly over the ocean or an unpopulated area.
Because these asteroids are so small, we have little hope of reliably detecting or tracking the estimated 200 million asteroids this size that cross Earth's orbit.
The pressure of the meteorite's impact on Earth's atmosphere causes it to explode with the force of a few megatons of TNT, more than 100 times the strength of the nuclear bombs used in Japan during World War II. Shock waves may damage objects on the ground. Some meteorite fragments might survive the explosion and rain down over the area.
Topic: Earth Science
Keywords: Asteroids--Collisions with Earth, Astrogeology, Astrophysics, Collisions (Astrophysics), Meteorites, Natural disasters, Near-Earth asteroids