What if Asteroid Apophis Hit USA
Asteroid Apophis is a rock asteroid the size of a football field. If it were to impact the Earth is would be like 125,000 Hiroshima sized bombs. It would cause an earthquake magnitude of 6.8 on the Richter scale as the impact crater would be 3.4 miles across and 03 miles deep. The impact fireball would be 1.2X larger then the sun and would cause 25 miles per hour winds.
Viewed from San Diego, the fireball of hot vapor from the impact appears slightly larger than the sun. The heat is enough to warm, but not burn, your 
skin. The earthquake tremors wake many people from their sleep, and nearly everyone in the city notices them. Windows break; unstable objects topple over. A fine dusting of debris falls, with occasional quarter-inch fragments of rock. The air blast noise, as loud as heavy traffic, and 25 mph winds are the final signs of the impact. If Apophis were to land not in L.A. but in the Pacific, San Diego could suffer more; some scientists believe the ocean impact would trigger a tsunami.
Astrophysicists think that Apophis is the common type of asteroid, make of rock. But what if it were the rare sort, made of iron, and it inexplicable changed course and hit the city of Angels? Iron is more than twice as dense as the densest rock, and the impact would be much more devastating.