It has been a century since the infamous 1906 San Francisco earthquake and Californians live with the knowledge that it's only a matter of time before they're hit again. Los Angeles is the second most populous city in America. If an earthquake hit directly beneath downtown LA, scientists believe that tens of thousands would be killed. Just how would the city respond to a 7.5 magnitude quake? Take a look at how well the emergency responders could cope. A CGI worst-case scenario will show the incredible damage and destruction that would cripple one of the most important cities in the world.