Southern California hasn't had a big earthquake since 1857. Here's what would happen if a mega earthquake hit California.

California is located in a hot-zone of fault lines that can rupture without warning. Parts of the San Andreas fault have not ruptured in over 200 years, meaning it's overdue for a high-magnitude earthquake commonly referred to as "The Big One." Here's what experts say could happen in seconds, hours, and days after the Big One hits the West Coast.