When the earthquake hits and communications go down, digital technology isn't much help. Mobile phones stop working. The ground quite literally disappears beneath people's feet. Buildings crumble as if they are made of powder, bridges collapse, roads turn into gigantic craters. Fire and flooding follow. If the visuals all those high angle shots of apocalypse in modern American cities aren't enough to make us giddy, the rumbling surround sound adds to the disorienting effect. In terms of special effects, San Andreas is masterly. The CGI is seamless.