"I'm an inherent optimist," says earthquake expert Lucy Jones. Sitting in her bright, tidy office at Caltech, the world-renowned seismologist does not betray a shred of irony at this admission, despite how surprising it may seem coming from a woman who asserts in no uncertain terms that Southern California is headed for a devastating magnitude 7.5 to 8.2 earthquake – it's only a matter of time, she says.