Scientists have tried lots of different ways of predicting earthquakes, but none have been successful. They haven't been able to find a signal for earthquakes( there is no obvious sign to say that an earthquake is coming very soon). They do have a pretty good idea of where an earthquake is most likely to hit, but they still can't predict exactly when it will happen.
However, the probability of a future earthquake can be calculated, based on scientific data. Scientists estimate that the probability of a major earthquake occurring in the San Francisco Bay area over the next 30 years is 67%.