See it is relatively easy to predict where a large earthquake might occur, assuming you have been monitoring deformation for a long enough period, more or less equal to the average inter-seismic interval (decades-centuries).
In principle earthquakes are simple, i.e., the fault accumulates strain and then eventually slips/ruptures. The million dollar question is what triggers it, and till date there has not been a single reliable precursor.
It is like predicting failure of a wooden (e.g., balsa) stick by bending the two sides with your hands, i.e., you know it will break more or less somewhere near the center, where the strain is highest (assuming homogeneity in properties and geometry) but getting the timing right is significantly harder and very difficult to reproduce. It is even harder in case of earthquakes, given the heterogeneity, non-linearity in the system.
So with time it will get easier to predict location of large earthquakes, as we monitor strain accumulation using modern tools like GPS, InSAR etc., but getting the timing right to even within a few years will be much harder. For example, we know that Southern San Andreas is due to for an earthquake (just based on the amount of slip deficit) as the last major earthquake was in 1857. But will this earthquake occur, today, in five years or within next 50 years, is unknown. 441
Having said that additional faults in SoCal (e.g., San Jacinto and Elsinore) make the situation even more complex. Same goes for the North Anatolian fault near Istanbul, i.e., we know that an earthquake will occur there soon, as the entire plate boundary except the part near Istanbul had ruptured at least once in the last hundred years. See here for more details.
But getting the timing right for short term forecasts right now (and IMHO even in the next few decades) is impossible. Your only hope is alarms based on P-wave arrivals but then the earthquake has already started and heading towards you. Note: P waves arrive faster than surface waves, which cause most of the destruction so you might have a few seconds (depending on how far you are from the hypocenter) to take cover, automatically shutdown crucial stuff like gas flow in underground pipelines, subways, power plants etc. 87