Earthquakes fall into Chaos Theory, same as the weather. I ran my own world wide sensitive seismograph for many years and was a part of the B.C. seismography system. I could detect anything from ocean waves hitting cliffs during storms 400 klicks away to earthquakes in Greece.
Like the weather the closer in time to the event the more accurate the prediction. That is a matter of weeks at the best unless it is something like a volcano or an atomic weapon that you know is going to blow soon as well as mine blasting. In the case of the weather if one says it will be similar tomorrow as it is today one will be correct about 70% of the time.
Here on the west coast of Canada we are waiting for the BIG one. Based on previous records it is a bit overdue. The chance is stated as percentage probability of it happening sooner or later. There are some interesting correlations though. There is a higher chance of a swarm of small quakes every spring in this general area.
Being in a big one is very interesting. Many years ago I was in San Francisco staring at the remains of King Tut when a shallow 6.2 hit. The quake resistant museum building began sliding on its foundation about six inches, back and forth. It wasn't easy to stand. Hundreds of alarms began sounding. The security people were totally confused about what to do. One person ordered everyone to stand against the walls. Stupid. The walls were filled with artifact displays. If I was a criminal I could have stolen just about anything in the first minute or so. Lie down or on your knees would have been appropriate.
Another time when I was quite young a bigger one hit. I ran outside and could actually see waves passing across a large open field of short grass. It was like standing in a small boat in the ocean. I have been in about five earthquakes that caused some damage. Then there was Mount. St. Helens. I wasn't near it but it was a close call for the ash storm.