An earthquake prediction is a prediction

Prediction

A prediction or forecast is a statement about the way things will happen in the future, often but not always based on experience or knowledge...

 that an earthquake

Earthquake

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

 of a specific magnitude

Moment magnitude scale

The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

 will occur in a particular place at a particular time (or ranges thereof). Despite considerable research efforts by seismologists, scientifically reproducible predictions cannot yet be made to a specific day or month. However, for well-understood faults the probability that a segment may rupture during the next few decades can be estimated.

Scientists still do not know many of the details of the physical processes involved in earthquakes and how to predict them.