No, once an earthquake has started there is nothing we can do to stop it. What we can do is make the effects less disastrous in some cases, by using the prediction methods available so that it's possible to take measures to protect ourselves when an earthquake strikes. It is possible to predict which areas are more prone to earthquakes and build structures that are more resistant - though a really powerful quake may well be too much for any man-made structure to withstand. It's also possible now to measure tremors in rocks etc and know when a quake is in its early stages.

Although we can't prevent earthquakes, human activity can sometimes cause them. There have been tremors detected in mining areas, for instance. However, such activity has never caused a major earthquake.