Scientists can measure when there's an increased tension, but that doesn't guarantee an earthquake will follow. It can be relieved by creep or it can be released all at once. It's like sitting on the end of a tree limb. You can see it bend, you can see that your weight is adding tension to the branch, but you can't predict when or if it will break. What they are trying to do to stave off disaster is pinpoint those areas where earthquakes will most likely occur, and then prepare for them with building codes and other safety measures.
Earthquakes are most likely to occur where tectonic plates are pushing against each other.
Here, great numbers of earthquakes occur. The margins of the African plate and the Australian plate follow a similar pattern. Their edges are marked mountain belts and volcanism. We find high intensity earthquake zones along the Pyrenees, the Alps, and the Alpine Himalayan chain, as well as down into Singapore and Malaysia. These are all places where the plates are colliding.