Sorry David Carter you are incorrect. The entire crust is stressed and requires varying amounts of additional imposed stress to create failure and hence earthquakes. Look at any geological map and it is smothered in faults. Each one has created earthquakes when movement has occurred and retains that capability to an extent dependent upon numerous factors. Suffice it to say that in some areas a very slight increases in stress create minor earthquakes. In other areas far greater additional stresses are required to cause failure, thereby creating earthquakes of far greater severity.
Simplistically any area of the earth is an accident waiting to happen.
Frequency and severity of earthquakes is a function of multiple factors including the stress regime where the earthquake occurs.
Daily tide stresses were previously thought to be insufficient, recently, however, they have been found to correlate significantly with small earthquakes, just before large earthquakes occur.