I think it's better to start from mechanical approach especially about deformation. There are two kind of deformation those are: brittle (accomodate by translation and rotation) and ductile (accomodate by dilatation/change in volume and distortion/change in shape. In this case concern may take in brittle deformation. Brittle means material acted by strees follow elastic (be able to back to original condition if yield strength do not achieve) mechanism until yield strength achieved and then failure so deformation will occurs if given force exceed material strength . When material failure, it's released energy as a shock. This kind of shock in rock mass I think that what people call earthquake.
So no matter where or when if this mechanism as explain above occurs, earthquake will happen. In geology point of view it’s occurs in : magma chamber, when magma penetrate rock wall (vulcanic earthquake), plate convergen such us subduction, collision, obduction (tectonic earthquakes) even in passive margin (unactive plate boundaries), deep water avalance (potential energy release). Energy released by forming of fracture, fault, fault/fracture propagation, elastic rebound mecanism etc.
