Hi Roger. That is the theory, but is it the correct one? What if the rock that generated the M=0.1 quake was only big enough to cause a quake of that magnitude? All of the stress was released with that quake so how could it rebuild the stress to cause a larger quake if the rock no longer exists?

It doesn’t. The fault continues to move until a larger rock is made contact with. Is it that contact that causes a larger quake? Does this continue until two rocks of equal size and strength meet and we get that really large quake that brings down a city?

Indeed it could be two very large rocks that start to give beginning with moderate quakes until finely it can no longer resist movement and lets go with one great quake. Does it always occur that way? Take Care…Don in creepy town