Hello. Also, as I understand it it takes about a 5.0 magnitude to cause a measureable amount of slip on the San Andreas and Hayward faults. If there is a 5.0 that causes a few milimeters of slip on a fault that has a 1000 milimeters/1 meter(potential 6.5> magnitude)or more of built-up strain, than the 5.0 earthquake can be a sign that the fault is about ready to begin breaking into a larger rupture. If I locate a good link on this I'll try posting it.