With an average of four mini-earthquakes per day, Southern California's San Jacinto fault constantly adjusts to make it a less likely candidate for a major earthquake than its quiet neighbor to the east, the Southern San Andreas fault, according to an article in the journal Nature Geoscience.
These sections are always fascinating. What makes a fault section less 'crunchy', and more of a slow grind. It could be rock type, but I think it has something to do with water. At this section the rock does not have a large difference between static and dynamic friction. It is the equivalent of grinding two bone-dry bricks against each other. However, I can't believe that water is totally out of the picture here, so I think this section will surprise us one day.