Fault coupling and potential for earthquakes on the creeping section of the central San Andreas Fault

What is it about?

In this study we looked at the creeping section of the San Andreas and tried to determine whether or not we could definitively exclude a locked zone anywhere on this part of the fault. Turns out we could not! Some more recent studies have come to similar conclusions. It seems that it is possible there is a small locked zone at depth on the creeping section! The size of this zone is unknown but it could be as large as a Mw 6 earthquake.

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Why is it important?

The creeping section is unusual, not because it has large earthquakes, but because it generally does not. However, there is some evidence that a large earthquake on the San Andreas could start as a smaller earthquake, possibly on the creeping section. Or, that a large earthquake on the southern San Andreas could rupture through the creeping section to the northern branch, or vice verse. These scenarios are probably unlikely to happen, but if they did it would be bad. That is why we need to study the creeping section and understand how it works both between and during large earthquakes.