The Mussel Rock area is where the San Andreas fault comes out to sea on the SF Peninsula, and right at this spot there is an interesting view of 1950s ticky-tacky houses perched right along the edge. These homeowners have a great view of the Pacific ocean–for now.
The 1906 earthquake caused a huge landslide at Mussel Rock, and the debris covers the fault trace so that now it is quite obscured. In times past, conceivably, the San Andreas was brilliantly exposed in steep cliffs, such as we find just a mile north at Fort Funston, but it will take a long time for erosion to recreate such a dramatic cliffside presentation of the San Andreas.
In the meantime, we can look at the precarious position of these homes and wonder what the builders were thinking.