The focal mechanism was originally normal with N-S extension which made no sense at all. They must have fixed it and it is now mostly strike-slip, with some vertical component on the NNW-SSE east plane.

This is the area of the Santa Cruz-Catalina Ridge fault. This fault had a M5 1/2 or so strike-slip earthquake in 1981 (?). It is very likely where all the slip from the San Clemente fault goes. But, it is unclear how this fault interacts with the E-W, left lateral Malibu Coast-Santa Cruz Island fault.

A decade ago I paddled over to Blue Banks on Santa Cruz Island (with the late Kris Broderick) and there were some SE-striking slickensided surfaces (strike-slip, maybe right-lateral).

They dug part of the foundation for the house we are building on this island and my idea for keeping water failed immediately: it involved putting the footing into the bedrock, which is 2 m and less down. Despite 4 test pits, this did not get to the bedrock and the water was just bubbling up from below. My plan was dependent on the rock below being mostly impermeable.

The excavators are pretty good soil geologists: by work, not training.

Chris

Chris