There was a M4.0 strike-slip quake on the Elsinore-Whittier fault. It was preceded by several smaller than M2 quakes (see link). Elsinore is one of the faults Penny had picked for the next 4+, so we can blame it on her. This is a long, continuous, active fault so capable of a catastrophic quake given its location.

It would be interesting to understand how the foreshocks to this one worked: what was going on down 9 km of so.

Chris

• Elsinore-Whittier M4