The San Andreas fault at Cajon Pass

The San Andreas fault at Cajon Pass; this view is from one of our USGS-Caltech SoSAFz sites that I upgraded to improve low-latency GPS performance for use in the prototype earthquake early warning system. The red arrows point to the trace of the fault where it passes up Lone Pine Canyon towards Wrightwood, California in the distance. Los Angeles is behind (south, or to the left of) the San Gabriel Mountains in this photo. Click the small image below to see the full-res annotated photo.