Looks like it was pretty shallow, probably why it felt so strong where I am, less than five miles from the epicenter. I have experienced every Southern California quake since Sylmar, and I can’t remember one that shook as violently as this one did.
Updated at 9:56 p.m.PDT:
Preliminary data suggests Friday night’s earthquake occurred on the Puente Hills thrust fault, which stretches from the San Gabriel Valley to downtown Los Angeles and caused the 1987 Whittier Narrows earthquake.
Friday night’s 5.1 earthquake hit only about 2 to 3 miles underneath the surface, which means the shaking is very concentrated in a small area, officials said.