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.
“and caused the 1987 Whittier Narrows earthquake”
That’s what I suspected. I’m around five miles from the epicenter but the Whittier fault runs near my house and the quake felt very strong, really tossed my house around.