http://latimesblogs.latimes.com/lanow/2012/06/earthquake-disneyland-near-whittier-fault.html

The 4.0 earthquake that rattled the Disneyland Resort¹s red-carpet premiere of the new Cars Land attraction occurred near a major fault in Southern California that can produce a magnitude-7.0 temblor.

The 8:17 p.m. shaker occurred very near a section of the Whittier fault, which straddles the border of Los Angeles and Orange counties along the suburbs of Whittier, La Habra Heights, Hacienda Heights, Rowland Heights, Brea and Yorba Linda. Wednesday evening's quake occurred just 8 miles from Disneyland.

"The Whittier fault is capable of producing a magnitude-7 earthquake, so is of concern to many seismologists, as it lies directly under a large population center," according a report posted on the Southern California Seismic Network.