The January 1994 Northridge, CA, earthquake (M=6.7) triggered more than 11,000 landslides over an area of ~ 10,000 km².  Most of these landslides occurred in a 1,000-km² area that includes the Santa Susana Mountains and the mountains north of the Santa Clara River valley (see map below).

Landslides in Santa Susana Mountains blocking road near I-5 interchange with State Highway 14.

Shallow, disrupted slide in very weakly cemented sediment in the Santa Susana Mountains.

Dust clouds created by earthquake-triggered landslides in Santa Susana Mountains. Dust was blown southwestward over Simi Valley where an epidemic of valley fever (coccidioidomycosis) occurred.

Main scarp of Rancho Camulos earth slide/flow (see map); slide moved from left to right in photo.  A man standing in the left center of the photo (inside the circle) shows the scale: the earthquake triggered 25-30 m of movement along this scarp.