Significant Earthquakes and Faults
Fault Name Index
North Frontal Fault Zone of the San Bernardino Mountains
Type of Faulting: primarily thrust
Length: 65 km from end to end, but cut by the Helendale fault; the western portion is some 35 km long, and the eastern portion is about 25 km long
Nearby Communities: Apple Valley, Lucerne Valley
Most Recent Surface Rupture: Holocene, mainly; some Late Quaternary and Quaternary
Slip Rate: 1.0 mm/yr on the western segment; 0.5 mm/yr on the eastern segment
Interval Between Major Ruptures: uncertain
Probable Magnitudes: MW6.0 - 7.1 (?)
Other Notes: This fault zone dips to the south.
The North Frontal fault zone of the San Bernardino Mountains is a zone consisting of numerous fault segments. The primary sense of slip is south-dipping thrust. This zone interacts with several other faults in a variety of intersections. It seems to be offset (right-laterally) by the Helendale fault, and forms a complex junction with the Old Woman Springs fault.
Because this zone is somewhat fragmented, many of the individual fault segments have their own, commonly-used names. Among these are the Ord Mountains fault, Ocotillo Ridge fold, Sky Hi Ranch fault, and the Black Hawk Spring fault.