Late Quaternary activity along the Lone Pine fault, eastern California
The Lone Pine fault is a north-trending secondary break of the Owens Valley fault zone, 1.4 km west of Lone Pine, California. This fault forms an east-facing scarp as much as 6.5 m high across an abandoned outwash fan of the Tioga (latest Pleistocene) glaciation. The fault experienced large right-lateral and smaller vertical displacement during the 1872 Owens Valley earthquake. Knowledge of the character and amount of slip at this site in and before 1872 is necessary for evaluations of earthquake hazard near Owens Valley and may help us to understand earthquakes along other parts of the eastern front of the Sierra Nevada and in the Great Basin. Scarp profiles indicate a 1- to 2-m component of dip slip in 1872; thus three 1872-type earthquakes could have created the scarp. This number of events is also indicated by desert-varnish patterns on boulders in the fault scarp, by scarp morphology, and by sediments near the fault. Horizontal offset of a relict channel on the fan is 12 to 18 m (3 earthquakes). Horizontal offset of a younger debris flow is 10 to 12 m (apparently 2 earthquakes). Average horizontal offset for each earthquake, including that of 1872, is 4 to 6 m. The age of the fan surface is bracketed by a 21 ka shoreline of former Lake Owens and by the time of abandonment of the fan, about 10 ka. An average recurrence interval for 3 earthquakes is 5,000 to 10,500 yr. The average recurrence interval, combined with the average oblique offset for each event of 4.3 to 6.3 m, gives an average late Quaternary slip rate of 0.4 to 1.3 mm/yr for the Lone Pine fault. If we add the average horizontal-slip component for the Lone Pine fault to the 1872 horizontal slip reported for the adjacent main Owens Valley trace of 2.7 to 4.9 m, the combined 1872 horizontal-slip component for the Owens Valley fault zone is approximately between 7 and 11 m, a large value. The associated horizontal-slip rate for the Owens Vallev fault zone is 0.7 to 2.2 mm/yr.