Seismic Hazard: Stateline Fault System Is Major Component Of Eastern California Shear Zone

The fault passes within 40 km of the Las Vegas strip, 10 km of the town center of Pahrump, Nevada, and appears to end near the town of Amargosa Valley, Nevada (about 40 km west-southwest of the site of the proposed high-level nuclear waste repository at Yucca Mountain).

This fault has long been considered inactive and of only minor importance to the tectonic pattern of eastern California and southwestern Nevada, whereas fault systems like the Death Valley, Panamint Valley, and Owens Valley have received much more attention.

New research focused on the Stateline fault system is beginning to change how we view this fault zone. Guest et al. present geologic data that establishes the minimum offset on the southern segment of the fault system to be 30 ± 4 km over the last 13 million years.

This implies a minimum average slip rate for the southern segment of the fault system of 2.3 ± 0.35 mm/yr. This is twice the slip rate estimated from geodetic monitoring in the region, and therefore the fault is either in a transient period of slow slip or has been abandoned as activity in the eastern California shear zone has migrated west.

The magnitude of accumulated offset, evidence for Late Quaternary slip, and rapid long-term slip rate indicate that the Stateline fault system is a major component of the Eastern California shear zone. Given its proximity to population centers and important infrastructure in southern Nevada, the fault warrants close scrutiny in seismic hazards analyses of the region.