Here's one note on the Garlock Fault:
Slemmons said one apparent threat to Las Vegas from regional earthquakes is the Garlock fault, which branches off the San Andreas at Tejon Pass, south of Bakersfield, Calif. The Garlock extends to the south end of Death Valley and is 65 miles southwest of Las Vegas.

It is an interesting fault zone to geologists, Slemmons said, because it represents the boundary of two different blocks of rock, the Basin Range and the Mojave.

And then there's this that I think has been posted a few times now:
Scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and the University of California, Los Angeles, have concluded that earthquake fault zones in California's eastern Mojave Desert are moving in different ways than they expected.

For years researchers were aware that movement in the southern California shear zone was distributed over a 100-kilometer (60-mile) wide area. However, they assumed that deep below the surface the Blackwater Little Lake and the Garlock faults were creeping steadily, something that the new study seems to contradict.

New findings indicate that more than half of the right-lateral motion of the Eastern California Shear zone is sharply concentrated along the Blackwater Little Lake fault system. The rapid strain accumulation observed along the fault system indicates that the fault is building up stress in the shallow crust at a rate three times faster than the rate inferred from geological observations. This may be the manifestation of stress transfer between the Garlock fault and other faults in the Mojave area, in particular those that produced the magnitude 7.3 Landers earthquake in 1992 and the magnitude 7.8 Owens Valley earthquake in 1872.

Another reference said the garlock fault developed during the Pliocene-Miocene which puts it somewhere between 2 million and 23 million years old.

I'm sure it has something to do with the rift zone coming up from Baja and the Eastern Shear zone....

Canie