The recent earthquakes near Ridgecrest, California, were unusual in a couple of ways. The first, on July 4, was a 6.4 magnitude quake, while the second, a day later, was a 7.1 magnitude quake, some 11 times more powerful. The initial earthquake has thus been categorized as a pre-shock, having occurred before a stronger one though both have been followed by numerous aftershocks; the first quake was centered 6.6 miles below the surface of the desert while the second was 4 miles deeper.
Well northeast of the San Andreas Fault, these strong earthquakes developed on two perpendicular fault lines that stretch beneath the Mojave Desert at the south end of the Owens Valley. The latter runs NNW to SSE between the Sierra Batholith and the fault-block White Mountains Range of the western Great Basin; both of these ranges continue to rise and the crust of the Great Basin is under increasing tension (pulled apart in a West-East direction).
These earthquakes demonstrate the complexity of fault lines in Southern California, many of which are not completely mapped. While the earthquakes occurred far from the San Andreas Fault (which will eventually deliver "The Big One") their occurrence may reflect increasing pressure within the latter Fault and their crustal movements may trigger additional earthquakes as pressure is transferred to other fault lines that crisscross the region.
See also: The Nature of Aftershocks and Earthquakes & Tectonic Plates
Well northeast of the San Andreas Fault, these strong earthquakes developed on two perpendicular fault lines that stretch beneath the Mojave Desert at the south end of the Owens Valley. The latter runs NNW to SSE between the Sierra Batholith and the fault-block White Mountains Range of the western Great Basin; both of these ranges continue to rise and the crust of the Great Basin is under increasing tension (pulled apart in a West-East direction).
These earthquakes demonstrate the complexity of fault lines in Southern California, many of which are not completely mapped. While the earthquakes occurred far from the San Andreas Fault (which will eventually deliver "The Big One") their occurrence may reflect increasing pressure within the latter Fault and their crustal movements may trigger additional earthquakes as pressure is transferred to other fault lines that crisscross the region.
See also: The Nature of Aftershocks and Earthquakes & Tectonic Plates
