At the meeting of the American Geophysical Union in December, Stanford scientists presented evidence that geophysical forces are creating new faults in the Mojave Desert. Their magnitudes ranged from 5.4 to 7.4. Faulting at Hector Mine, which is near Twentynine Palms, Calif., occurred entirely within the U.S. Marine Corps Air Ground Combat Center. While most Mojave faults traverse similarly sparsely populated areas, at least six major faults cross California's well-traveled Interstate 40. The new faults cut across old ones that have rotated into orientations that make slippage difficult.
Quakes happen when faults slip.
In a single earthquake, more than one fault may rupture, but the ruptures may not manifest themselves along a straight line. Professor Amos Nur have developed a simple model that invokes fault-block rotation to explain nonlinear rupture patterns after a single earthquake. The model may explain the behavior of Mojave earthquakes in the past few million years. The Stanford geophysicists employ Coulomb friction theory to predict the orientation of faults that form in the Earth's crust in response to stress. The orientation of a fault depends on the material properties and the relative magnitude of stress.