THE 1954 RAINBOW MOUNTAIN-FAIRVIEW PEAK-DIXIE VALLEY EARTHQUAKES - A TRIGGERED NORMAL FAULTING SEQUENCE

In 1954, four earthquakes of M > 6.0 occurred within a 30 km radius in a period of six months. The Rainbow Mountain-Fairview Peak-Dixie Vall ey earthquakes are among the largest to have been recorded geodeticall y in the Basin and Range province. The Fairview Peak earthquake (M = 7 .2, December 12, 1954) followed two events in the Rainbow Mountains (M = 6.2, July 6, and M = 6.5, August 24, 1954) by 6 months. Four minute s later the Dixie Valley fault ruptured (M = 6.7, December 12, 1954). The changes in static stresses caused by the events are calculated usi ng the Coulomb-Navier failure criterion and assuming uniform slip on r ectangular dislocations embedded in an elastic half-space. Coulomb str ess changes are resolved on optimally oriented faults and on each of t he faults that ruptured in the chain of events. These calculations sho w that each earthquake in the Rainbow Mountain-Fairview Peak-Dixie Val ley sequence was preceded by a static stress change that encouraged fa ilure. The magnitude of the stress increases transferred from one eart hquake to another ranged from 0.01 MPa (0.1 bar) to over 0.1 MPa (1 ba r). Stresses were reduced by up to 0.1 MPa over most of the Rainbow Mo untain-Fairview Peak area as a result of the earthquake sequence.