Larry W. Anderson

The Sugarloaf fault is a slightly arcuate, northwest-southeast trending fault located near the junction of Mesquite Wash and Sycamore Creek. The fault was identified by Fugro (1981), which considered the fault in itsMCE analysis for Stewart Mountain Dam because of the evidence for possible Quaternary activity along the structure.

Horseshoe and Bartlett Dams are located In the Transition Zone of central Arizona. Within this province, faults with evidence of Quaternary activity are widely scattered, and selsmiclty Is low In comparison to other parts of the western United States.

Have earthquakes strong enough to rupture the ground surface occurred on faults in central Arizona during the recent geologic past? Could such earthquakes happen in the future? If so, where are they most likely to occur? The Seismotectonics and Geophysics Section of the U.S. Bureau of Reclamation has, during the last 6 years, been working on answering these questions