Late quaternary history of the Stillwater seismic gap, Nevada

Abstract Fault scarps that formed during the 1915 and 1954 earthquakes in central Nevada are roughly aligned, but are separated by a gap of 40 km. The gap contains no historical scarps and has been termed the Stillwater seismic gap. The abundance, size, and distribution of prehistorical fault scarps is similar in the Stillwater seismic gap and the 1915 and 1954 earthquake areas, and overall height and long-term uplift rates of range blocks are similar throughout the area studied; thus, the faults in the gap do not appear to be locked or appreciably more or less active on a long-term basis than those in areas of the 1915 and 1954 earthquakes. None of the scarps in the gap is likely younger than about 300 yr, so that no major earthquake occurred in that period. The Stillwater seismic gap is part of the central Nevada-eastern California seismic belt, where large-scale surface faulting events have occurred at intervals of a few years to a few decades in a pattern that suggests incremental filling of the belt. If that pattern of belt-filling continues, the Stillwater gap is a likely site for future major faulting, but the low level of seismicity in the gap area suggests that the next major earthquake there is not imminent.