Abstract
The June 29, 1992, Little Skull Mountain earthquake (M=5.6) was recorded at nine strong-motion stations in Las Vegas, Nevada. Ground motion on alluvial sites is much greater than on rock sites, especially at low frequencies, and had a longer duration than expected. Five of the seven stations on sediment have Fourier spectral amplifications that average at least a factor of five greater than the rock reference sites from 0.5 to 2 Hz. Thus, large earthquakes at moderate distances, that would excite strong long-period waves, are a concern. We generated synthetic seismograms, including the site amplification, for magnitude 7.4 earthquakes on the Death Valley fault system 150km from Las Vegas. The synthetics have average peak accelerations ranging from 0.058 to 0.13g at the rock and from 0.051 to 0.22g at the sediment sites. The average peak velocity and displacement is 49 cm/sec and 33 cm, respectively, on the larger component of a sediment site.
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