UNLV researchers have completed the most detailed three-dimensional model to date showing how shallow sediments of the Las Vegas valley will respond during an earthquake.

The model can be used to design safer buildings and highway bridges and is the latest step toward the team's development of a comprehensive seismic hazard map for Las Vegas.

Nevada ranks third in the nation for risk of large-magnitude earthquakes. In Southern Nevada, active faults capable of producing an earthquake of magnitude 6.0 or greater have been identified.

Howard R. Hughes College of Engineering professor Barbara Luke and an interdisciplinary team of UNLV faculty and students performed site surveys throughout the Las Vegas valley over the last two years to measure profiles of shear-wave velocity.

Shear-wave velocity is a measure of the speed at which certain stresses move through the various sediments that make up the valley floor.

"The shear-wave velocity model is important because it will tell us how the different parts of the valley would react to an earthquake," Luke says. "These measurements translate into guidance on structural design requirements in the community."

By combining results of direct field testing with analysis of more than 160 seismic site classifications filed by others with local government agencies, the UNLV research team compiled a database of 230 shearwave velocity measurements.

Using the database and other sources of information, the team created the shear-wave velocity model for the valley to depths of hundreds of feet. The final product for the research team, a seismic hazard map, will be used by local officials in disaster relief planning, land use planning, and assessment of existing infrastructure in the event of an earthquake.

Luke and colleagues Aly Said, also a UNLV engineering professor, and Wanda Taylor, interim dean of the College of Sciences and a geoscience professor, were awarded a multiyear grant from the U.S. Department of Energy in part to determine which areas of the basin would be most susceptible should a major earthquake occur.

A more detailed explanation of the project appeared in the November 2008 issue of The Leading Edge, an official publication of the Society of Exploration Geophysicists. More information on the project is also available.