Geotechnical Earthquake Engineering and Soil Dynamics IV contains 234 papers presented at the conference held from May 18-22, 2008 in Sacramento, California. This proceedings covers a broad field of topics in soil dynamics and geotechnical earthquake engineering including: engineering seismology, dynamics material properties, geophysical methods, SASW benchmarking, site response, liquefaction, ground improvement, embankment dams, tailings dams, landfills, levees, lifelines and networks, mapping and zoning, NEESR research, numerical modeling, piers and wharves, retaining structures, foundation dynamics, soil-structure interaction, stability of natural slopes, and surface fault rupture.