Microseism measurements can assist in prediction of ground-motion amplification and microzonation. A series of array measurements were conducted in the Port Hueneme, California, area. The measurements were repeated, and the error of microseism measurements is discussed. From the seven individual trials, it was possible to show the convergence of microseism measurements and their repeatability. The series of array measurements of microseisms used both a soil and a rock reference site. The soil site was a site having a well-defined boring log. A comparison is made between results obtained using a rock and a soil reference site. It was found that qualitatively the general dimensionless shape of relative amplification contour plots was similar using both reference sites. Both reference sites showed the same regions as having higher amplification compared with other lower regions.