The signal-to-noise ratio improvement obtained with delay-and-sum (DS) processing is discussed for short-period seismic data. It is shown that at least 3 km spacing should be maintained between seismometers at the Large Aperture Seismic Array (LASA) or at another site with a similar noise environment. It is shown that noise coherency measurements are of use in determining the sensor spacing at a new array location. The parameters required for a site survey coherency measurement, such as length of data and resolution, are also presented. The design of subarrays of approximately 20 km aperture is described and array patterns are given.