Median values of seismic noise in the period range of 0.3 to 1.3 sec were obtained from recordings at vaults of the Pole Mountain and WMSO arrays. Interquartile ranges were used to measure dispersions about the medians. Medians of the noise at Pole Mountain ranged from 0.91 mµ to 2.20 mµ in November 1962. The former value was obtained for a vault that was located in dense granite at the base of a massive granite outcrop; the latter value was obtained for a vault in a slab of dense granite located on a grassy plain. This indicated that topographic shielding from wind rather than density of bedrock affected noise. As a test of this idea, wind protection numbers were assigned to vaults Z1 through Z9 of the WMSO array based on comparative topographic shielding with respect to a known wind direction. Noise values increased as wind numbers decreased. Topographic protection and vault construction limited wind noise at WMSO.

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