stand that centered on the southern third of the island. Trees in the main portion of the stand averaged 80 ft in height, with many individual specime s up to 42 in. in diameter at 5 ft abové ground. The shorter trees to wig¢ -rd of the stand center were thicker for their height and therefore stronger. Branches were thicx and short with gnarled ends. Undergrowth was quite.scanty in the stand center due to the deep shade cast by the crowns of the close-growing trees. Underbrush increased toward the beach on all sides as shading decreased. Although Pisonia as well as all other species are evergreens, there is consider-~ able leaf fall in the dry season. CASTLE fell in this period, and no doubt foliage was somewhat deficient although there was full shading in the stand center. Figure 2.3 shows the orientation of the stand on Victor with respect to the other two islands and Tare. An exterior view of the Pisonia stand on the southern third of Victor prior to Shot 1 is shown in Fig. 2.4, and Fig. 3.2 gives the interior stand appearance. Topography was uniformly flat above the beach slope, reaching a maximum elevation of only 1C ft. 2.2.3 William Island William Island, 29 ecres in area, supported a uniformly dense cover of low broadleaf brush species broken only by a small colony of palm trees on the southern tip and a 5 acre stand of large Pisonia in the center of the island. The palms averaged 40 ft tall and 13 in. in diameter, while the Pisonia averaged 50 ft in height with trees up to 24 in. diameter at breast height (d.b.h.). The Pisonia stand exterior view closely resembled the Victor Island stand shown in Fig. 2.4 although trees were not quite ac tall. An aerial view of William Island is presented in Fig. 2.5. Figure 2.3 gives the orientation of the stand components and their relation to ground zero. The interior stand appearance is shown in Fig. 3.1. 2.3 INSTRUMENTATION To assess the effects of the Uncle Island stand on shoc} overpressure, both static and dynamic, in terms of horizontal attenuation the ‘stand was instrumented at eight locations with twin ground-level static pressure gages and at two locations with single dynamic pressure gages at 3 ft elevation (see Fig. 2.2 for locations). Twin static pressure gage installations were also made in the cleared areas of Victor and William Islands, and a dynamic pressure gage, at 3 ft eleva- tion, was placed on Victor Island (see Fig. 2.3 for locations). 3.1 gives ground ranges for all pressure gages. Table Gage ingtallaticns and pressure messurements were provided by the Ballistic Research Labora~ tories (BRL), Project 1.2b,</ which also had pressure gage installations along @ radial blast line cleared of vegetation adjacent to the Uncle Island tree stand (Fig. 2.1). @/ Ground Surface Air Pressure vs Distance from High Yield Detonations, Cperation CASTLr, Project 1.2b, WY-995. 20 SECRET - RESTRICTED DATA