pe E.F.C, p.53 The inner boundary of the first abnormal audibility zone immediately beyond which the highest concentration of blast energy is most likely to occur seems _to be a regular function of the season or month of the year. As shown in fig 2h the inner boundary is farthest from the source in July and August (about 120 mi.) and nearest to the source in Jahuary and February (about 65 miles), Outer boundaries of abnormal audibility zones are musblzess easily determined; in fact Cox shows that t the acoustic energy in abnormal audibility Yones may simply decrease with distance fro from the source; the real outer boundary for each abnormal zone occurs at infinity. Some of the damage in Las Vegas during Operation Ranger on Feb 2 and 6, 1951, may have been caused by ozonosphere signals. No accurate transit-time observations were mad, so there is now no way to decide whether ozonosphere signals made any contribution to the damaging blast energy supply which struck Las Vegas. EFC p.95 Weather predictions, then RAOB soundings, and finally the 1.2 ton TNT shot fired 1/2 hour prior to the scheduled firing time of the Buster Dog Shot gave real cause fo for concern. Figures l0c,e, and f show that very little energy would be transmitted toward Beatty, and that no topesphere signal need be expected northwest and northeast from the firing site. On the other hand, focusing conditions existed toward the : south, toward the east and especially toward the souttieast. The advance shot prod- uced very strong troposphere signals at all our stations to the southeast and quite strong o,onosphere signals at both Caliente and St, George. Figure 21d shows the : be. magnitudes of the signals, where they remained on scale; the Test Director was warmed & that damage would likely occur southeast from the blast point. = Fig Oj shows some of the sound ray tracks toward the southeast. The distribution of energy bounded by rays having incidence angles between O deg amd 13 deg 32' is similar to that shown in Nig. 7a. An extremely heavy concentration of energy would therefore occur about 35 kilofeet southeast of ground zero. The dip in the V vs h curve between 8 and 18 kilofeet would produce a second, more distant focus. Its a c heavy concentration of energy wuld land very near the half-way point to Las Vegas and one bounce would send it smashing into that city. Jas hag iN bea In spite of the fact that we predicted that damage would be done on this date if the fission weapon were fired, the Test Director felt comp@lled to go ahead with the o operation since thaousands of visitors were present for Exercise Desert Rock, Unfortunately all results were as predicted. Measured signal strengths are shown in Fig. 21d. The noise was heard at all our stations except Beatty and Yoldfield, and in Prescott, Arizona. It is believed that in Las Vegas the signal strength HlED) 3¢ a t $€999 was about 5 pounds per sauare foot. ‘Sinc the other inhabited areas reported no significant damage, their signal strengths must have been somewhat less.