Chapter 2 Procedures and Test Results 2.1 PROCEDURES ~- Test procedures for Dog and Easy shots of Operation Greenhouse were carried out as directed in Appendix A. An array of stakes was located and surveyed before and after each shot by Holmes and Narver (HEN). The description of the method, together with the detailed results, are contained in Appendix B for these two shots. On George shot no formal data were taken, but some estimate of the crater was obtained from a topographic survey made of Eberiru more than a year after the shot. No precise vertical control is available from this com- parison, but it appears reliable that the origi- nal island had been leveled flat at an elevation about 10 + 1 ft above mean sea level. The present ground configuration does not represent the crater accurately because sea water soon filled the George crater through a breach on the lagoon side, and this water flowed in and out of “Lake George” with the normal rise and fall of the tide; both erosion and deposition occurred. Subsequently, parts of the area were bulldozed to isolate the highly radioactive lake in the crater from the lagoon. The survey for Mike was accomplished by H&N, using standard survey procedures and soundings; this was done about 2 weeksafter shot day. 2.2 RESULTS The results for Dog and Easy shots are presented as contour mapsin Figs. 2.1 and 2.2, respectively. Owing to a scarcity of points, the contour lines are not accurate in detail, but merely indicate the general shape of the crater. TheEasy crater is relatively uniform. The Dog crater is bowl-shaped and contains several mounds. The contour maps were pre- pared from the data in Appendix B by subtracting the final elevation from the initial elevation at each stake; hence the contour maps represent the change in depth rather than the craters as they presently exist. Figure 2.3 is the contour map of the present George crater as prepared by H&N, Assuming that the original island was flat and 10 ft above high tide and that no shifting occurred, the con- tour map is a representation of the change in depth of the crater. Figure 2.4 is a contour map prepared by A. L. Embry of J-Division, LASL, from the data obtained from the survey made by H&N. Because of the large size of the Mike crater, the original differences in surface contours are less important to the problem than in the case of the Greenhouse shots. It is pertinent to the results to point out some observations made by the author, which were reported as part of the damage survey on Mike shot.! Tis survey was made about 48 hr after shot time, and numerous pockets of turbid water were observed in the lagoon and ocean at some distances from the main crater and isolated from it by clear water. If this turbid water was dueto diffusion from the crater itself, by 48 hr one would expect enough diffusion so that no clear demarkation would exist between the clear and turbid water. On the other hand, this was not the case, and the turbid regions were well separated from the