Velocities computed for Station 650.01 are probably irrelevant because only the early part of the ground motion was recorded before the circuit failure at 1.436 sec (vertical dashed line in Fig. A.1), Magnitudes of the velocities included in Table 1.3 for this station may be reasonable, but it is highly probable that a very different range of velocities would have been observed had the complete acceleration-time sequence been recorded. Ground-transmitted velocity curves for Station 650.02 illustrate the effect of long-period minor changes in recorded acceleration which are probably extraneous to ground motion. All three components of velocity at this station, Figs. A.2 to A.4, include one signal of about 3.5 to 4 cps and another signal of either 0.6 or 0.3 cps. The former corresponds to the dominant frequency in the acceleration, and the latter is hardly distinguishable in those data except perhaps as a modulation in the radial and tangential curves. The full significance of these low-frequency effects cannot be appreciated from the velocity data alone, although they do evidently increase the maximum peak-to-peak amplitude of the velocity by factors cf from 1.5 to 3. The more serious effect of the anomalies will be noted in displacementdata. There are somewhat similar anomalies evident in the air-shock induced portions of the velocity curves, although here the spuriousness is not so certain; the low-frequency components may well be legitimate ground-transmitted signals comprising part of the late seismic reflection or a Rayleigh wave. However, that portion of the curve, particularly for Station 650.02, which corresponds to the high-frequency acceleration appears only as relatively minor oscillations in the velocities superimposed on much lower frequency signals of amplitudes several times those of the high-frequency component. Because the durations of the damped wave-train associated with incidence of the air shock are short and data were integrated over a correspond- ingly short period, long-period drifts have little influence on the results. However, the length of the air-shock induced accelerations included in the integration is considerably less than that of the positive phase of the air shock and may not give a complete picture of maximum velocities. Velocity curves derived for Station 650.03 (Figs. A.5 to A.7) are essentially free of serious extraneous signals. The earlier part of the curves (ground signa!s) shows no long-period large- amplitude effects. The air-shock portion of the curves includes a 1.1-cps signal, but this is compatible with reflected signal frequencies and its occurrence at about 9 sec after zero time suggests that it may be part of a reflected pulse. The data in Table 1.3 for this station are therefore all valid. Parenthetic values of amplitude represent a superimposed signal in the case of the air-shock induced ground velocities and are approximately the sum of the positive and negative peak velocities of the earlier part of the curves. Vertical and tangential velocity data from the shelter, Station 603, include a long-period oscillation which might be spurious. A similar long-period effect is not obvious in the radial velocity. The air-shock induced velocities are reasonably free of extraneous signal, although two frequencies are evident. One of about 100 cps may represent reaction of the structural elementitself and the other, about 10 cps, oscillation of the structure-foundation system. Data from Station 650.06 are of no real significance to damage or to structural response. However, these data, in particular those transmitted from Ground Zero through the earth, were used for testing integration procedures. Numerous corrections were made as noted in Appendix B, and only a short portion, including the first reflected signal, was carried through the finally corrected integration. Duration of the data integrated for the air-shock induced curve is short a0 that effects of spurious signals similar to those which altered ground-transmitted data are not noticeable. 1.5.3 Displacements Corrected velocity-time data were integrated to displacements. Iteration serves to enhance further the influence of the long-period components at the expense of the short-period signals. In the second integration this effect can result in extinction of the short-period infor- mation, making the results worthless. Unfortunately in some insiances this result was attained in processing the Operation Ivy acceleration data. Displacement-time data are included in the graphs of Appendix A asthe third curve in each figure. Data from these curves are compiled in Table 1.4. Maximum displacement values in 25