parentheses are curve maxima and represent in some casesthe effect, wholly or in part, of uncorrected spurious instrument or circuit drifts. Displacements not enclosed parenthetically are either maxima or peak-to-peak values which are directly attributable to the measured acceleration. These are not necessarily true maxima because the integration process tends to submerge short-period peaks in long-period oscillations. No useful information concerning displacement can be derived at Station 650.01. No signifi- cant maximum or residual values occur in the data prior to failure indicated by the carrier monitor record. Information contained in the vertical displacement curve for Station 650.02 appears to be worthless because the 0.3-cps component noted in the velocity data obscures the 3.4-cps data in the curve. The 9-in. negative displacement is probably excessive, and no safe estimate can be made. Radial and tangential displacements at Station 650.02 are less seriously affected by spurious long-period signals. However, validity of the 3.2-in. maximum radial and 2,9-in. maximum tangential displacements is uncertain, and the 1.2- and 0.5-in. peak-to-peak displacements are probably morereliable information. Displacements associated with the 20- to 40-cps acceleration produced by incident air shock are negligible and only barely perceptible as an inflection of the curve resulting from longerperiod ground-transmitted effects. The existence or importance of false displacements in the ground-transmitted data for Station 650.03 is not so definite as at Station 650.02. However, the positive pulse of 1.5 sec duration in the vertical and radial displacement curves may be the result of false data. Peak-topeak amplitudes of the higher frequency signals, or the first inflection representing the integrated first half-cycle of the velocity curve, indicate displacements which are certainly not greater than maximum and may be low. Tangential displacements also include a long-period component, but maxima and peak-to-peak values of higher frequency componentsof this curve differ very little. Air-shock induced displacements for all components at Station 650.03 are of very similar shape. There is a negative displacement peak of 1.5 to 2.0 in. between 8.9 and 9.0 sec. Noneof the curves show the influenceof the damped 20- to 80-cps sinusoidal pulse which is so strong in the acceleration curve. Motion of the shelter, Station 603, shows a long-period displacement dominatingall three components of the ground-transmitted effect but reaching a peak at successively later times for vertical, radial, and tangential data. The displacements are large, possibly too large to be realistic, but they suggest a long-period surface wave in which displacementfollows a sequence — down, up and out, in and counterclockwise—— which is reminiscent of the hydrodynamic wave recognized by Leet after the Trinity test.’ Lack of coincidence of these large displacements indicates that they are probably not instrumental error, although the amplitudes are large. At this station there is evidence, especially in the radial and tangential displacement, of motion from an independent source at a frequency of about 1.6 cps corresponding to the higher frequency components of the ground-transmitted signal at Stations 650.02 and 650.03. Air-shock induced displacements from high-frequency accelerations at Station 603 are again negligible, but displacements of the order of tenths of an inch vertically and hundredths of an inch radially and tangentially at 1 cps are evident and do not appear to be spurious. Finally, the integrated data from the vertical accelerometer at Station 650.06 on Parry indicate peak-to-peak ground-transmitted displacements at 1.5 eps of about 0.13 in, superimposed upon a 6-sec cyclical variation. Air-shock induced displacements are of the orderof 0.001 in. 1.6 DISCUSSION OF RESULTS Ground- motion measurements of Project 6.5 show unfortunate gaps. Data from the stations nearest to and most remote from Ground ‘Zero are not useful, data from Station 603 are anomalous because instruments were mounted on a structure as an expediency following failure of 27