Operation Long Shot - Ground Water Shock Measurements

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BEST AVAILABLE COPY objectives oi this project were he ground notions in the region of effectiveness of containment (1) ■ to measure and above the detonation, and (2) to obtain ground-induced water shock measurements at close-in shoreline i stations for possible correlation with injury to marine wildlife. There were three distinct groups of instrumentation: (1) downhole accelerometers and particle velocity gages, (2) sur face velocity gages, and (3) water station gages. The recording nometer oscillographs and F.M magnetic tape recorders, Measurements were obtained from essentially all stations. Time of arrival information yielded a primary wave propagation of approximately 11,100 fps. Both the acceleration and velocity c...., indicated decidedly stronger motions than were predicted by previo data obtained from underground, contained shots, although rates of attenuation were near those predicted. Peak transient pressurechanges of approximately 20 and 7 psi were measured offshore at slant ranges of 9,340 and 27,320 feet, respectively. it was concluded that the weapon was successfully contained despite a surface zero peak transient displacement of 7.3 ft and that the ground-induced water pressure at the close-in shoreline ^station was insufficient to injure marine wildlife. BEST AVAILABLE COPY

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BEST AVAILABLE COPY Ttiis report describes an experiment conducted by the connection with the Project LONG SHOT detonation, a part of the Vela Uniform Program which is directed by the Advanced Research project Ag ency (ARPA). The study reported herein was funded by the Defense Atomic Support Agency (DASA). I The work was conducted by personnel of the Nuclear Weapons Division Chief, and Mr. L. F. Ingram, Chief, Physical Sciences Branch. Project personnel was J. D. Day, Chief, Blast and Shod assisted with the instrumentation and data recording. Col J. h. Technical Director during this work. The authors gratefully acknowledge the assistance rendered by the WES Concrete Division personnel who supervised the instrv ment hole grouting, and Mr. Ralph Bendinelli who was the author of Appendix A of this report. BEST AVAILABLE COPY

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BEST AVAILABLE COPY Theory and Predictions 2.2.1 Gage Location and Layout ............................................ 2.2.2 Transducers and Calibrations .................................

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BEST AVAILABLE COPY Predicted radial acceleration, versus slant range Predicted radial particle velocity versus slant Downhole gage layout ...................................................................... 2.4 Typical water st at i on array ............................................ 3.1 Mot ion histories in Tp-r sjuIV3.4 Early n lOtion histories in ErI-5................................. 3.7 olx on histories in EH- 5................................................. o o 3.3 lloz ion hist orie s in EH- 5................................................. 3.10 Action Histories in EH- 5................................................. Ci . 13 Motion historie s in EH-5................................................. 3.15 Motion histones in 3.16 Motion histories in T’C* OJ-A* A.J 4 4 4 4 ... 4 4 4 3. IS Motion histories in 3.19 Mot ion histories in EH-1................................................. 3.22 Motion histories on surface ............................................ 3.23 Motion histories on surface ............................................ 3.24 Motion histories on surface ............................................ 3.25 Motion histories on surface ............................................ 3.27 Motion histories on surface ............................................ 3.23 Pressur e history at Cyril Cove ....... 3.29 Motion histories at Cyril Cove ................................. 3.33 Vertical acceleration versus si range BEST AVAILABLE COPY

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3.34 Vertical downhole particle velocity versus slant 3.35 Vertical surface particle velocity versus slant BEST AVAILABLE COPY

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BEST AVAILABLE COPY The primary objectives of this project wore: (1) to measure and analyze ground motions in the region above the detonation in light of effectiveness of containment and (2) to obtain groundinduced water shock measurements at close-in shoreline st at ions for possible correlation with injury to marine wildlife. A secondary objective was to compare and utilize (for protective .'structures purposes) the results of the ground motions with those PILE DRIVER, SALMON and others. Project LONG SLOT, a part of the by the ARPA, studied detection and ice underground nuclear bursts. The LONG 80 NT nuclear burst detonated 2,300 ft Amchitka Island in the Aleutian chain, seismic measurements were made by otho Tne depth oi ourial was selected theless, earth motion measurements wer the detonation and near the surface to Vera Uniform Program Girec.*-* ratification techniques for SHOT test consisted of an below ground surface or. r laboratories and agencies, to avoid venting; nevere needed in the region abort.- assess the effectiveness of BEST AVAILABLE COPY

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BEST AVAILABLE COPY the containment. In addition, ground-induced water shock for documentation ox possible biological danlage to marine wildlife. 1.3 THEORY AKD PREDICTIONS Free field radial peak particle accelerations and peak particle velocities were determined from the composite curves of these parameters which are found in Nuclear Geoplosics, DASAMay 1SS4. These composite curves contain data obtained in salt, granite, ■cuff, and alluvium, scaled to 1 XT. For Operation LONG n..oI, tne granite caca were useo, scaled to SO XT. One ocner adjustment was made to convert from granite to andesite (the primary geological formation of Amchitka Island). This conversion was made oy considering uhe pea.< particle velocity (v) to ie proportional to seismic velocity and pean parcicle acceleracio.'. (.*y proportional to the square of the seismic velocity. The following for anaasi te: v ~ c Using the granite data points from Nuclear Geoplosics, the adjusted values for andesite were computed as follows: BEST AVAILABLE COPY

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BEST AVAILABLE COPY poan acceleration in andesite peak acceleration in granite seismic wave velocity in andesite seismic wave velocity in granite peak particle velocity in andesite peak particle velocity in granite These data are plotted versus slant range in Figures 1.1 and 1.2. Table 1.1 lists the predicted peak values oi the various oi the underground tests at the Nevada Test Site, in particular double the free field values. The water pressure predictions wore estimated as iollows; Values for stress versus distance for nuclear explosions in granite BEST AVAILABLE COPY

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PEAK PARTICLE ACC EL ERAT IO N BEST AVAILABLE COPY BEST AVAILABLE COPY

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BEST AVAILABLE COPY Figure 1.2 Predicted radial particle velocity BEST AVAILABLE COPY

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BEST AVAILABLE COPY by the following equation: C. = incident stress in rock, psi Subscript (1) refers to rock and (2) refers to water These values are listed also in Table 1,1, BEST AVAILABLE COPY

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BEST AVAILABLE COPY This project was executed in two phases. Phase I consisted of the placement of the downhole or exploratory hole (2K) instru mentation in June 1S35. Gages and supporting equipment, along with project personnel, were flown in to Amchitka on this early vicinity of the device emplacement hole could be completed. The emplacement hole effort was on the critical path and had to be Progect personnel then denar^ee lor tne nome station *.0 finisn preparation for Pnase ix, the iinax ana tiost important tasx. Phase II began during mid-August with equipment and personnel departing for the test site once more. Site activi ties consisted of surface and water station emplacements, along with instrumentation trailer check-out. Gages and recording equipment were given final calibrations and check-outs and the entire electronic system was wired for remote operation from the Control Point. BEST AVAILABLE COPY

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BEST AVAILABLE COPY 2.2.1 Gage Location and Layout .■ There were three were "tiLie exploratory iioie gages. Tne so were grouted in holes EM-5, EH-3, and.EH-1; shown in Figure 2,1. These gages were encapsulated in. specially-designed, hermetically sealed, steel canisters (Tigure 2.2). The six canisters for EM-5 contained a vertical particle velocity gage and a vertical accelerometer along with line-matching transformers and calibration relays. The three canisters each in EH-3 and SII-1 contained only vertical particle velocity gages with transformers and relays. The next group of gages were the surface velocity gages. This group consisted of seven particle velocity gages which were.mounted at the surface on steel channel beams which had been grourec into me sunace roch, througn tne musnog. The surface array is shown in the over-all layout in Figure 2.3. The final group of instruments consisted of the water scat ion gages jure 2,4) . Tne re were tnree suen s^, an ions one located in Cyril Cove, one in Xirilof Bay, and the third in Constantine Harbor. Since all scarions wore alike, only one description will be given. The srarion consisted of a 3,5GC-lb concrete anchor block sunk in approximately 60 ft oi ;e support cable suspended above it. From BEST AVAILABLE COPY

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BEST AVAILABLE COPY Note: Canister was filled with epoxy potting material to waterproof and damp would bo oscillations. Figure 2.2 Gage canister BEST AVAILABLE COPY

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BEST AVAILABLE COPY WATENSURFACE MARKER BUOY CABLE ^— VELOCITY GAGE BEST AVAILABLE COPY

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gages w ere viscousiy c aiftp 0 cl w 11 a ol the predicted range to a final value of 140 percent. A cal in >: her to relate a known electrical pulse to the physical principle. Tne gages enploy a variaoie reluctance picu—up to was by Sk”.gage assign 1 e itoae 1 usee on

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BEST AVAILABLE COPY when measuring* horizontal motions. o and \* soa smax 1 so r i ng x, o no mic nmoGa natixr ax ^r0qagncy o support the pendulum when usin relationships are given for the high and which tne response xs clown o percent j ax me tC0/0r (low frequency), where axis the driving frequency, and n the frequency response is essentially flat between O.G^ zontally, an external magnet is usee to pul^ tne penouxun up ( to 2 g?s is imposed on the pendulum by ^he spring iorce ana tne damnin'7, iluxc a re core ox tne motion is mn micnortion o: wnicn is The slope of the recorded trace represents a BEST AVAILABLE COPY

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Engineering Company llodel P2‘1A. This gaye has a a lush stainless steel diaphragm which moves a small mass whose motion is sensed by a variable reluctance pick-up. The gage pressure ranges were 0-200 to C-5G0 psi. The natural frequencies ranged from 30 to 35 kcps. These gages were calibrated in the laboratory using compressed gas as a pressure source. An electrical-calibration was perrormea in conjunction with tne physical tes'e. borrowed from the Xaval Ordnance Laboratory, Silver Spring, performed on this gage in the laboratory. 2.2.3 Installation. As was previously mentioned, the downhole gages were mounted inside steel canisters. These canisters were then fastened to each other at the proper spacings using swivels and wire rope. Instruments were protecte passed through the top of the canisters by means of a pressuretight fitting and externally protected by means of a plastic con

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BEST AVAILABLE COPY /as connected ao cne cram ana preceaec "cnc density aatchiug grouc was pumped into the hole io affix the joined co the surface rock. on each scat ion. opoci any” ao signed ms i r ume me cames i r o m m-. co n c re ^ e an c no r £j p j. a ce c i n sme ion a panicle velocity rage was oo^tea to cne i*. 2.2.1 Re cordir.:; I ns t rumen t at ion. The s ignal cone i t i onin^ BEST AVAILABLE COPY

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BEST AVAILABLE COPY paax pYassuYGS in exa a vox d ox x a x x uy’g ox cxg a^acxYOixxc sysic BEST AVAILABLE COPY

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BEST AVAILABLE COPY zero me a s 11 r e me atso ^ 0 0L.AA JCt. Xag velocity a*'*ci vcA-*ter ootainea iron tae Cyrx^ Cove arc BEST AVAILABLE COPY

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BEST AVAILABLE COPY ter co nve r sian .Cd p ore process GU Lectroe core u. e e i' 3 ,o2 no a o ii ^ rwen

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BEST AVAILABLE COPY o 3.^. Mot ion h i.r.l.oi’i os in AVAILABLE COPY depth 0 it and slant ran^e 23W0 ft

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BEST AVAILABLE COPY 7 I'.M'i ion ^to)'Los in BEST AVAILABLE COPY 'plh 500 i’t and slant v

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ARR IV ALT IM E,M SE C BEST AVAILABLE COPY Figure 3.32 Arrival time versus slant range BEST AVAILABLE COPY

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BEST AVAILABLE COPY obtained during the exploratory drilling was 11,000 ft/sec for the breccia in the shot area. This value had been used in adjusting the jgranite data for making predictions. A high velocity (13,200 ft/sec) was computed for the Constantine Harbor station. This value approximates the value listed for the main andesite at shot depth (14,000 ft/sec). This would indicate that the andesitic outcroppings noted at the harbor are probably connected with the andesite at the shot point. Moreover, the average propagation velocity should be larger at this distance than for the closer-in stations because the travel path is through a larger fraction of higher velocity material (the deeper strata). Although peak motions were recorded, all downhole gages in EH-5 failed at various times after onsst of motion. The failures w'ere probably caused by cable breaks, and are indicated on the data plots. Figures 3.5 through 3.14, Since breaks had been expected, protective conduit had been used to prolong the recording time. This precaution proved to have been worthwhile. All acceleration traces displayed a rather rounded waveform and at Stations 1 and 6, noticeably flattened peaks of constant accel eration occurred. This can be accounted for in the case of Station 1, at least in part, by the aforementioned gage over ranging. The flattened peak on Gage 6A, however, is considered to be a realistic waveform in view of -che fact that velocity data BEST AVAILABLE COPY

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BEST AVAILABLE COPY derived from it agrees with data from Gage GV quite well with respect torboth peak value and time of occurrence of the peak. Figure 3.33 shows the vertical acceleration data taken from EH-5 plotted versus slant range, A "best-fit'' line drawn through the first four points, which were free of surface effects, shows an attenuation rate as the -2.3 power of slant range. This attenu ation rate is in reasonable agreement with the -2.9 power which had been predicted. The actual measured magnitudes, however, were roughly double the predicted values. It is evident from Figure 3.33 that the free surface effect was noticed and, in fact, affected the motion at a depth of 100 ft. The motions both there and at the surface station are approximately double what might be expected from an extension of the "best-fit" line described previously. Some information concerning depth of spalling can be determined from the accelerograms obtained above the shot point. The trace from Station 1 (Figure 3.1, and, on an expanded time scale, Figure 3,3) shows a second upward pulse occurring at about 36 msec after the first arrival. Assuming this pulse is the compressive wave arriving back at the surface after reflecting from a spall gap, the depth to the spall gap is computed to be approximately 200 ft. The traces from Stations 1, 2, and 3 show multiple reflections after the first, probably .indicating multiple spalls at various depths. BEST AVAILABLE COPY

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BEST AVAILABLE COPY Figure 3.33 Vertical acceleration versus slant BEST AVAILABLE COPY

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BEST AVAILABLE COPY jrigure 3.34 shows vertical downhole (free-field) particle velocity as measured by the velocity gages, plotted versus slant range. A least-squares fit to the data is shown, the line being and R in feet. Here again the attenuation rate is quite close to the rate 1.80 which was predicted, but, as before, the magni tudes measured are roughly double the predicted values. Figure 3.35 is a plot of vertical surface particle velocity versus slant range, A least-squares fit to the data yields the ation rate …