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Long range shnc4 1I'0\'es frOIl1 a large C.\p10510/1 IInderll'alcr: cxpcrimenl alld dala further by comparing seismically interpreted velocity-depth models with known outcrop or borehole rock physical properties, extending the range of geological interpreted models using physical measurement from seismics. These gradual refinements in measurement should contribute to assessing specific geological provinces, for example, in the present case, the rocks of the Midland Valley Carboniferous (e.g. see Browne et aI, 1985, 1987). Offshore, the deployment of PUSSes will provide an opportunity to observe the interface (Scholte and Stonely) waves which may be generated and hence, to measure the shear wave structure of the unconsolidated sediments. In general the experiment allows further development and application of the use of high frequency Rayleigh waves (1 Hz) in the measurement of physical properties of rocks ill silll, to help discern the physical properties of deep geological structure. 18
Long range shock waves from a large explosion underwater: experiment and data 3. METHODS AND EQUIPMENT The general layout of the equipment is shown in Figs 2.2 and 2.3, with PUSSes at sites 1-6 and a vertical hydrophone string and the BGS Sea Bottom Package (SBP) at the site marked BGS. The major items of equipment were photographed and can be seen at the end of the report. MSF Rugby was recorded as a time standard on all BGS systems. 3.1 RECORDING PACKAGES AND TRANSDUCERS 3.1.1 Pressure Gauges Piezo electric pressure gauges (type: Piezotechnics TX - lAP - CE) were deployed in two vertical arrays of six cable-linked to Goosander. The signal from each gauge was recorded at two different sensitivity levels on a store - 14D5 recorder. The general arrangement of the gauges and their sensitivities are given in Tables 3.1 and 3.2 respectively, as provided by ARE. The presentation and analysis of the data will be dealt with in subsequent reports. 3.1.2 Shot Timing Equipment In order to determine the velocity of seismic arrivals across the array it is essential to know the shot instant accurately. Two independent systems were installed on the Goosander in an attempt to be failsafe. The· first system was designed around a Store-7 recorder with a 5tore-14 as a back-up. The second system was a digital recorder programmed to switch on automatically for each of the scheduled ten minute shot windows. MSF and OCF time standards, along with one geophone, one hydrophone and the shot firing pulse, were recorded on each system. The geophones were fixed to the ships hull and the hydrophones were suspended in the sea. As only the first onset from the shockwave was important the recording sensitivity levels were not critical. The arrival times at the geophones and hydrophones are corrected for the travel-time between the shot and Goosander's stand-off position. The shot instant was also obtained by recording the shot pulse from the firing mechanism. The configuration of the shot timing systems is shown in Fig. 3.1. 19
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Page 11 and 12: Appendix G: Picking list for travel
Page 13 and 14: Figures Fig. 2.1 Fig. 2.2 Fig. 2.3
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Page 41: Long range shock waves from a large
Page 61: Acknovledgeaents For producing the
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01 01 Table 5.1 Explosion shot time
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(a) fname Table 7.1 Header block co
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Table 8.1 Comparison of measured ex
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Step 1 GEMINI takes 55Kg weight att
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90 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
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Appendix A: Proposed schedule for L
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16:47:00 16:47:20 16:47:30 16:47:34
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08:12:45 08:12:50 08:13:00 08: 13:2
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PUSS 3 (INSTRUMENT 11) REDEPLOYED 2
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PUSS 6 (INSTRUMENT 14) REDEPLOYED 2
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Appendix C: Locations of sites at s
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(2) PUSS LOCATIONS SITE 1 (PUSS 2)
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Fix: 56°42.810N aN = .001N +1 m 01
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Appendix D: MODELS FOR COMPUTER SIM
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.... N Table D2 Paraaeters of preli
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(c) Permanent land stations with a
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4 13 5 14 Hydr. z x y Hydr. z x y R
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5 14 Hydr. Z X y Hydr. z X y First
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F.3.9 PUSS 10 at 9.982 km, 9001b sh
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I-' W en Fig. F.1.2 PUSS 11. RANGE=
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.... w
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.... t Fig. F .1.10 PUSS 11, RANGE=
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.... (JI .... Fig. F.2.2 PUSS 11. R
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I-' U1 CD Fig. F.2.1O PUSS 10, RANG
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.... m I\) Fig. F.2.13 PUSS 13, RAN
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Fig. F.2.16 BGS Sea Vertical Hydrop
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I-' -oJ w Fig. F.3.6 BGS Sea Bottom
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I-' ()) 0 Fig. F.3.13 BGS Sea Botto
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.... (J) 0 Fig. F.3.13 BGS Sea Bott
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Start of record = 11:52:05.0 Filena
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Start of record = 15:22:05.0 Filena
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BGS VHS Start of record = 11:53:13.
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Plate 16 Plate 17 Plate 18 Plate 19
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Plate 4 Plate 5 Plate 6
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Plata 10 Plate 1 1 Plate 12
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Plate 16 Plate 17 Plate 18
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Plate 22 Plate 23
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Plate 28 Plate 26
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