Hoskins Hartley

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  • Technical Report
    Data report of oblique reflection-refraction radio-sonobuoy profiles on the African Atlantic continental margin : (R/V Atlantis II cruises 67 and 75)
    (Woods Hole Oceanographic Institution, 1974-06) Hoskins, Hartley ; Rogers, Carolyn U. ; Woo, Aileen O.
    Two hundred sixty-four unreversed oblique reflection-refraction profiles using expendable radio-sonobuoys were obtained during two geophysical cruises to the Atlantic continental margin of Africa. This data report gives the profile locations, a summary of the data collection and analysis, and 780 interval reflection and refraction velocities and thicknesses that were determined.
  • Article
    Third-party borehole seismic experiments during the Ocean Drilling Program
    (Copernicus Publications on behalf of the German Research Centre for Geosciences, 2007-11) Stephen, Ralph A. ; Swift, Stephen A. ; Bolmer, S. Thompson ; Hoskins, Hartley
    The first borehole seismic experiments on DSDP and ODP were two-ship Oblique Seismic Experiments (Stephen, 1979; Stephen, et al., 1979, 1980; Swift, et al., 1988). By recording on the drill ship and shooting explosives out to ranges of 8 km, the upper 1.5 km of the upper crust (Layer 2) adjacent to the borehole could be imaged (Fig. 1; Stephen and Harding, 1983), Azimuthal anisotropy (Stephen, 1981, 1985) and lateral heterogeneity (Stephen, 1988; Swift and Stephen, 1989) could also be studied by shooting circles of shots at a fixed range from the borehole,
  • Working Paper
    Transcription of 9-track tapes to CD-ROM
    (Woods Hole Oceanographic Institution, 1999-12) Bolmer, S. Thompson ; DuBois, David L. ; Hoskins, Hartley ; Sass, Warren J.
    The WHO! Marine Seismic community had about two thousand 9-track magnetic tapes in storage. The data stored were from marine experiments dating from the 1970's to 1990 and from computer models. The experiments included observations made with seafloor instruments and sondes in boreholes. These tapes were created on Digital Equipment Corporation (DEC) V AXNMS and other older computer operating systems. The tapes needed to be read and put into a format that contemporary UNIX operating systems could read. This report documents the logistics of transcribing this information onto CD-ROM. A search was made to find the best way to read and rewrite these 9-track tapes to new media that would have a longer shelflife and be readable on today's UNIX variants. As a result of this search, an outside company was hired to do these conversions. The tapes that were readable from this first group of 381 tapes selected for transcription are now on twenty-five CDROMs.
  • Presentation
    Third party borehole seismic experiments during the Ocean Drilling Program [poster] 
    ( 2003-12) Swift, Stephen A. ; Stephen, Ralph A. ; Hoskins, Hartley ; Bolmer, S. Thompson
    Third party borehole seismic experiments on the Ocean Drilling Program began with an oblique seismic experiment on Leg 102 at Site 418 in the Western Atlantic. Upper ocean crust here is characterized by a normal seismic layer 2 vertical velocity gradient, lateral velocity variations, azimuthal anisotropy, and azimuth dependent scattering. A normal incidence VSP was run on Leg 118 in the gabbro sequence at Hole 735B on the Southwest Indian Ridge. The vertical seismic velocity inferred from arrival times is similar to that observed horizontally by refraction in ocean layer 3, but attenuation is anomalously high, which prompted the hypothesis that the gabbro cored may not actually represent the bulk of Layer 3 material. The VSP data acquired at Hole 504B in the eastern equatorial Pacific on Legs 111 and 148 helped to constrain the P and S velocity structure at the site and showed that upper layer 3 at this site, at a depth of over 2 km into the crust, consisted of the lower portion of the sheeted dikes rather than gabbro. Both offset and normal incidence VSPs were run on Leg 164 to study the seismic velocity structure of gas hydrates on the Blake Ridge. A new innovation on ODP was the deployment of broadband seismometers in boreholes. Whereas the conventional VSPs and offset VSPs mentioned above operate in the frequency range from 1 to 100Hz, broadband seismometers are used in earthquake seismology and operate in the range from 0.001 to 10Hz. The first broadband seismometer test was carried out from the drill ship on Leg 128 in the Japan Sea. Subsequently 4 permanent broadband borehole seismic observatories were installed in the Western Pacific and Japan Trench on Legs 186, 191 and 195. The ODP era also saw the development of systems for re-entering boreholes from conventional research vessels after the drill ship left the site. Borehole seismic experiments and installations that used this wireline re-entry technology were carried out in DSDP Holes 534 (Blake-Bahama Basin) and 396 (Mid-Atlantic Ridge at 23degr north) and ODP Hole 843B (south of Oahu). The latter experiment (Ocean Seismic Network Pilot Experiment) carried out a test of 3 configurations of broadband seafloor seismic installation in preparation for extending the Global Seismic Network to the deep ocean.
  • Working Paper
    Technical summary of USGS OBS operation R/V JOIDES Resoultion, ODP leg 179
    (Woods Hole Oceanographic Institution, 2001) Busby, Robert W. ; Hoskins, Hartley
    The experiment was to determine if a technique known as "Seismics While Drilling" was a viable means of gathering seismic images of near hole structure without consuming any rig time. The idea is to use a correlation technique between the drill bit vibrations and seismometers installed at the seafloor much like an inverted Vertical Seismic Profile (VSP). LDEO Borehole Group constructed and operated the pilot sensor consisting of a three axis accelerometer and mounted on the drill string. USGS OBS were deployed on the ocean floor within a few hundred meters of the drill hole. At the first site, (deploy! Hole 1104E) a hammer drill bit was recorded as a sort of warmup drop and out of curiosity as to how this might compare to the other drilling which used a roller cone coring bit and a regular tri-cone bit. This was a short session lasting less than 24 hours. The next deployment, deploy2 Hole II OSA, was during a coring operation that lasted seven days with core to depth of 154m with no sediments. During this period the pilot sensor operated for 2.5 days. The final deployment, deploy3 Hole 1107A, was during the drilling of 370m of sediment and 114m of basement below the sediment. The pilot sensor operated during 36 hours of the drilling, through the sediments and 45 meters into basement. In addition to the drilling recordings, a few tests were performed to assist the processing phase. First a dockside test with all three sensors located side by side on the dock in Cape Town was recorded, deploy 0 called dock or dockside . This data was shipped back before sailing to prime the data format conversion process. Two OBS diagnostic tests were recorded aboard the ship to test noise levels of amplifier electronics, Preamp I and Preamp2. Finally, a sine wave generator was connected to an OBS and the pilot sensor recorder at the same time in order to ensure time labelling consistency and provide an easy signal to compare against for data conversion methods, called sinesync. A few lines of refraction shooting by the F/S Sonne were also recorded during deploy3 at Hole 1107A. These were part of the SINUS project which was supposed to include recording of a borehole seismometer at the bottom of the hole. The JOIDES Resolution ran out of time and was unable to complete this portion of the experiment. LDEO Borehole announced at the outset of the cruise they would withhold all pilot sensor data and deliver it after the cruise. Thus no shipboard correlation was possible. It is unlikely operations could have been altered much in any case.