The full wave theoretic fast field/reflectivity method [Schmidt and Tango, Geophys. J. R. astro. Soc., March, 1986] is applied to determining the propagation characteristics governing reception of intermediate and long range low frequency seismo-acoustic signals, by horizontal and vertical arrays of hydrophones and geophones. Seismically equivalent stratigraphic models for fine-scale sediment P and S wave velocity are examined for a thickly sedimented DSDP site in the western North Atlantic, to determine the relative effects of P-S conversion, intrinsic attenuation, and stratigraphic layer transmission loss, on predicted signal strength level and coherence vs source receiver range, depth, and sensor depth. Synthetic CW reflection and transmission loss, in conjunction with synthetic OBS and VSP data, reveal an overall trend of monotonically decreasing signal level with depth, interrupted by localized zones of relatively lower (3-7 dB) signal loss, in agreement with synthetic and experimental borehole data from exploration seismic studies [Keho et al, 1984]. Within the seafloor, shear-specific loss effects may be as great as 10+ dB on the vertical component geophone. Only at isolated ranges does the vertical component exceed in signal level the horizontal component geophone or pressure hydrophone. The "optimum" subbottom depth for triaxial geophones and colocated hydrophones (i.e., minimum ambient noise and signal interference with direct and multiply-reflected water arrivals) is governed by the absolute level and directionality of ambient noise, seafloor boundary roughness, shear wave velocity, and depth to basement, or equivalent stratigraphic target zones.

West: -80.0000 East: 20.0000 North: 75.0000 South: .0000

West: NaN East: NaN North: NaN South: NaN

Expedition: 76

Site: 76-534

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=1991-013661 (c.f. for more detailed metadata)

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