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Elastic properties of seafloor sediments from the modelling of amplitudes of multiple water waves recorded on the seafloor off Bear Island, North Atlantic
Author(s) -
Grad Marek,
Mjelde Rolf,
Czuba Wojciech,
Guterch Aleksander
Publication year - 2012
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.2011.01022.x
Subject(s) - seafloor spreading , geology , sedimentary rock , lithology , seismometer , amplitude , attenuation , mineralogy , seismology , petrology , oceanography , geochemistry , physics , quantum mechanics , optics
Wide‐angle seismic data acquired by use of air‐guns and ocean bottom seismometers (OBS) contain strong direct water arrivals and multiples, generally considered as noise and thus not included in the modelling. However, a recent study showed that standard ray‐tracing modelling of the water multiples recorded off the Bear Island, North Atlantic, provided a reliable estimate of the velocity distribution in the water layer. Here, we demonstrate that including the amplitudes in the modelling provide valuable information about the V P contrast at the seafloor, as well as the V P /V S ratio and attenuation ( Q P ) of the uppermost sediments. The V P contrast at the seafloor is estimated at about 250 m/s, within a precision of approximately ±30 m/s. The V P /V S ratio in the uppermost sedimentary layer is modelled in the range 2.25–2.50 and the Q P factor is estimated at 1000 for the water, 30–50 for the uppermost layer and 40–50 for the second sedimentary layer. The values obtained for the sediments suggest a lithology dominated by silty clays, with porosity below average.