Attenuation of P-waves in oceanic crust; multiple scattering from observed heterogeneities

Online Access: Get full text
doi: 10.1029/94GL01855
Author(s): Goldberg, D.; Yin, C. S.
Author Affiliation(s): Primary:
Lamont-Doherty Earth Observatory, Palisades, NY, United States
Volume Title: Geophysical Research Letters
Source: Geophysical Research Letters, 21(21), p.2311-2314. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276 CODEN: GPRLAJ
Note: In English. Lamont-Doherty Earth Observatory Contrib. No. 5220. 21 refs.; illus.
Summary: We extend a model for seismic attenuation that includes scattering and intrinsic components, Q -1 = Qs -1 + Qi -1, over five decades in experimental wavelength. Core images and downhole logs from Ocean Drilling Program Hole 735B near the Atlantis II Fracture Zone in the Indian Ocean were used to construct vertical profiles of heterogeneity and to compute a spectrum of Qs -1 using a multiple scattering model. Measurements of velocity dispersion suggest that Qi -1 is small compared to the measured attenuation Q -1. Measurements of Q -1 made at this site by laboratory, sonic log and VSP experiments are compared to the computed Qs -1 spectrum. Peaks in the Qs -1 spectrum occur at six major correlation lengths scales (0.006 m, 0.02 m, 0.16 m, 0.63 m, 8.0 m, and 25.0 m) which can be attributed to formation heterogeneity. Compared to typical seismic estimates of Q -1 in oceanic Layer 3, the measurements in Hole 735B are high, but can be explained by large Qs -1 values in shallow, fractured ocean crust. Based on this comparison, we conclude that the proximity of the experimental wavelength in band-limited studies to the length scale of heterogeneity is critical in the measurement of Q -1. Copyright 1994 by the American Geophysical Union.
Year of Publication: 1994
Research Program: ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Atlantis II fracture zone; Attenuation; Body waves; Crust; Elastic waves; Heterogeneity; Indian Ocean; Leg 118; Models; ODP Site 735; Ocean Drilling Program; Oceanic crust; P-waves; Q; Seismic waves; Seismology; Wave dispersion
Coordinates: S324327 S324318 E0571618 E0571557
Record ID: 1996027044
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute.