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Abstract Seismic attenuation is an important parameter for characterizing subsurface morphology and thermal structure. In this study, we useP‐wave amplitude spectra from 588 teleseismic events recorded by 477 broadband seismic stations in the southeastern United States to examine the spatial variations of seismic attenuation in the crust and upper mantle. The resulting seismic attenuation parameter (∆t*) measurements obtained using the spectral ratio technique reveal a zone of relatively low attenuation in the Gulf of Mexico Coastal Plain and the southwestern terminus of the Piedmont province. Spatial coherency analysis of the ∆t* observations suggests that the center of the low attenuation layer is located within the uppermost mantle at about 70 km depth. This low attenuation anomaly lies along the suture zone between Laurentia and Gondwana and approximately coincides with the east‐west trending Brunswick magnetic anomaly. The origin of this low attenuation anomaly can be attributed to low attenuation bodies in the form of remnant lithospheric fragments in the deep crust and the uppermost mantle. The contribution of scattering to the observed ∆t* is estimated by calculating the ratio of amplitude on the transverse and vertical components in theP‐wave window. Relative to the rest of the study area, the Gulf of Mexico Coastal Plain demonstrates weaker scattering which is suggestive of a more homogenous crustal and uppermost mantle structure.
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Teleseismic attenuation beneath the British Isles
SUMMARY The British Isles' lithospheric structure, shaped by a dynamic geological history, remains incompletely understood, particularly regarding anelastic parameters, such as attenuation. In this study, we present a teleseismic attenuation model for the British Isles, using time-domain analysis of teleseismic P-wave data from 28 deep earthquakes. We constructed a 2-D differential attenuation map (Δt*) that reveals significant regional variations. Our findings show a weak anticorrelation between Δt* and shear wave velocity at upper mantle depths, suggesting that variations in the lithosphere–asthenosphere system influence this pattern. A high-attenuation zone extends from Scotland across the Irish Sea to southwest England, potentially linked to mantle upwelling associated with the Iceland plume. This model provides new insights into the mantle dynamics beneath the British Isles, offering a crucial reference for future geophysical studies in the region.
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- Award ID(s):
- 1944998
- PAR ID:
- 10613431
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Geophysical Journal International
- Volume:
- 242
- Issue:
- 2
- ISSN:
- 0956-540X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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