Abstract

Seismic attenuation is an important parameter for characterizing subsurface morphology and thermal structure. In this study, we use P-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 the P-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.

Department(s)

Geosciences and Geological and Petroleum Engineering

Comments

The study was partially supported by the U.S. National Science Foundation under Grant No. 1919789.

Keywords and Phrases

Continental Lithosphere; Seismic Wave Attenuation; Upper Mantle

Geographic Coverage

Southeastern United States

International Standard Serial Number (ISSN)

1525-2027

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2021 American Geophysical Union, All rights reserved.

Publication Date

01 Jun 2021

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