Open AccessRayleigh wave anelastic attenuation across the Bermuda Rise and the volcanic Caribbean Arch
Author(s) -
Canas José A.
Publication year - 1982
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1982.tb02793.x
Subject(s) - attenuation , geology , seamount , rayleigh wave , volcano , seismology , seafloor spreading , rayleigh scattering , geophysics , surface wave , oceanography , physics , optics
Summary Average fundamental mode group velocities and attenuation coefficients of Rayleigh waves have been obtained in a region of the Western North Atlantic comprising the Bermuda Rise, the volcanic Caribbean Arch, and normal seafloor greater than 65 Myr in age. The average Rayleigh wave attenuation coefficients decrease from a value of 7.78 times 10 ‐4 km ‐1 at a period of 15s to a value of 0.21 times 10 ‐4 km‐1 at a period of 100 s. Attenuation values and Q R factors obtained are characteristic of a young oceanic region, and they do not correspond to a typical region greater than 65 Myr in age. It is apparent from the data that the high attenuation values reported are due to the effect that the back‐arc basin behind the Caribbean Arch has on Rayleigh wave attenuation. Inversion theory applied to the attenuation data yields a Q ‐1 β model presenting the same features as those corresponding to extension zones such as the spreading centres of the Atlantic and Pacific Oceans. The low‐Q region in the model is situated between depths of around 15 and 100 km, with the maximum Q ‐1 β value (˜17 times 10 ‐3 )occurring at about 50 km depth.