Open AccessAnelasticity of the Crust and Upper Mantle beneath the Pacific Ocean from the Inversion of Observed Surface Wave Attenuation
Author(s) -
Mitchell Brian J.
Publication year - 1976
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1976.tb01246.x
Subject(s) - geology , crust , attenuation , pacific ocean , seismology , inversion (geology) , geophysics , upper crust , oceanic crust , mantle (geology) , oceanography , subduction , tectonics , physics , optics
Summary Backus‐Gilbert inversion theory is applied to a new set of surface‐wave attenuation data to obtain average Q β −1 models for the crust and upper mantle beneath the Pacific Ocean. The favoured model is obtained from the inversion of Rayleigh‐wave data alone. It includes an increase in Q −1 (or decrease in Q ) at depths corresponding to the thickness of the litho‐sphere as determined from surface‐wave velocity studies, a thick zone of high Q −1 (or low Q ) in the upper mantle, and decreasing Q β −1 deeper in the mantle. The mean Q −1 values for the lithosphere are lower than those previously determined for the lower crust beneath continents. Simultaneous inversions of the Love‐ and Rayleigh‐wave data yield models which include thin, alternating regions of high and low Q −1 values. Independent inversions of the Love‐ and Rayleigh‐wave data yield models which differ in their anelastic properties at depths between 20 and 120km. These latter two types of models probably reflect systematic errors in the Love‐wave data due to higher mode interference or complexities along the propagation path.