Open AccessAnelasticity of the crust and upper mantle beneath the Eurasian continent and the nearby regions from the inversion of Love and Rayleigh wave attenuation data
Author(s) -
Singh D. D.
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.tb02796.x
Subject(s) - lithosphere , geology , rayleigh wave , attenuation , seismology , crust , mantle (geology) , love wave , rayleigh scattering , geophysics , continental crust , amplitude , surface wave , oceanic crust , geodesy , tectonics , wave propagation , longitudinal wave , subduction , mechanical wave , physics , optics , quantum mechanics , astronomy
Summary The fundamental mode Love and Rayleigh waves generated by five earthquakes, which occurred in central Asia and were recorded at 20–35 WWSSN stations throughout the world, are analysed. The Love and Rayleigh wave attenuations are determined at the time period of 10–120 s for the continental and oceanic paths across Eurasia and nearby regions using the spectral amplitudes of these waves. The large standard deviation observed in the attenuation coefficients of surface waves may be due to the regional variation of the attenuative properties of the crust and upper mantle beneath Eurasia. The continental Rayleigh wave attenuation coefficients are smaller by a factor of up to 2 compared to oceanic paths. The continental Rayleigh wave attenuation coefficient attains two minima of 0.15 × 10 ‐3 and 0.11 × 10–3 km ‐1 at the time periods of 35 and 80s respectively, and two maxima of 0.58 × 10 ‐3 and 0.3 × 10 ‐3 km ‐1 at time periods of 10 and 100s respectively. A similar trend is observed for the oceanic paths as well. Backus and Gilbert inversion theory is applied to these Love and Rayleigh waves attenuation data to obtain Q ‐1 β models for the crust and upper mantle beneath Eurasia and the nearby regions. Independent inversion of continental Love and Rayleigh waves attenuation data yields the thickness of the lithosphere to be 90 km. For the oceanic paths, the thickness of the lithosphere is estimated to be 110 km. The base of the lithosphere is identified as the depth at which Q ‐1 β increases sharply. Q ‐1 β in the asthenosphere is greater to a minimum of a factor of 2 as compared to the lithosphere.