scholarly journals Constraints on the upper mantle structure beneath the Pacific from 3‐D anisotropic waveform modelling

2021 ◽  
Author(s):  
E. Kendall ◽  
A.M.G. Ferreira ◽  
S.‐J. Chang ◽  
M. Witek ◽  
D. Peter
Keyword(s):  
Upper Mantle ◽  
Mantle Structure ◽  
The Pacific ◽  
Upper Mantle Structure ◽  
Waveform Modelling

Variations of Upper Mantle Structure under the Pacific Ocean

Science ◽  
1974 ◽  
Vol 186 (4159) ◽  
pp. 141-143 ◽  
Author(s):  
A. R. Leeds ◽  
L. Knopoff ◽  
E. G. Kausel
Keyword(s):  
Pacific Ocean ◽  
Upper Mantle ◽  
Mantle Structure ◽  
The Pacific ◽  
Upper Mantle Structure ◽  
The Pacific Ocean

Upper Mantle Structure beneath the Mid-Atlantic Ridge from Regional Waveform Modeling

2020 ◽  
Vol 110 (1) ◽  
pp. 18-25 ◽  
Author(s):  
Ingo Grevemeyer
Keyword(s):  
Upper Mantle ◽  
Velocity Structure ◽  
Vertical Component ◽  
Depth Interval ◽  
Mantle Structure ◽  
Waveform Modeling ◽  
Spreading Ridges ◽  
The Pacific ◽  
Upper Mantle Structure ◽  
Mid Atlantic Ridge

ABSTRACT The lithosphere is the outermost rigid layer of the Earth and includes the crust and brittle uppermost mantle. Because the poor seismic coverage of the ocean basins is the mantle structure of young lithosphere below midocean spreading centers poorly constrained, especially along slow spreading ridges. Surface waves radiated by midocean ridge earthquakes are excellent agents to study young lithosphere when being recorded in the vicinity of the ridge crest. Here, we use body and Rayleigh waves from six central Atlantic transform fault earthquakes with magnitude Mw>6 to constrain upper mantle structure away from ocean islands. Earthquakes were recorded by a network of broadband ocean-bottom seismometers deployed at the Mid-Atlantic Ridge (MAR) near 14°45′ N. Waveform modeling of vertical-component data at periods of 10–60 s yielded the velocity structure of the uppermost ∼100  km of the mantle and hence of the depth interval where lithospheric cooling is most evident. The data support that both S-wave velocity of the lithospheric lid and its thickness increases with age; velocities increase from 4.35 to 4.75  km/s and thickness from 30–50 to 70 km, sampling mantle with an average path age of ∼7 and 18 My, respectively. With respect to constraints found previously in the Pacific, lid velocities beneath the MAR are faster than beneath fast-spreading ridges, whereas asthenospheric velocities are similar to the Pacific. The fast velocity of the lid and slow velocity of the inversion zone may indicate effective hydrothermal cooling of the lithosphere.

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