|Title||A comprehensive dispersion model of surface wave phase and group velocity for the globe|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Ma Z.T, Masters G., Laske G., Pasyanos M.|
|Journal||Geophysical Journal International|
|Type of Article||Article|
|Keywords||anisotropic structure; least-squares; love; maps; pacific; polarization data; rayleigh-waves; seismic anisotropy; seismic tomography; Shear; Surface waves and free oscillations; upper-mantle|
A new method is developed to measure Rayleigh- and Love-wave phase velocities globally using a cluster analysis technique. This method clusters similar waveforms recorded at different stations from a single event and allows users to make measurements on hundreds of waveforms, which are filtered at a series of frequency ranges, at the same time. It also requires minimal amount of user interaction and allows easy assessment of the data quality. This method produces a large amount of phase delay measurements in a manageable time frame. Because there is a strong trade-off between the isotropic part of the Rayleigh-wave phase velocity and azimuthal anisotropy, we include the effect of azimuthal anisotropy in our inversions in order to obtain reliable isotropic phase velocity. We use b-splines to combine these isotropic phase velocity maps with our previous group velocity maps to produce an internally consistent global surface wave dispersion model.
"These maps provide a very compact way to represent our data sets and give over 90 per cent of variance reduction for most frequencies for both Love and Rayleigh waves.... Large-scale geological features and clear age-progression trends of both group and phase velocities in the ocean basins can be resolved. These maps provide useful constraints on the velocity of the crust and uppermost mantle and are currently being used to produce a new global lithosphere model."