Velocity structure of the Northern Mississippi embayment sediments, part II: Inversion of teleseismic P-wave transfer functions


Detailed shear and compressional gradient velocity structure for the unconsolidated sediments of the Mississippi Embayment (ME) have been obtained through simultaneous inversion of radial and vertical teleseismic transfer functions for 60 broadband stations inside the ME. Transfer functions were calculated by deconvolving a vertical array beam from the radial and vertical displacement at each station inside the embayment. The vertical array beam was constructed by stacking all the vertical components of motions for stations on the bedrock and outside the embayment to reduce the effect of incoherent scattering, improving estimates of the source time function and stabilizing the deconvolution. A bounded variable leastsquares inversion technique was applied to invert for velocity nodes on the top and bottom of the sediment layer. P-wave velocity changes from 1:0 km=s near the surface and increases with depth from 3.5 to 4 km=s in deeper parts. S-wave velocity varies from 0:3 km=s and increases to 1:6 km=s in deeper sections to the south.

Publication Title

Bulletin of the Seismological Society of America