Comparing P and S Wave Speed Perturbations for Europe

This study aims to improve our understanding of the temperature and composition of the mantle underneath Europe. We selected bodywave traveltime residuals of common source-receiver pairs from the reprocessed dataset of Engdahl and others. Due to the one to one correspondence between the P and S sampling, the resulting P and S wavespeed perturbation models have a similar ray coverage and therefore similar resolution properties. From these models we extracted the bulk sound speed, Poisson's ratio and R=∂ lnV_s/∂ lnV_p. The preliminary results show an almost constant R of 0.8 throughout the mantle except in the transition zone. Furthermore, we find a substantial difference in the Poisson's ratio between the cratonic and tectonic part of Europe. The bulk sound speed and shear wavespeed perturbations appear to be negatively correlated in most of the mantle. The correlation of the P and S wavespeed perturbations is positive and decreasing until ∼1500 km depth, in agreement with previous studies.