Articles | Volume 6, issue 4
Research article
09 Oct 2015
Research article |  | 09 Oct 2015

Measuring and crust-correcting finite-frequency travel time residuals – application to southwestern Scandinavia

M. L. Kolstrup and V. Maupin

Abstract. We present a data-processing routine to compute relative finite-frequency travel time residuals using a combination of the Iterative Cross-Correlation and Stack (ICCS) algorithm and the Multi-Channel Cross-Correlation method (MCCC). The routine has been tailored for robust measurement of P- and S-wave travel times in several frequency bands and for avoiding cycle-skipping problems at the shortest periods. We also investigate the adequacy of ray theory to calculate crustal corrections for finite-frequency regional tomography in normal continental settings with non-thinned crust. We find that ray theory is valid for both P and S waves at all relevant frequencies as long as the crust does not contain low-velocity layers associated with sediments at the surface. Reverberations in the sediments perturb the arrival times of the S waves and the long-period P waves significantly, and need to be accounted for in crustal corrections. The data-processing routine and crustal corrections are illustrated using data from a~network in southwestern Scandinavia.

Short summary
We present a data-processing routine for robust measurements of relative arrival times of P and S waves, filtered in different frequency bands and recorded at regional networks of seismological stations. We also analyse the influence of crustal structure on the arrival times of P and S waves, and find that arrival times are generally different in different frequency bands in the presence of sedimentary layers. These findings are illustrated using data from southwestern Scandinavia.