TY  - JOUR
AU  - Zaroli Christophe, Debayle Eric
PY  - 2010//
TI  - Frequency-dependent effects on global S-wave traveltimes: wavefront-healing, scattering and attenuation
JO  - Geophysical Journal International
SP  - 1025
EP  - 1042
VL  - 182
IS  - 2
N2  - We present a globally distributed data set of 400 000 frequency-dependent SH-wave traveltimes. An automated technique is used to measure teleseismic S, ScS and SS traveltimes at several periods ranging from 10 to 51 s. The targeted seismic phases are first extracted from the observed and synthetic seismograms using an automated time window algorithm. Traveltimes are then measured at several periods, by cross-correlation between the selected observed and synthetic filtered waveforms. Frequency-dependent effects due to crustal reverberations beneath each receiver are handled by incorporating crustal phases into WKBJ synthetic waveforms.After correction for physical dispersion due to intrinsic anelastic processes, we observe a residual traveltime dispersion on the order of 12 s in the period range of analysis. This dispersion occurs differently for S, ScS and SS, which is presumably related to their differing paths through the Earth. We find that: (1) Wavefront-healing phenomenon is observed for S and to a lesser extent SS waves having passed through very low velocity anomalies. (2) A preferred sampling of high velocity scatterers located at the CMB may explain our observation that ScS waves travel faster at low-frequency than at high-frequency. (3) A frequency-dependent attenuation q() q0×, with  0.2, is compatible with the globally averaged dispersion observed for S waves.
SN  - 0956-540X
UR  - http://dx.doi.org/10.1111/j.1365-246X.2010.04667.x
N1  - exported from refbase (http://publi.ipev.fr/polar_references/show.php?record=455), last updated on Mon, 01 Jul 2024 14:29:02 +0200
ID  - ZaroliChristophe2010
ER  -