Joint inversion of a new global data set of teleseismic P and SV arrival times and the waveforms of surface and regional body waves

Surface wave tomography yields high resolution models for the seismic velocities
in the earth’s upper mantle. To extend the imaging into the mantle transition
zone and into the lower mantle below, additional constraints from teleseismic
body waves, which probe these deeper regions, are needed. Here, we combine a
large new dataset of teleseismic P and SV travel times obtained via an automatic
picking algorithm (Stampa et al., 2024), with waveform fits from Automated
Multimode Inversion (AMI; e.g. Dou et al. (2024)) in a joint inversion. The
sensitivity volumes for the teleseismic body waves used in the inversion are
approximated using ray tracing in a spherically symmetric background model.
For the P and SV arrival-time data sets, travel-time corrections are calcu-
lated to account for the differences induced by the ellipticity of the earth. The
frequency-dependent effects of anelasticity on the propagation of the teleseismic
waves are estimated and accounted for, using the measured central frequencies
of the waves’ arrivals. Travel time anomalies resulting from crustal structure
are estimated and accounted for using the ECM1 crustal model.
The preliminary results show a marked improvement in the resolution of
structure at depths below 400 km, in particular in regions of dense station
coverage, including Europe, North America, and the subduction zone regions
around the Pacific Ocean.

 

References

Dou, H., Xu, Y., Lebedev, S., de Melo, B. C., van der Hilst, R. D., Wang, B., &
Wang, W., 2024. The upper mantle beneath Asia from seismic tomography,
with inferences for the mechanisms of tectonics, seismicity, and magmatism,
Earth-Science Reviews, 255, 104841.

Stampa, J., Eckel, F., Keers, H., Lebedev, S., Meier, T., & AlpArray and
SWATH-D Working Groups, 2024. Automated measurement of teleseismic
P-, SH-and SV-wave arrival times using autoregressive prediction and the
instantaneous phase of multicomponent waveforms, Geophysical Journal In-
ternational , 239(2), 936–949