Global reference seismological data sets: multimode surface wave dispersion

SUMMARY Global variations in the propagation of fundamental-mode and overtone surface waves provide unique constraints on low-frequency source properties structure Earth’s upper mantle, transition zone mid mantle. We construct a reference data set multimode dispersion measurements by reconciling large diverse catalogues Love-wave (49.65 million) Rayleigh-wave (177.66 from eight groups worldwide. The summarizes up to six branches 44 871 earthquakes recorded 12 222 globally distributed seismographic stations. Dispersion curves are specified at periods between 25 250 s determine propagation-phase anomalies with respect Earth model. Our procedures for sets include: (1) controlling quality salvaging missing metadata; (2) identifying discrepant reasons discrepancies; (3) equalizing geographic coverage constructing summary rays travel-time observations (4) phase velocity maps various wavelengths combination types evaluate inter-dataset consistency. retrieved station earthquake metadata several legacy compilations codified scalable formats facilitate reproducibility, easy storage fast input/output high-performance-computing systems. Outliers can be attributed cycle skipping, polarity issues or interference specific epicentral distances. By assessing consistency across similar paths, we empirically quantified uncertainties traveltime measurements. More than 95 per cent internally consistent, but agreement deteriorates overtones especially 5 6. Systematic discrepancies raw techniques theoretical approximations, models processing schemes. Phase-velocity yielded inversion highly correlated (R ≥ 0.8) those quality-controlled contributing sets. Long-wavelength (50–100 s) largely independent measurement technique high correlations extending degree ∼25. Agreement degrades increasing branch number period; is found only ∼10 longer (T > 150 ∼8 overtones. Only 2ζ azimuthal Rayleigh were required set; consistent ( R = 0.6–0.8). Reference useful improving existing techniques, validating interior structure, calculating teleseismic corrections local multiscale investigations developing 3-D