Haned, A., E. Stutzmann, M. Schimmel, S. Kiselev, A. Davaille, and A. Yelles-Chaouche (2016), Global tomography using seismic hum, Geophysical Journal International, 204(2), 1222-1236, doi: 10.1093/gji/ggv516.
We present a new upper-mantle tomographic model derived solely from hum seismic data. Phase correlograms between station pairs are computed to extract phase-coherent signals. Correlograms are then stacked using the time–frequency phase-weighted stack method to build-up empirical Green's functions. Group velocities and uncertainties are measured in the wide period band of 30–250 s, following a resampling approach. Less data are required to extract reliable group velocities at short periods than at long periods, and 2 yr of data are necessary to measure reliable group velocities for the entire period band. Group velocities are first regionalized and then inverted versus depth using a simulated annealing method in which the number and shape of splines that describes the S-wave velocity model are variable. The new S-wave velocity tomographic model is well correlated with models derived from earthquakes in most areas, although in India, the Dharwar craton is shallower than in other published models.