H. M.-D. thanks H. Fang, D. Forsyth, R. G. Green, A. Holt, V. Levin, C. Yu and especially L. Royden for helpful discussions, and to Schlumberger for a scholarship. He is also grateful to V. Levin and S. Roecker for making all seismo-grams from the Y2 network freely available through the IRIS Data Management Centre. We also thank three anonymous reviewers for thorough, constructive reviews. Data were processed using ObsPy. All figures were prepared using Matplotlib, alongside the Cartopy library for mapping.
Peer reviewed
Postprint