In a study of global body wave coda, it could be shown that PREM-seismograms (shaded) can model global envelopes (full colors) for several hours down to periods of 2 seconds. The results have been part of a study just published in Geophysical Research Letters and would not have been possible without AxiSEM and much less convenient without Instaseis.
http://onlinelibrary.wiley.com/doi/10.1002/2015GL065108/full
