Feature request: modelling attenuation based on teleseismic distance from source

[medlin01GA]

It would be nice to be able to be able to synthesize waveforms with modelled frequency dependent attenuation based on teleseismic distance from source.

If there is an idealization by which this could be fairly easily done myself, I would appreciate to know how I could do it.

[paudetseis]

Thanks for your query. In theory this is feasible in the matrix propagator approach adopted here. For isotropic media, it would be possible to implement complex-valued elastic constants to model Qs and Qp. It is unclear to me how to proceed for anisotropic media; I suspect anisotropic Q would be required.

One limitation of our approach is that it assumes a near-vertically-propagating plane wave incident upon a stack of layers from below. Any attenuation between the (virtual and impulsive) source and the stack cannot be modelled by the matrix propagator approach in this case (since it happens outside of the modelled volume), although the effect of such attenuation on waveforms could still be modelled as an integrated path effect using a known global layered model (e.g., iasp91, prem, etc.).

The answer can probably be found in the book by Kennett (Seismic Wave Propagation in Stratified Media), but I must say this would be a rather extensive modification to the code and I am personally not willing to undertake this at this time. It's more like including additional theory than simply adding a new feature to the code. Feel free to take a stab at it and I would appreciate to follow your progress if you do.