Dear all,
i started to work with specfem2d and i would like to know, if geometrical attenuation is considered by default? I am simulating a Point source at the Surface and want to see the damping of the Rayleigh waves due to Quality factor Qkappa and Qs, and due to geometrical spreading. But i can not find any comment About the geometrical spreading.
Anybody?
Thanks a lot.
Best,
Fabian
Dear Fabian,
specfem2d is a 2D wave propagation code. In 2D wave propagation, surface waves do not have geometrical spreading, because their wavefront is not an expanding circle.
Pablo Ampuero
Thanks a lot for your fast response.
I was just wondering if there is an option in SPECFEM2D to “simulate” the geometrical spreading, even for surface waves.
But it seems that i have to switch to the 3D version.
Best,
Fabian
Dear all,
Just a small remark. It is not uncommon to apply corrections on field seismograms (or records simulated with a 3D propagator) to make it more comparable to records simulated in a 2D world. For this, you can multiply your 3D trace by sqrt(t) and convolve with 1/sqrt(t) to reduce amplitude and phase differences (Crase et al., 1990). The correction is crude and suppose to work well for acoustic medium, but I personally found it effective for surface waves too. Some studies suggest more accurate corrections, e.g. Wapenaar et al. (1992), and Shafer et al. (2014) specifically for surface waves.
Best,
Dmitry