Seismic transmission coefficient
= Seismic transmission coefficient
{title2=$T_\sigma=2Z_b/(Z_a+Z_b)$}
The transmitted-to-incident amplitude ratio at an interface, with physical variable specified. At normal incidence, stress amplitudes give $T_\sigma=2Z_b/(Z_a+Z_b)=1+R_\sigma$, while particle velocity gives $T_v=2Z_a/(Z_a+Z_b)=1-R_\sigma$. The transmitted energy fraction is $4Z_aZ_b/(Z_a+Z_b)^2$; amplitude greater than one therefore does not by itself violate <conservation of energy>.