Some remarks on the Biot system of equations describing wave propagation in a porous medium

The symmetric form of poroelasticity dynamic equations in terms of velocities, stresses and pressure

“…In the isotropic case, a di erence of the linearized system of equations (1) from well-known equations of the FrenkelBiot type [6,7], is described by the three elastic constants [4,5]. These elastic parameters in a one-to-one manner are expressed by the three velocities (c t , cp , cp ) of elastic oscillations [8], [9], [10]:…”