Resolving the Undrained Bulk Modulus Controversy—Gassmann (1951) holds, but Brown and Korringa (1975) do not

Recently, Thomsen claimed that Gassmann’s expression for the undrained bulk modulus of microhomogeneous porous media is incorrect and that the Brown and Korringa (BK) formulation for microinhomogeneous systems must supersede it universally. To resolve this controversy, we present a self-contained, rigorous framework rooted strictly in the empirical Terzaghi effective pressure principle and fundamental fluid–solid mass conservation laws. By incorporating porosity perturbation as an independent kinematic variable, this framework—consolidated from a series of papers published over the past fifteen years—demonstrates why neither of Thomsen’s assertions holds. Gassmann’s expression is correct for microhomogeneous media because it honors the solid mass balance equation. Conversely, the physical inconsistency of the BK formulation outside the microhomogeneous limit—stemming from a restriction that violates solid mass continuity.

Lugar: Ciencias de la Tierra, CICESE, Ensenada, México

Fecha: 02-10-2026

Hora: 12:00 pm