On an inverse boundary problem in elastodynamics

We study the simultaneous identification of the Lamé parameters $\lambda$ and $\mu$ in three-dimensional static isotropic elasticity. For smooth coefficients, we establish uniqueness from the full Dirichlet-to-Neumann map when $\mu$ is axisymmetric, admits a multiplicative or additive separation on a product domain, or is quasianalytic in one fixed direction. These results require neither smallness of $\mathrm{\nabla }\mu$ nor real analyticity of the coefficients, and impose no corresponding structural condition on $\lambda$. In the axisymmetric and separated cases, partial boundary data suffice to determine $\mu$.