Pressure dependence of elastic constants (C11, C12, C44) for some sI and sII gas hydrates have been determined by high-pressure Brillouin scattering measurements and their analyses. The values of elastic constants C11 of gas hydrates and their pressure dependences clearly show the differences among gas hydrates, depending on the size and the shape of guest not on the gas hydrate structure. In contrast, the pressure dependence of C44 corresponding to shear stress does not indicate an obvious difference among gas hydrates.
