Elastic Properties of Methane Hydrate Studied by High-Pressure Brillouin Spectroscopy.

Abstract

The elastic properties of structure I (sI) methane hydrate (MH) determined by high-pressure Brillouin spectroscopy up to 0.6 GPa at 23℃ are reviewed by comparing them with those of ice-Ih. The pressure dependence of adiabatic elastic moduli of sI-MH is similar to that of ice-Ih except for C 11. Elastic moduli and bulk modulus indicate that sI-MH is slightly more compressive than ice-Ih, and acoustic velocities show nearly isotropic behaviors with respect to the crystal orientation. The C 44 of sI-MH is less sensitive to pressure and smaller than C 11 and C 12 , which implies the sI-MH is becoming less stable against the shear stress under high pressures. These results are useful to investigate the dynamic stability and the estimated amount of MH in the deep-sea sediments.