The velocity of seismic waves and the electrical conductivity of the oceanic crust and mantle at mid-ocean ridges depend on how melt is distributed around mineral grains. The strength of the mantle also depends how much melt is present, so flow of the mantle is strongly dependent on the amount of melt. The investigators want to examine several aspects of melt distribution with laboratory experiments on mantle rocks. The experiments will determine how the strength of the rocks depends on the presence of water, and temperature, and strain. They will also determine how melt is distributed in the rocks. The results of these experiments will be applied to measurements of seismic wave velocities and electrical conductivity that are being undertaken on a mid ocean ridge.