What a beautiful spectacle! As we traveled down the coast of Chile we encountered several large glaciers like the one in this photo. It amazed me to see that all were a deep blue in colour since ice is normally white to colorless like ice cubes in a glass. Even the chunks of ice that have calved and are floating away from the glacier-water interface are blue as shown in the other picture. The blue colour is caused by compaction of the snow as it accumulates inland and begins its journey to the sea. In this compacted condition together with included rock dust ground in from the rock strata below the red light end of the visible light spectrum (think of a rainbow) is absorbed leaving the blue light which is consequently what you see.