Silica glasses were repeatedly densified by multiple shock reverberations in stainless-steel capsules. The limit of increase in density was about 2.47 Mg/m3after the first shock loading. Further increase in density was observed after duplicate shock loading, but limited at about 2.55 Mg/m3. Triplicate shock loading was not so effective for the increase in density. The Raman spectra of recovered silica glasses had characteristics of densified silica glass with much higher density. The remarkable one was the enhancement of the line at 605 cm−1called the D2line, which was one of two narrow lines peculiar to the Raman spectrum of silica glass. ©1997 American Institute of Physics.