  We report here atomic force microscopy experiments designed to uncover the
nature of failure mechanisms occuring within the process zone at the tip of a
crack propagating into a silica glass specimen under stress corrosion. The
crack propagates through the growth and coalescence of nanoscale damage spots.
This cavitation process is shown to be the key mechanism responsible for damage
spreading within the process zone. The possible origin of the nucleation of
cavities, as well as the implications on the selection of both the cavity size
at coalescence and the process zone extension are finally discussed.
