  We experimentally study the crack formation and decompaction-wave propagating
in a vibrated powder bed consisting of glass beads of 5 {\mu}m in diameter. The
vibrated powder bed exhibits three distinct phases depending on the vibration
conditions: consolidation (CS), static fracture (SF), and dynamic fracture
(DF). Particularly, we found an upward wave propagation in the DF regime when
the powder bed is strongly vibrated. As a remarkable feature, we found that in
fine cohesive powders, the decompaction-wave propagation speed normalized to
gravitational speed is independent of the shaking strength. This result implies
that the wave propagation speed is governed by the balance between gravity and
cohesion effect rather than vibration strength. We also explore the
universality of wave propagation phenomenon in coarser and low-density granular
powders.
