how fast does pyroclastic flow travel at?

Question: how fast does pyroclastic flow travel at?
- Keywords:
  energy,
  pyroclastic
Asked by heebeejeebee to Alessandro, Angela, Claudia, Marina, Phil on 20 Mar 2013.
- Phillip Wilkinson answered on 20 Mar 2013:
  
  Pyroclastic flow is a specific type of eruption.
  
  Up to 450 mph, its the side of a mountain exploding, so its quite rapid. 😛

Question: how fast does pyroclastic flow travel at?