Mr Blunt, who spent two hours talking to staff and inmates at Ford prison near Arundel, West Sussex, following the New Year's Day rampage, said the Prison Service inquiry will need to consider whether the violence could be repeated.
The suitability of the inmates being held at Ford, as well as the prisoners' access to alcohol, will also need to be examined in the wake of the violence which saw communal areas of the jail destroyed, Mr Blunt said.
About 40 prisoners turned violent in the early hours after officers attempted to breathalyse them for contraband alcohol.
The rioters set light to buildings during the night and again at lunchtime, causing extensive damage to six accommodation blocks, a gym, mail room and snooker and pool rooms.
Asked if having just two trained officers and four support staff for the 496 prisoners was appropriate, Mr Blunt said: "It's obviously an issue that will be part of the inquiry and an issue around the policy of staffing levels at all open prisons."
He went on: "One of the issues will be about whether there are particular circumstances at Ford – to examine whether the staffing policies are appropriate at Ford compared to other open prisons.
"What we need to remember was that the incident was unprecedented. If something happens that's unprecedented, we've got to examine what the likelihood is of it recurring."
Mr Blunt also revealed that staffing was at the minimum level after one support officer called in sick at short notice and was not replaced.
The inquiry will also look at whether inappropriate prisoners have been sent to the open jail.