Experimental study of gas-fluidized granular flows with implications for pyroclastic flow emplacement

Experiments have been carried out on initially gas-aerated and gas-fluidized granular flows propagating into a horizontal channel. After lateral acceleration following release of the originally fluidized bed, two contrasting flow behaviors were observed, which reflected the degree of initial fluidization and the grain size. Initial fluidization disrupts the interparticle contact network, which controls internal friction of the static bed. The flow regime then depends on the timescale needed to reestablish a strong contact network, and this time increases as the grain size decreases. Initially aerated and fluidized flows of coarse particles (>approximate to100 mum) and initially aerated flows of fine particles (