軽石粒と火山ガラス片の移動およびベッドフォーム形成条件に関する水路実験(予報)

We preliminaly studied volcaniclastic particle movement in an experimental flume．Experimental particles were obtained from the Pliocene Ohta tephra in central Japan．Average densities of glass particles and pumice grains are 2.25 g/cm^3 and 1.15g/cm^3，respectively．Average grain diameter of them are 0.077mm and 2.8mm，
respectively．We carried out five experimental runs，of which two were using with pumice grains，one with glass particles，one with mixed grains of pumice grains and glass particles，and one with mixed grains of pumice grains and sand-sized quartz grains．Results indicate that the entrainment of volcaniclastics in this experimental study is promoted at higher stream power than for the corresponding smooth spherical grains．Considering the terminal settling velocity of these volcaniclastics，these volcaniclastics show wider velocity range of transportation．Bedforms in mixed grains of pumice grains and glass particles could be controlled mainly by the dominant particles on the flume．