A lava flow is molten rock ( lava) which has flowed over the earths surface from a volcanic vent. Basaltic lavas can flow at speedsf 40 k/hr or 30mph in a lava channel or tube.Andesite in comparison is more viscous and only flows at few Km/hr.Hawaiian lava flows are world famous as they show rivers of running basaltic lava. In the picture lava is flowing into the sea in Hawaii.
Basalt is a mafic lava and contains between 45% and 52% silica and erupts at temperatures of 950+C.Andesite and dacite are intermediate lavas with 52%-63% silica and erupt at about. Rhyolite is a felsic lava with more than 63% silica unlike most felsic lava which erupt/extrude at 700C, rhyolite can erupt at 950C.There are several factors which control the fluidity of a lava flow.
1. Type of lava : can form lava flows, but generally the less silica in lava ie basalt the further and faster it will flow
2. Rate of lava production from the effuive eruption
5. Thickness of flow or channeling.