Fluid basalt flows can extend tens of kilometers from an erupting vent. The leading edges of basalt flows can travel as fast as 10 km/h (6 mph) on steep slopes but they typically advance less than 1 km/h (0.27 m/s or about 1 ft/s) on gentle slopes.
A lava flow moves down the flank of a volcano under the influence of gravity, similar to how water flows downhill through gullies, channels, and valleys. When lava has stopped moving, lava solidifies to form igneous rock.
