A lahar (pronunciation: /ˈlɑːhɑːr/) is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley. Lahars are extremely destructive: they can flow tens of metres per second (22 mph or more), be 140 metres (460 ft) deep, and destroy any structures in their path. Notable lahars include those at Mount Pinatubo and Nevado del Ruiz, the latter of which killed thousands of people. The word lahar is the Javanese term for "flowing lava".