Volcanic hazards - Lahars in Indonesia

Lahar is an Indonesian word for volcanic mudflow. There are numerous volcanoes in Indonesia and lahars often occur as a result of water mixing with volcanic ash, mud and boulders. Lahars can move at speeds of 60km/hour and sweep away anything in their paths. Earthquakes also occur as a result of plate tectonics. The town of Franz Josef on South Island, New Zealand, lies on a transform boundary.