Lahars

• Lahar is an Indonesian word used to describe a mudflow which occurs following a volcanic eruption.
• Lahars can occur following the eruption of a snow capped volcano.
• Snow and ice melt and join with mud from the volcano slopes along with lava and ash from an erupting volcano.
• Lahars can also be triggered by the torrential rain which often follows a volcanic eruption.
• The volcanic eruption creates a hot river of mud which flows down the slopes of the volcano and may travel many kilometres often at great speeds.
• Lahars can have devastating effects for nearby towns and villages.
• In 1985 the volcano Nevada Del Ruiz erupted in Colombia.
• The 1985 Colombian Volcanic eruption ash and pumice immediately began to rain down on the nearby town of Armero and people were ordered to evacuate. The evacuation was called off once the ash stopped falling.
• Snow on the volcano melted to create an enormous lahar which travelled down the side of the volcano at speeds of 60km per hour.
• Bad weather meant residents of the town were unable to see the volcano clearly.
• Less than two hours after the eruption, the lahar hit the town.
• The Lahar engulfed the town of Armero killing 20,000 of its 29,000 inhabitants.
• Damage from the Lahar was estimated at $1 billion.
• It is widely believed that this event could have been avoided as Nevado del Ruiz had experienced several earthquakes and minor eruptions in the previous year.
• However Colombia lacked the experts and technology to monitor the volcano.