Chinmaya IAS Academy – Current Affairs Chinmaya IAS Academy – Current Affairs
Cold lava, also known as lahar (Indonesian and Tagalog), is a fast-moving, mudflow-like slurry of volcanic debris and water. It rushes down the slopes of volcanoes, often following river valleys, and can be extremely destructive.
Formation
Cold lava formation can be triggered by several mechanisms:
- Heavy Rainfall: When intense rain falls on loose volcanic material (ash, tephra, rock fragments) on a volcano’s slopes, it can saturate the material and trigger a lahar.
- Snow and Ice Melt: Melting snow and ice on a volcano, caused by volcanic heat or rising temperatures, can combine with volcanic debris to form a lahar.
- Eruption-induced Events: Volcanic eruptions can directly generate lahars by:
- Melting snow and ice on the volcano.
- Mobilizing existing volcanic material with pyroclastic flows (superheated gas, ash, and rock fragments).
- Causing lahars through lake breakout floods (volcanic landslides displacing water bodies).
Properties
- Temperature: While called “cold lava,” lahars can vary in temperature. They can be hot (near boiling) if formed from interaction with hot volcanic materials, or cold if primarily derived from melting snow or rainfall.
- Consistency: The consistency of a lahar can range from watery mud to a thick, dense slurry, depending on the water content and debris size.
- Speed: Lahars can travel at high speeds (up to 75-80 km/hr or more) due to their fluid nature and steep slopes on volcanoes.
- Destructive Power: Lahars are highly destructive due to their volume, speed, and ability to bury and crush entire structures. They can also devastate infrastructure and cause widespread mudflows.
How Cold Lava Differs from Normal Lava
- Temperature: Normal lava is extremely hot (800°C to 1200°C) compared to the variable temperature of lahars.
- Composition: Normal lava is molten rock, while lahar is a mix of water and volcanic debris.
- Movement: Lava flows slowly due to its high viscosity, whereas lahars move rapidly due to their fluid nature.
- Impact: Normal lava primarily affects areas directly in its path, while lahars can travel long distances and cover vast areas, causing widespread destruction.
