Definition

Noun: A lahar is a destructive, fast-moving flow of water, volcanic ash, rock fragments, and mud down the slopes of a volcano. It behaves like a fluid avalanche and is often triggered by heavy rainfall on loose volcanic deposits or by volcanic activity melting snow and ice.

Usage

The word lahar is used to describe a specific and dangerous geological phenomenon associated with volcanoes. It is a technical term common in geology, volcanology, and disaster reporting.

Examples

• The eruption melted the glacier, generating a massive lahar that buried villages in its path.
• Scientists monitor rainfall near the volcano to warn of potential lahar threats.
• The valley's topography shows evidence of ancient lahars from previous eruptions.

Advanced Usage

• Lahars can travel many kilometers from their source volcano, following river valleys and causing devastation far from the eruption site.
• Unlike lava flows, lahars can occur even when a volcano is not actively erupting, if heavy rain mobilizes unstable ash deposits.

Variants and Related Words

• Debris flow: A more general term for a fast-moving slurry of mud, water, and rock; a lahar is a specific type of volcanic debris flow.
• Mudflow: A flow of water and fine-grained sediment; a lahar often contains coarser material like boulders.

Synonyms

• Volcanic mudflow
• Debris avalanche (in a volcanic context)

Related Phrases/Idioms

There are no common idioms or phrasal verbs using the specific term lahar. It is used literally to describe the geological event.

Noun

1. an avalanche of volcanic water and mud down the slopes of a volcano