What is Cold Lava?

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Mt. Kanlaon Natural Park on Negros Island, Philippines, witnessed rivers of cold lava following an explosive eruption recently.

About Cold Lava:

  • Called “lahar” in Indonesian, cold lava is a phenomenon that occurs when rain mixes with volcanic materials like ash, sand, and pebbles.
  • The mixture forms a concrete-like substance that destroys everything in its path.
  • Rain can carry cold lava down the slopes of a volcano during an eruption and into the paths of nearby towns or villages. 
  • Unlike traditional lava flows, which move slowly and give residents time to evacuate, cold lava can advance rapidly, at a speed of hundreds of kilometres per hour, and spread as far away as 60 km from the volcano.
  • One of the defining characteristics of cold lava is its ability to pick up additional debris and sediment as it travels downhill.
    • This mixture can rapidly increase in volume and destructive potential, transforming from a relatively innocuous flow into a powerful force.
  • It is considered more destructive and deadlier compared to regular lava flows.
    • Its high density and abrasive nature mean that it can cause significant damage to buildings, bridges, and roads, posing a serious threat to human life and property.
  • Cold lava remains hot internally due to chemical reactions within the volcanic material, but its external appearance and behaviour are more akin to wet concrete.
  • While it is commonly associated with volcanic eruptions, lahars can also occur when no eruption takes place.

Sometimes, heavy rainfall or snowfall can easily erode and transport fine-grained, loose volcanic sediment and form a slurry, especially if vegetation has not had time to grow back on recent volcanic deposits.

Q1: What is Lava?

Lava is hot, liquefied rock that flows from a volcano or other opening in the surface of Earth. When the liquid rock is still underground it is known as magma. Igneous rock is formed when lava cools and hardens.

Source: Video Shows Rivers Of Cold Lava After Volcanic Eruption In Philippines