Why are pyroclastic flows so deadly

Gravity tries to play spoilsport — like it always does — by pulling the heavier particles down, but it is beaten for pace.

The gas lubrication process packs the lowest layer with more gas faster than the heavier particles can sink. Augmenting these observations with computer simulations, the researchers were able to substantiate their claim that air lubrication is the principal mechanism that ensures pyroclastic flows can move so fast.

The importance of studies like this is apparent in their applications, especially in disaster mitigation. While there might not be a completely effective way to protect people against a pyroclastic flow, knowing how it works can allow officials to assess risk more accurately and design better evacuation protocols. A paper published almost 25 years ago reached a similar conclusion: that even a medium-scale eruption of Mount Vesuvius, Italy, could potentially destroy everything in a 7-km radius around it, including a population of one million as of You must be logged in to post a comment.

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Above this, a thick cloud of ash forms over the fast-moving flow. Such a flow can transform the landscape drastically in a short period of time. Not only does it destroy living material in its path, it often leaves behind a deep layer of solidified lava and thick ash. Pyroclastic flows may result in flooding as streams are blocked or rerouted by the flow.

Floods may also occur when the flow of hot material melts snow and ice, swelling rivers and streams beyond their banks.

A mudflow containing volcanic material, called a lahar , may also form when the rock of the pyroclastic flow mixes with water to become a quickly moving slurry.

Also called a cinder cone. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

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They will best know the preferred format. These fast-flowing currents of rock, ash and hot gas are extremely difficult to study, so researchers in New Zealand created their own. By closely studying pyroclastic flows in their specially-made lab, they identified a very thin layer of gas that helps explain how this volcanic phenomenon moves so fast and can travel so far.

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