Everything you need to know about a Lahar

DoC have confirmed a moderate lahar is underway, after alarms were activated on Mt Ruapehu's crater lake today.

But what is a lahar - is it the same as a volcano? What causes them, and, more importantly, how prepared are we?

Here is a series of previous stories the Herald has done analysing a lahar from Ruapehu.

PHOTOS: Scientists polish up crisis threat for lahar

Lahar alert rises

Crater under surveillance

First testing of the lahar alarm system, from 2004

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