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ABC Learn

Video Library Beta

ABC video clips sourced for the Australian curriculum in partnership with Education Services Australia

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Video Clip
Mt Ruapehu [2:56]
ABC Catalyst
20th May 2010
Scientists study lahar flows, 2010
Download Clip [11.00 MB]
Learning Area
Geography, Science
Science as a human endeavour, Science understanding, Earth and beyond

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This clip from the ABC science program Catalyst (2010) looks at the latest scientific enquiry into the effects of lahar flows, flows of water and sediment. Paul Willis presents the work of New Zealand volcanologists conducting research at Mount Ruapehu, a volcano that has had a history of devastating lahar flows. Images of the train wreckage caused by the flow in 1953 are included. Scientists featured are volcanologist Dr Shane Cronin, Professor of Earth Sciences at Massey University, and Dr Gill Jolly, Volcanology Section Manager at GNS Science.

Educational Value

This clip is a valuable resource for exploring sudden geological changes and the ways that scientific understanding can assist in natural disaster management. It explains how lahar flows (also called lahars) occur and shows the consequences of such flows, including the threats to human life. The clip also shows how scientists can monitor a volcano for signs of impending eruption.

The clip shows Mt Ruapehu during an eruption, ejecting ash and other pyroclastic material such as rocks. It also shows the crater lake responsible for this volcano's lahars. When the wall of the lake collapses, water rushes downhill carrying ash, mud and rocks for large distances. The 1953 lahar took a little over two hours to travel the 38 km to the Tangiwai bridge shown in the clip.

The clip attempts to give an idea of the scale of changes produced by geological events such as lahars. Dr Cronin explains that the 1953 lahar was relatively small, and that earlier flow events had covered much greater areas. New Zealand sits on a boundary between tectonic plates, and all its landscapes owe their origin to volcanic and earthquake activity from plate movements.

Since the 1953 lahar, a system has been set in place to monitor the activity of Mt Ruapehu. Dr Jolly explains how this involves measuring seismic vibrations, changes in ground level, and the composition of gases emitted from the volcano's vents. The water level in the crater lake is also monitored to detect imminent collapse of the lake wall in the absence of an eruption. This system was effective in preventing deaths from a lahar in 2007.

More videos like this in:

Natural and man-made impacts on ecosystems

Related information:

› Catalyst story archive with story transcript and links

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