Vulcanism

Lesson 3: The Tongariro Volcanic Centre

Mount Ruapehu, 1995. Shaky Beginnings (Bryan Bruce Productions, 1999)

Key Content

• Landscape modification through denudation of the TVC.
• Crater Lake on Ruapehu and the lahar threat.
• Human use of the TVC.
• Hazards to humans in the TVC.

Learning Outcomes

Students will be able to:

• Locate the TVC and its major landscape features on a map.
• Describe how the TVC has been modified by geological and climatic forces over time.
• Outline how humans use the TVC.
• Discuss the hazards to humans in the TVC.
• Use terminology correctly (eg, denudation, andesite volcanoes, lahar, etc.).

Relevant Film Archive Footage and Key Questions

7. Mt Ngauruhoe - Weekly Review 349

Mt Ngauruhoe. Weekly Review 349 (1948)

Think about the effects of an eruption on vegetation and soil. Vegetation and soil processes are closely related to and interact with the climate. Climate has a huge impact upon the modification of these volcanoes (external denudation agents of ice, wind, water, heat).

a. What do you know about the type of vegetation and climate in the TVC?
There are very distinct vegetation stratification zones ranging from tussock and beech forest on the lower slopes to scrub, alpine plants, lichens and moss higher up as the climate becomes harsher.

b. What is the popular walking track at the base of Mt. Ngauruhoe?
Tongariro Crossing. Many students will have done this walk either recreationally or as part of their Vulcanism field trip.

8. Mt Ruapehu - Weekly Review 191

Weekly Review 191 (1945)

The crater lake on Ruapehu is normally 0 degrees Centigrade. The first sign of an impending eruption is an increase in temperature. By the end of 1994 (the year before the 1995 eruption), the lake was 15 degrees Centigrade.

The Ruapehu crater lake dam burst on 18 March 2007, sending a lahar down a predicted path. All warning systems worked, there were no injuries or loss of life, and relatively minimal property damage.

a. What would be the effect of the crater lake dam giving way?
Potential for some serious lahar damage.

b. Should humans intervene to drain the lake before it gives way naturally?

9. Mt Ruapehu - Weekly Review 211

Weekly Review (1945)

Notice that there is no crater lake.

In 1945 skiing and other mountain activities seemed to carry on despite the eruption. During the 1995/96 eruptions the ski fields were effectively closed for two seasons.

Less people on the mountain the less risk from the hazard – more people the greater the risk.

a. What sort of risks are there to humans life, property and infrastructure etc from Ruapehu?

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