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  Council » Policies and Plans » Hazard and catchment management » Risk mitigation plans » Volcanic Risk Mitigation Plan

Volcanic Risk Mitigation Plan

Waikato Regional Council's Volcano Risk Mitigation Plan sets out efficient and effective volcano risk management for the Waikato region. Volcano risk management aims to lessen the effects of volcanic hazards such as eruptions, lahars (mud flows) and ashfall by planning for evacuation (where necessary), response and recovery. Risk mitigation plans define the roles of Environment Waikato, district councils, and the community in managing the impacts of potential natural hazard events.

Photograph of Mount Ruapehu erupting

The Waikato region has more volcanic hazards than any other region in New Zealand. This is because:

  • A large part of the Taupo Volcanic Zone (TVZ) lies within or next to the Waikato region’s boundaries.
  • Our region contains three presently or potentially active volcanic centres -Tongariro, Taupo and Maroa.
  • Many urban areas (for example, Turangi, Taupo, and Tokoroa) lie within the Taupo Volcanic Zone.
  • These are vital lifelines (roading, rail, power supply lines) in the Taupo Volcanic Zone.

Waikato Regional Council's Volcano Risk Mitigation Plan aims to achieve efficient and effective volcano risk management through:

  • clarifiying the volcano management roles and responsibilities of various agencies
  • dealing with the adverse effects of volcanic activity and the management options for minimising them
  • planning for response, recovery, monitoring and review activities.

Find out more about Volcanic Activity.

View or print Waikato Regional Council's Volcano Risk Mitigation Plan from the document below, or order a printed copy of the Plan through our publications pages.

Volcanic Risk Mitigation Plan
(815 kb, 116 seconds to download, 56k modem)  

Table of contents

Table of contents i
Executive Summary iii
Background and explanation v
1 Introduction 1
2 Pre-eruption: mitigation techniques for non-crisis periods 3
  2.1 Geological studies 3
  2.2 Planning   3
  2.3 Scientific alert levels and science alert bulletins 6
  2.4 Monitoring 6
  2.5 Satellite remote sensing 7
3 During an eruption: a description of different volcanic hazards and mitigation measures for those hazards 9
  3.1 Tephra falls  
    3.1.1 People 10
    3.1.2 Agriculture and horticulture 10
    3.1.3 Building structures 13
    3.1.4 Electricity 13
    3.1.5 Water supply 14
    3.1.6 Wastewater networks (stormwater drainage and sanitary sewers) 14
    3.1.7 Sewage treatment plants 14
    3.1.8 Gas 14
    3.1.9 Transportation 14
    3.1.10 Communications 15
    3.1.11 Mechanical, electrical and electronic equipment 15
  3.2 Mitigation measures to tephra fallout 15
    3.2.1 People 15
    3.2.2 Agriculture and horticulture 15
    3.2.3 Building structures 16
    3.2.4 Electricity 16
    3.2.5 Water supply 17
    3.2.6 Wastewater networks (stormwater drainage and sanitary sewers) 17
    3.2.7 Sewage treatment plants 18
    3.2.8 Transportation 18
    3.2.9 Mechanical, electrical and electronic equipment 19
    3.2.10 Ash disposal 19
    3.2.11 Detailed mitigation measures 19
  3.3 Ballistic fallout 20
    3.3.1 Mitigation measures for ballistic fallout 20
  3.4 Lahars 20
    3.4.1 Mitigation measures for lahars 20
  3.5 Pyroclastic flows 22
    3.5.1 Mitigation measures for pyroclastic flows 22
  3.6 Pyroclastic surges 22
    3.6.1 Mitigation measures for pyroclastic surges 22
  3.7 Volcanic blasts 23
    3.7.1 Mitigation measures for volcanic blasts 23
  3.8 Lava flows 23
    3.8.1 Mitigation measures for lava flows 23
  3.9 Debris Avalanches 24
    3.9.1 Mitigation measures for debris avalanches 24
  3.10 Volcanic gases 24
    3.10.1 Mitigation measures for volcanic gases 25
  3.11 Tsunamis and seiches 25
    3.11.1 Mitigation measures for tsunamis and seiches 26
  3.12 Flooding 26
  3.13 Hydrothermal eruptions 26
    3.13.1 Mitigation measures for hydrothermal eruptions 26
  3.14 Volcanic earthquakes 27
    3.14.1 Mitigation measures for volcanic earthquakes 27
  3.15 Electrical discharges 27
    3.15.1 Mitigation measures for electrical discharges 27
  3.16 Other hazards 27
References 29
Appendix I: Scientific Alert Levels (Johnston, 1997a) 37
Appendix II: Detailed mitigation measures 38
Appendix III: 1995-1996 Ruapehu Eruptions Survey 52
Tables 5
Table 1: Educating the public about volcanic hazards (after Gregory 1995; Peterson, 1996; Voight, 1996) 5
Table 2: Impacts on plants and soil from increasing ash thickness (after Folsom, 1986 and Blong, 1984; in Neild et al., in prep) 11
Table 3: Periods of high crop risk from ash (after MAF, 1995; Neild et al., 1998) 12
Table 4: Mitigation measures for volcanic ash and the water supply (after Johnston 1997a, 1997b) 17
Table 5: Number of survey participants involved in each type of business 55
Table 6: How respondents solved or fixed problems caused by Ruapehu eruptions 66
Table 7: Common hints suggested by survey respondents 67
Table 8: Lifestyle adaptations made in response to Ruapehu eruptions 70
Table 9: Range of benefits from the Mount Ruapehu eruptions 72
Table 10: Organisations that respondents turned to for advice or general information during the 1995-1996 Ruapehu eruptions 73
Table 11: Impact of a volcanic eruption from Mount Ruapehu in different seasons 74
Figures 1
Figure 1: Summary of volcanic hazards from a composite cone volcano (after Myers et al., 1997) 1
Figure 2: Volcanic hazard management during non-crisis (pre-eruption) periods (after Johnston and Houghton, 1995) 2
Figure 3: Summary of the applications of remote sensing for volcanology (after Oppenheimer, 1997) 8
Figure 4: Ash from Mount Ruapehu carried by southeasterly winds over Lake Taupo during the 1995-1996 Ruapehu eruptions 9
Figure 5: The interaction of volcanic gases during an eruption (after Johnston, 1997a) 25
Figure 6: An eruption from Mount Ruapehu on 8 July 1996 53
Figure 7: Question 2 – What category do you class your business in? 54
Figure 8: Turnover of businesses that answered the Ruapehu survey (logarithmic scale) 56
Figure 9: The arrangement of zones around Mount Ruapehu 57
Figure 10: Question 6 – Please indicate where your home or business is located 58
Figure 11: Series of graphs looking at the relationship between peoples’ location and how likely they think they would be affected by a future eruption 59
Figure 12: Respondents’ knowledge of what to do during an eruption 61
Figure 13: How did you first learn that there was an eruption occurring from Mount Ruapehu? 63
Figure 14: Location of the respondent versus whether they were affected by the 1995-1996 Ruapehu eruptions 64
Figure 15: Question 19 – Did you suffer any economic loss related to the Ruapehu eruptions? 69
Figure 16: Losses (NZ$) suffered by different types of business (Logarithmic scale) 69
Figure 17: Types of stress suffered as a result of the Ruapehu eruptions 71
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