Executive Summary
New Zealand has a number of volcanoes each with its own eruptive characteristics. While the majority are considered dormant rather than extinct, they can be expected to produce eruptions at some indeterminate time in the future.
Volcanic eruptions will produce a number of hazards, some of which will make their effect felt hundreds of kilometres distance from the volcano. Volcanic planning differs from planning for most other hazards such as floods and drought which are generally predictable in their extent, have a short term warning period, and be of short duration. A volcanic event can build up over weeks to years and be unpredictable in its probable course and timing.
The areas at risk from volcanic activity encompass a large agricultural productive area including most of the North Island with significant areas of dairy, meat and fibre, horticulture and production forestry. Intensive farming is young relative to volcanic activity and there is little historic data on the effects of ash showers on land farmed intensively for agricultural production. Where volcanic eruptions have affected agricultural land, the depth of ash have all been at less than 50mm in recent history. Much of the suggested impacts are conjecture and extrapolations of impacts from lesser ash depths such as Mt St Helens, Mt Ruapehu and Hekla. Given New Zealand's exposure to volcanoes, and the importance of agriculture to the economy, it is appropriate to invest in more research on simulating ash showers to determine the actual effects and methods for rehabilitating the land.
The effect on pastures and livestock will vary depending on the:
- ash type
- consistency and depth of ash deposited
- chemical nature of ash and poisonous aerosols attached to the ash
- amount of rainfall immediately following any ashfall
- wind direction
- metabolic and nutritional demands of the livestock at the time
- age of livestock
- pasture length
Generally one could expect rehabilitation of land from ash falls of up to 100mm but it is difficult to foresee a quick recovery from deposits of over 500mm. However even ash falls of less than 5mm can result in significant impacts for livestock enterprises if the ash is high in chemicals such as fluorine.
The impact of ash showers on horticulture can be considerable with both physical and chemical effects. Even light rates of ash at critical times can reduce crop performance significantly. In addition, light ashfalls can affect either predator pests to increase pest management problems or the dust can affect bees reducing crop pollination.
The impact of volcanic activity on plantation forestry can also be significant from burial, breakage and fire. The infrastructure can also be damaged complicating the response to the direct effects on the forest. For example, if waterways and water sources are contaminated by ash, then pumping systems to control forest fires may not be effective.
The major policy issues for responding to volcanic events as identified following the Ruapehu eruptions of 1995 and 1996 were:
- Inadequately defined and co-ordinated roles.
- Poor communication between agencies who normally have little contact with one another. Differences in operating structures, procedures, terminology and technology compounds this difficulty.
- Resource constraints. The decision not to declare a state of civil defence emergency reduced the available financial resources.
- Plans based on untested assumptions - i.e. some organisations expected the Ministry of Civil Defence to co-ordinate the event but the lack of declaration resulted in inconsistency between their planning and the real event.
The issue of communication resulted in 50% of respondents identifying that there was either insufficient information and/or information was difficult to get hold of.
The lack of trained personnel was also cited as an issue by over a third of respondents. Training is seldom a high priority given the low frequency of event.
Management was also an issue, particularly relying on established decision making structures used for routine activities that may not be suitable for crisis management.
Media problems were reported by 43% of organisations. World wide media interest created significant demands.
This highlighted the need for:
- Better networks among the players with more simulations, and exercises to identify and resolve co-ordination problems should be a priority with readiness programmes. There was evidence that the second volcanic eruption was better managed because of the experiences of the first one.
- A nationally co-ordinated effort would certainly place less demands on national resources such as the Crown Research Institute IGNS who provide the technical expertise to local emergency management organisations.
- Funding is a major issue for territorial authorities. The costs associated with low level events that are not declared can be very high relative to annual rateable income.
The institution framework that is necessary to manage a volcanic eruption emergency will need to give priority to:
- Managing networks and resolving co-ordination problems.
- Providing information to rural people to enable them to manage themselves given that most resources will be targeted to higher urban priorities.
- Managing media interest during the event.
- Maintaining institutional memory and taking account of ongoing restructuring in rural communities, and that assets and resources currently available may not be there for the next event.
There would appear to be knowledge gaps on the recovery from volcanic events that should receive funding from the Public Good Science Fund and there is probably information that could be made available to those responsible for emergency management. This updating would need to be ongoing due to staff turnover and change.
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