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Volcanic eruptions are infrequent in New Zealand, but they have occurred in recent times, such as the 1995/96 eruption of Mt Ruapehu.
The plains around New Zealand’s volcanoes create productive soils but can also be hazardous in the event of an eruption. If you live and farm in an active volcanic area, there are a number of actions you can take to mitigate and manage your recovery after an eruption.
Volcanic Eruption! Impacts and hazard mitigation for New Zealand’s primary production industries.
On-Farm Adverse Events Recovery Plan for information on how adverse events are classified and the range of assistance available rural communities.
New Zealand is a volcanically active country, and any eruption of even moderate size could have significant implications for the primary sector. This report investigates some of the effects of an eruption and methods for rehabilitating the land.
The effect on pastures and livestock will vary significantly 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, and 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, to breakage and fire.
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.