MAF forecasts impacts of volcanic eruption on primary sectors

10 May 1999

A report on the impact a volcanic eruption could have on New Zealand's primary sector has been released by the Ministry of Agriculture and Forestry.

The report's conclusions have been discussed in seminars for district and regional council staff, farmers, foresters and horticulture and agricultural producers in Rotorua, Hamilton, Napier and Palmerston North.

New Zealand remains one of the most active volcanic regions in the world, and a reminder of the potential impact of a volcanic eruption on agriculture came in October 1995 and June 1996 when Mount Ruapehu erupted, resulting in 10mm ash deposits close to the mountain, and 1-3mm deposits in the furthest reaches.

Given New Zealand's exposure to volcanoes, and the importance of agriculture and forestry to the economy, most eruption scenarios are likely to have a significant impact on the sector and consequences on the nation as a whole. Mount Ruapehu's 1995/96 eruptions, although minor, did disrupt farming.

The biggest loss was $250,000 damage to a Gisborne cauliflower crop 250kms downwind from Mount Ruapehu), and the death from fluorine poisoning of 2000 ewes as a result of eating ash-affected pastures. The Department of Conservation also reported a number of wild deer deaths in the Kaimanawa Ranges, and farmers reported animals put off their feed by ash deposits.

MAF Senior Policy Analyst Phil Journeaux said that the document, Impact of a Volcanic Eruption on Agriculture and Forestry in New Zealand, should be of interest to anyone involved in primary production within the vicinity of possible ash fall from a New Zealand volcano. Areas at risk from volcanic activity encompass large productive dairy, deer, sheep, beef and arable areas across virtually all of the North Island.

MAF has a responsibility to report to Government on the impacts of adverse climatic events and natural disasters affecting the primary sector, likely to require assistance after the event. The report lays out a national contingency plan for volcanic eruptions to be taken by Government, regional councils, territorial authorities, and other agencies with civil defence responsibilities, in preparation for and response to volcanic eruptions.

As smaller eruptions occur more frequently than larger eruptions, the plan shows appropriate responses according to predicted scale or expected impact. This can range from a few centimetres of ash fall to salvaging a buried forest.

During the Ruapehu eruptions, the Ministry distributed its publication, Volcanic Alert to assist farmers and growers in their decision making. The latest report brings together the expertise of agriculturalists, horticulturists, volcanologists and foresters to examine the impact a range of eruption scenarios could have on the agriculture and forestry sectors.

A volcanic event can build up over weeks to years and be unpredictable in its course and timing. Ash fall can be deposited hundreds or thousands of kilometres from the source, making volcanic ash the product most likely to affect the largest area, and the most people during an eruption.

For example, the volcanic affects on pastures and livestock varies depending on the type, consistency, depth and chemical composition of the ash deposited, the amount of rainfall immediately following any ash fall, wind direction, metabolic and nutritional demands of the livestock at the time, age of the livestock, and pasture length.

For further information contact:
Phil Journeaux, MAF Policy, Hamilton, ph: 07 856 2832,
or visit the MAF website to read the document



Last Updated: 10 September 2010

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