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Be Prepared: Volcanic Ash Fall

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Ash fall is the most likely volcanic hazard. This will only happen if the wind blows the ash cloud your way. Knowing what to do before you have to do it is very important.

Eruptions from volcanoes like Ruapehu, Ngauruhoe and White Island will most likely produce light ash falls (less than 50 mm) thick.

Listed below is general information about protecting yourself and your home from the effects of ashfall. The effects on infrastructure can be very damaging. A series of specialist posters has been prepared for infrastructure and urban managers.

What to do during an ash fall

  • Stay indoors
  • Close windows and doors. Stop ash entering the building
  • Do not run air-conditioning or clothes dryers
  • Listen to the radio for advice and information
  • If outside seek shelter; use a mask or handkerchief for breathing. Wear protective clothing especially if working in the ash fall, and goggles to protect the eyes.
  • If possible do not drive, park your car under-cover or cover it
  • If you must drive, drive slowly as ash fall will reduce visibility. You may need to use the car headlights because of the reduced visibility. Do not use the car’s ventilation system. Ash on the road surface can also reduce traction.
  • Do not rush to your child’s school. Schools are responsible for the safety of the children. Schools will notify you of any emergency procedures which are to be taken.
  • Keep pets indoors.
  • Check that livestock have enough food and water. May need to shelter livestock if the fall is heavy.
  • Disconnection of roof-fed water supply is only required when an ash fall is occurring or during the clean up to stop ash entering the storage tanks.
  • If you are uncertain of what to do seek advice from civil defence

How to clean up an ash fall

  • Wetting down ash will form a glue-like material (not easy to remove) and add weight to the ash. The best method is to lightly damp the ash (to prevent it billowing) and to sweep it up. Remember water will be in high demand.
  • Remove ash immediately (before rain if possible) but remember ash particles commonly have sharp broken edges making it a very abrasive material.
  • Clean house roofs first to reduce windblown ash covering cleaned areas or damage to guttering and blocking down-pipes.
  • Place ash in rubbish bags if possible and seal them.
  • Do not dump ash in the storm-water or sewage system.
  • Contact your council for information on the disposal of ash.
  • Prevent further ash entering house by restricting access to the most protected (sheltered) entrance.
  • Vacuum indoor surfaces were possible or use a damp cloth to remove ash. Avoid vigorous rubbing.
  • To remove ash from your car wash with plenty of water. Carry out car maintenance if you have been driving in ash. For example, check/change air filter, oil filter, oil and brake pads in car.
  • Dry ash should be blown off with high pressure air, while wet ash should be cleaned off by hand or with water at high pressure.

Protection against ash fall

  • Ash should be removed from building roofs to avoid collapse which could result in injury to the building occupants. About 100 mm of dry ash could collapse a flat roof. Before ash is to be removed, ensure that storm water systems are sealed to stop ash entering. If possible, sweep ash off in a dry state – the addition of water will turn the ash into mud which can set like concrete. Remove the swept ash to a suitable dumping site. Caution is needed working on roofs.
  • In heavy ash falls, windows and doors may need additional sealing to avoid ash entering the building. Extra care must be taken by people entering buildings to ensure that outer clothing and footwear is removed early to avoid spreading ash throughout the building.
  • All ash removal measures are labour intensive and require constant attention.
  • All types of engines (cars, trucks, aircraft), will require additional filtering with regular changes in order to maintain efficiency. Advice should be sought from manufacturers as to suitable air filter requirements.
  • Careful monitoring of lubricant needs to be conducted. Lubricants may need to be changed at up to four times the normal frequency. Other working parts on vehicles and machinery such as brakes, conveyors and electrical motors need to be dusted or air blasted on a frequent and regular basis to avoid excessive abrasion.
  • Farm and industrial machines such as tractors and diggers, have a greater tolerance to ash, however, additional protective measures will be required for these to continue operating in ashfall conditions.
  • Crops and plants are damaged by volcanic ash which may contain volatile, highly toxic components such as fluorine, hydrogen sulphide and sulphur dioxide. Advice should be sought before consuming food that may have been affected by volcanic deposits.
  • Volcanic gases can have severe effects on plants from wilting outer leaves to killing. Trees laden with ash could collapse or be stripped of their upper and outer limbs.
  • Tank supplies should be disconnected from house roofs whilst ash fall continues and the tank protected. They can be reconnected once ash fall stops and the roof is cleaned.
  • Breathing in small amounts of ash particles infrequently may only cause discomfort rather than pose a health hazard. At higher concentrations, people should avoid ash and fine dust simply by using cloth filters over the mouth and nose.
  • People required to work in ash fall should wear protective clothing, masks and goggles to ensure that ash contact with the body is at a minimum. Prolonged exposure can cause severe irritations and inflammation. Gas marks would be required if toxic gases are detected.
  • Livestock may require additional feed where the ash fall makes grazing difficult. Water supplied must be checked to ensure it is not harmful. Sheltering of livestock in buildings may be required in heavier ash fall areas. Early evacuation of livestock may also need to be undertaken.