Janine Krippner
“Volcano spewing smoke” is my least favourite volcano headline phrase.
Why? While the term ‘spewing’ is not my favourite, volcanoes just do not emit smoke (excluding when hot volcanic rocks and lava flows set things on fire). Why do we care here in the Waipā? We see volcanoes erupting on the news and it’s always fun to know what we are looking at, but more importantly, one day we could experience volcanic ash here again.
It is the most widespread eruption product in terms of how far it travels from the volcano, and where it goes is a result of the type and size of the eruption (how much ash is erupted and how high it goes into the atmosphere), and where the wind is blowing it. As we know, we have variable wind directions in New Zealand. As the ash plume is blown away by these winds, the ash particles settle out across the landscape.
This forms an ash deposit that can be millimetres to metres thick, getting thinner away from the vent. Flights can be cancelled across countries and even oceans away from a volcano that you probably hadn’t heard of, and may not be able to pronounce, can you say “Eyjafjallajökull” after its 2010 eruption? I hear being in a plane that flies through an ash plume is a zero out of five stars experience when the engines stop.
Some movies show volcanic ash as this fluffy grey stuff that floats down towards us just like ash out of a fireplace. This is not at all realistic. Volcanic ash is pulverized magma and solid rock, violently blown apart when gases within magma rapidly expand like a bottle of soda after you shake it up. Volcanic ash is defined as any rock bits coming out of a volcano that are less than two millimetres in size. Rock bits 2-64 mm are lapilli, larger than that is either a solid “block” or a more fluid “bomb”.
While ash from a bush fire causes its own problems, issues arising from volcanic ash are very different. You can probably imagine that bits of rock get very heavy as it accumulates. Have you picked up a bucket of sand lately? It’s about the same, and it’s even heavier if you also have rainfall. It is also abrasive with its sharp edges. When magma cools quickly it actually forms rock that is made up of glass and crystals. Trust me, do not wipe the stuff off your glasses or any other glass surface using a cloth. Use water.
Ash can impact power supplies, water supplies, road networks (reducing visibility and making a slippery surface), communications networks, air conditioning systems, computer systems, vehicles… the list goes on and some of these can cause issues far beyond the area impacted by the eruption.
It can also wreak havoc on agriculture, I will expand on this another time for our farming community. Thankfully, work is already well underway in Aotearoa to understand these impacts and how our systems could be impacted, and what we can do about them. As with any hazard, being prepared before it happens saves us a lot of money and time.
