I can feel it, coming in the air tonight
On August 6, one of New Zealand’s volcanos erupted for the first time since the 1880’s. The volcanic complex, known as Mt Tongariro became active at about 11:50pm then flung rock up to a kilometre and pumped out an ash plume which travelled across the North Island.
Of course, being a safe distance away from the volcano, I found this all very exciting, having been hiking in the area only a few weeks before the eruption happened. It’s all very exciting for scientists as well, as they continue to study the effects of the eruption.
The most notable effect is the ash plume, which can be seen by satellite.
The plume contains a number of substances that have spin-off effects for people around New Zealand. One such substance is obsidian, or volcanic glass. Obsidian can get into airplane turbines and, with enough heat, be melted and subsequently cause engines to stall. For this reason, a number of flights within New Zealand were halted for a short period following the eruption.
Secondly, gases such as sulfur dioxide and carbon dioxide continue to be pumped out of Tongariro, even though the activity around the complex has died down. While not at high enough levels to cause concern, people have been complaining about the smell (think boiled eggs).
A kind of cool effect of the eruption is that new lakes have been formed around the Tongariro complex. A stream that flows from the crater where the eruption occured has now been dammed, resulting in three new lakes. If they’re anything as beautiful as some of the existing lakes in the area, I’m sure this will be a draw-card for trampers from around the world.
The visable signs of the eruption have also allowed scientists to better understand how the eruption occured. At first, it was thought that it was a hydro-thermal eruption but now they believe it was phreatic. This is when water is suddenly turned to steam by coming in contact with heat from magma. The steam expands the surrounding rock, causing it to be blasted out of the volcano. Hydro-thermal eruptions are similar, in that they’re caused by water turning to steam but different in that this process is not due to coming in contact with magma. Rather, it occurs by a decrease in fluid pressure. Scientists were able to determine that it was a phreatic eruption due to magma gas being present in the ash cloud as well as in readings taken near the volcano.