Tag Archives: Supervolcano

Lake Taupo

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For years a major thing on my bucket list was to swim in a crater lake, which as the name suggests is a body of water formed in a volcanic crater or caldera. Luckily I got to tick this one of when I visited Nicaragua last year and swam in the blissfully warm Apoyo Lagoon, but of course this only appealed to my addictive nature and made me dream about going one better…how about a crater lake formed by a super eruption. When my friend told me she was off travelling for a few months and her first port of call would be New Zealand, I decided she could live my dream for me on this one and I straight away advised her to head to Lake Taupo. Of course to any one without local knowledge or a familiarity with historic eruptions, this would not be of any significance. To be honest neither would me telling them I want to go swim in a random lake in New Zealand. So I decide to write a peace on one of the largest eruptions in the past 70,000 years to explain just why it is so important.

With a surface area of 616 square kilometres (238 sq mi), it is the largest lake by surface area in New Zealand and the second largest freshwater lake in Oceania. Now it’s a popular tourist destination, an area of true natural beauty, but this tranquil lake was born from a violent even which occurred roughly 26,000 years ago.

Volcanoes graphicThe Taupo volcanic zones spans a hug area in North Island 350 kilometres (217 mi) long by 50 kilometres (31 mi) wide. Mount Ruapehu stands 2797 high and marks its southern limits, while a submarine volcano, Whakatane volcano, 85 kilometres (53 mi) beyond White Island is considered it’s north-eastern.  Several volcanoes in the zone are still very active with Ruapehu and Tarawera causing New Zealand’s most deadly eruptions in the past few centuries (both events killing around 150 people each). None of these small events come close to the Taupo volcano itself after which the zone is named. The zone is caused by east-west rifting within plate the at a rate of 8mm per year, slowly pulling the Northern Island apart.

 

Taupo’s last eruption is referred to as the Hatepe eruption and has be dated at roughly 180 AD was a VEI 7 making it one of the largest in the past 5,000 years. It coincided with reports as far away as Rome and Northern China of brilliant red skyies and disruption to climate for several years. Haptepe spewed more material in to atmosphere than several of the largest eruptions of this century combined, but still it was nothing compared to the event which form the Taupo caldera and in turn Lake Taupo; the Oruanui eruption.

The Unit as the level of the volcanologists feet is an exposure of an unwelded pyroclastic flow deposit from the Oruanui eruption. The light- coloured air fall pumice are from varying eruptions between Oruanui and the uppermost layer of deposits which were laid by the Hatepe eruption.

Its hard to imagine what the Northen Island looked like before the Oruanui eruption 26,500 years ago with out the gapping hole that is Lake Taupo at its heart. The eruption released an estimated total of 1,170 km3 (280 cu mi) of material, a VEI 8 eruption making it the largest eruption of the past 70,000 years. It effected climate world wide for decades, many people saying it had a helping hand in the last glacial maximum. The effects are hard to comprehend when the largest volcanic eruption in human times was only a fraction of the size.

The eruption caused the Taupo magma chamber to collapse on its self creating the vast caldera which today Lake Taupo occupies just over two thirds of. Ash fall deposits from the eruption have been documented over 1000 km on Chatham Island showing the intensity of the blast. An event like this would decimate modern day New Zealand quiet possibly leaving no survivors on the Northern Island if not enough warning was given. Luckily though all is peaceful and scerene on the shores of the Great Lake and no threat appears to be imminent. That said Taupo still shows us gentle signs of the power beneath with its Craters of the Moon tourist attraction filled with steam vents and mud pools as well as numerous hot springs.

When people ask me why I study volcanology when the risk is “minimal” to human life in comparison to say earthquakes or flooding, this is a prime example which shows how little people know about what our planet is capable of. So Ginge, I hope you enjoy your trip and now understand a little more why Taupo is one part of your adventure I sincerely wish I was there!

 

Figure 1; http://www.waikatoregion.govt.nz/Services/Regional-services/Regional-hazards-and-emergency-management/Lake-Taupo-Erosion-and-Flood-Strategy/

Figure 2; http://www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes/New-Zealand-Volcanoes

Figure 3; http://volcano.si.edu/volcano.cfm?vn=241070

 

As Yellowstone Melts…..

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Yellowstone has long been a favourite among conspiracy theorists and scare mongeres alike. The national park is atop a magma chamber now estimated to be at least 18 miles wide and between 3 and 9 miles deep*. This creates some of the most famous and stunning hydrothermal activity in the world such as Old Faithful geyser that erupts on average 18-21 times a day**. It makes it almost impossible to deny that this supervolcano is still very active despite being around 640,00 years since its last eruption. Each past super eruption has spewed out in excess of 1000 cubic kilometres of material. The largest eruption in recorded history was Tambora’s 1815 catastrophe which only erupted about 50 cubic kilometres, yet was enough to change world climate for several years and kill over 100 000 people.

Lately Yellowstone has hit the headlines for a less extreme reason. Roughly 3 miles Firehole Lake Drive, a road leading to Old Faithful, had to be closed as the aspsalt had melted. Of course this lead to headlines of impending doom and an eruption around the corner as magma must be rising and melting the roads. Truth is this is normal behavior in a system as large as Yellowstone, there road closures are almost routine. Asphalt will start to soften at the low temperature of just 50 degrees Celsius and will be liquid at about 250. The rhyolitic lavas which typically erupt from the volcano have lows of  500 degrees Celsius which, if rising magma was a cause, would mean the road would be a near constant river state. The melting is actually cause by the same system that feeds Old Faithful, water. Water has an exceptionally high heat capacity which means ground water any where near the volcanic system can run at extremely high temperatures and either explode out to the surface as steam like at the geysers or heat the surface causing roads to melt.

This is a very common occurrence at Yellowstone and other volcanic sites around the world and is not a sign that Wyoming is about to blow. The Yellowstone Observatory*** constantly monitors activity in and around the park currently have alert levels set to normal. Seismicity is said to be at “normal back ground levels” and caldera uplift continuing as it has been at a slow rate since the beginning of the year now at about 3cm. If there were any signs of impending doom we should be able to know in advance.

 

* http://phys.org/news/2013-12-yellowstone-magma-bigger-thought.html accessed 17.7.14

** http://www.wyomingtourism.org/articles/detail/Old-Faithful-in-Yellowstone-National-Park/405167 accessed 17.7.14

*** http://volcanoes.usgs.gov/observatories/yvo/ accessed 17.7.14