This will be my first report ive actually ever done in my life, and the first that Ive posted on ATS regarding Supervolcanos, hope you all enjoy it.
Here is some interesting facts about both volcanoes and the eruptions ive based my research on.
TAUPO (The Oruanui Eruption) - New Zealand.
- Happened 26,500 years ago.
- Known to be the Earth's largest eruption in the past 70,000 years.
- Is in one of the most active geothermic areas in the world.
- Erupts every 900years (Its been 1,700years since its last eruption)
YELLOWSTONE (Lava Creek Eruption) - USA.
- Last eruption happened 640,000 years ago.
- One of the worlds largest active volcanic systems.
- Ejecta volume exceeded 1000km2.
- Yellowstone's caldera is about 50 miles across.
So anyway back to: Yellowstone Vs. Lake Taupo.
Both of these Supervolcanoes have had dramatic eruptions in the past.
The reason for choosing these two Volcanoes is simple, i will use these similarities for comparing these two massive Supervolcanoes .
1. Both have ejected huge volumes of rhyolite magma.
2. Each eruption formed a caldera.
3. Both leaving extensive layers of thick pyroclastic-flow deposits.
4. Both the Calderas are approximately the same size.
5. Both are in the VEI (volcanic explosivity index) of category 8.
Roughly a VEI-8 Supervolcano can have a chamber with a spherical volume of 10 trillion cubic meters (a sphere with a diameter of 26kms (17mi aprox.)
Look at the San Francisco Bay Area, as though from a very high altitude, the diameter of the sphere would be around the same distance between the San
Mateo bridge to the Oakland bay bridge, 16 miles.
A few other VEI-8 Supervolcanoes are;
Long Valley Caldera, California, United States.
Lake Toba, Sumatra, Indonesia.
1. Both have ejected huge volumes of rhyolitic magma.
Rhyolite is viscous magma with high Silica content. If the magma doesn't contain gas, rhyolitic tends to just form a Lava dome.
However, when mixed with gas or steam rhyolitic eruptions can be extremely violent. The magma froths to pumice and ash, which is then thrown out into
the atmosphere with great force.
If the material thrown out cools quickly, it becomes heavier then the air and collapses (like water from a waterfall), causing a pyroclastic flow.
After a pyroclastic flow, the sufficiently hot pumice and ash settle, and stick together; forming what is known as 'Ignimbrite'.
After the Oruanui Eruption at Taupo much of the North Island of New Zealand was covered in Ignimbrite 200m (660ft) deep, and 18cm on the Chatham
Islands 1,000km (620mi) away. While the pyroclastic flow that devastated the surrounding area climbed over 1500m (5000ft) to over-top the Kaimanua
Ranges and Mt. Tongariro, only stopping after reading Mt. Ruapehu. This covered the land with Ignimbrite deposit, flattening all vegetation and
sending Lahars of pumice down all the main rivers including the Waitako river (Which originally ran though the Hauraki Plains). The ash/pumice sheet
generated spread from Napier to Auckland, and the ash was even reported making the sunset red over Rome and China.
- 430km3 (100 cu mi) of pyroclastic fall deposit.
- 320km3 (77 cu mi) of pyroclastic density current (PDC) deposits of mostly Ignimbrite..
- 420km3 (100 cu mi) of primary intracaldera materials
- 530km3 (130 cu mi) of magma (99% rhyolitic 1% mafic)
A diagram of Taupo's latest ans substantially smaller Hatepe eruption along side some of histories other major eruptions.
During the Lava Creek Eruption in Yellowstone 1,000km2 (240 cu mi) of ash was deposited from a pyroclastic flow with created the Lava Creek Tuff we
2. Each eruption formed a caldera.
A volcano is supported by magma. Magma holds up the land surface, or volcanic edifice. When an eruption expels a large volume of magma this support is
removed, causing the volcanoes dome to collapse. This collapse is what forms a caldera or "crater lake".
Yellowstone and Taupo being roughly the same size have had very different histories.
Taupo erupts on average every 900 years (it has been 1,700yrs since its last eruption) and according to geological records has erupted 28 times in the
last 27,000 years.
While Yellowstone has had 27 known eruptions over the last 2.1 million years.
Taupo's caldera was formed in the the event 26,500 years ago known as the Oruanui eruption. It caused several hundred square kilometers of
surrounding land to collapse and form the caldera. It is possible that the Lake Taupo event contributed to starting the Last Glacial Maximum.
Yellowstone's first caldera forming eruption occurred 2.1 million years ago. The eruptive blast removed much magma from its subsurface reservoir that
the ground above it collapsed into the magma chamber and left a depression in the ground- the huge crater measured 80 kilometers long, 40 kilometers
The reason i have compared the two in how their calderas formed is because the magma chambers were of different sizes. But, both volcanoes have had
the same devastating effects on the surrounding landscape.
Yellowstone's caldera being between 30x40km2 and magma chamber can hold an estimated 25000km2 of magma, and 4mi deep below the Earth's crust.
Taupo's caldera measures 185m (610 ft) at the deepest point, with the magma chamber being around the same estimate. With the Magmatic chamber being
an estimated 5mi below the Earth's crust around the Taupo volcanic zone.
Geothermal areas around the volcanoes
Both areas of interest (Taupo and Yellowstone) have very high geothermic activity.
Yellowstone holds the record for having the highest concentration of geysers in the world, and is one of the most active volcanic areas on Earth.
While the Taupo volcanic zone is one of the most active geothermal areas in the world with 12 active volcanoes and 30+ geothermal hot-spots including
what was the Pink and White terraces (destroyed by the eruption of Mt. Tawawera) from Mt. Ruapehu to White Island. This is caused by the subduction of
the Pacific tectonic plate moving in an easterly direction beneath the Indo-Australian plate, which allows magma to rise in large quantities. The
Waimangu Geyser was the largest in the known world. Eruptions from Waimangu would typically reach 160m (520ft) and some super-bursts reached an
astonishing 500m (1,600ft).
(will have to come to a conclusion now running out of characters haha)
In our lifetimes (say 70 years), I believe that Yellowstone seems more likely to explode, and thats only if the geysers stop erupting. As long as they
are working the volcano will have a means to release all the pent up energy under the Earth's crust. Many believe that the geysers working is a sign
that Yellowstone will soon erupt; which isn't the case at all. But, if Yellowstone did erupt it will cause a lot more devastation in a wide spread
area of about 3 states and cause a lot of death. If it is the next Super-eruption it could possibly effect the Earth on a worldwide scale.
If Taupo did erupt, i dont think it would be a worldwide catastrophe, more of a nationwide one. New Zealand would be in turmoil from the eruption for
a long time, effecting the rest of the world seeing as how you get our good fruit and vegetables and the good meat and milk, haha.
Will add more to this tomorrow