Yellow Stone National Park- The next supervolcano?

In 1971, a young geologist named Mike Voorhies came across a perfectly preserved.skull of a young rhinocerous in eastern Nebraska.  It turned out that he had just dicovered the most extraordinary fossil beds of North  America, which is known today as the Ashfall Fossil Beds State Park.  It was a dried up water hole around  which was a mass grave for many animals. All had died due to a sudden event which occured two million years ago in the Miocene period.  The animals were found to be buried under volcanic ash 3 meters deep. It was intriguing that there were no volcanos nor have there been any volcanoes in Nebraska.  At  first they thought that the animals were buried alive, but soon realized that the animals hadnt died  suddenly.  They were all found to be suffering from hypertrophic pulmonary osteodystrophy, which you contract when you breathe a lot of abrasive ash..  Such ash is found for hundreds of  miles around this area. The ash at that time would have buried the grass and turned the water in the watering hole into an undrinkable sludge.   The million dollar question was where did all this ash come from?  Voorhies sent ash samples to colleagues in the western United States asking if anybody could help.  Bill Bonnichsen from Idaho Geological Survey informed him that the ash samples matched a volcanic deposit from a place called Bruneau-Jarbidge in southwest Idaho, which is located 1600 kms. away.  It is a known fact that there is a huge cauldron of magma under the western United States, which erupted cataclysmically every 6,00,000 years. The last eruption in this region also occured six hundred thousand  years ago!  The hotspot is still there in what is known today as the Yellowstone National  Park.

In 1960, Bob Christiansen of the United States Geological Survey tried looking for the Yellowstone volcano, but strangely enough, couldnt find it.  He was particularly looking for a caldera (Latin for cauldron), which is a vast subsided pit which occurs after a single mighty rupture.  Christiansen happened to accidentally glance at some high altitude  pictures taken by NASA of the Yellowstone park.  It suddenly dawned on him that the whole park 9000 square kilometers of it was the caldera.  The explosion had left a crater 65 kilometers wide. That is why he couldnt spot it from the ground.   At some point in the past Yellowstone must have blown up with a violence, the magnitude of which cannot  just be imagined.  Prof Bill McGuire of University College, London says that when it erupted one wouldn't be able to get within one thousand kilometers of it!

Yellowstone  sits  on  top of an enormous hotspot.  Beneath the surface lies a magma chamber which  is about 72 kms.  across.  The pressure from  the magma chamber on its crust is what  has lifted the park and sorrounding areas half a kilometer higher. The heat from the hotspot is what powers all the park's geysers, vents and hotsprings.  Since its first  eruption 16.5 million years ago, it has blown up about a hundred  times.  The last eruption was atleast a  thousand tiimes bigger than St. Helens, and the one before that was atleast 2500 times bigger.  The yellowstone eruption which occured 2 million years ago, threw up enough ash to bury New York state to  a depth of 20 meters and California to a debth of 6 meters. The ashfall from the last eruption coverd all or parts of 19 western states.

                                         Volcano Eruption Mount St. Helens May 18, 1980 USGS
                                 
The last supervolcano erupted in Toba, Northern  Sumatra 74000 years ago. Greenland ice cores reveal that the Toba eruption was followed by 6 years of volcanic winter.  The event might have carried humans to the brink of extinction,  reducing the global population to a few thousand individuals.  For the next 20.000 years the population remained at the few  thousand level.  That is a long time to recover from a single  blast. A supervolcanic eruption like Yellowstone could wipe out mankind from the face of  this earth.

                                       TIME BOMB: YELLOWSTONE'S SUPER-CALDERA READY TO BLOW?

If the Samalas volcano which occured in 13th century was the mother of volcanoes, the yellow stone volcano will easily qualify to be the great  great grand  mother of volcanoes.  All the experts agree  on one thing, the yellowstone volcano is certain to erupt, and if and when it does heaven help us.  The worst  part  is that it is due anytime now.

Source:
Bill Bryson: A short history of  nearly everything

Supervolcanoes- Samalas Volcano, The Mother Of All Volcanoes

I first came across the term "Supervalcanoes" in Bill Bryson's 'A short history of nearly everything'. It was a really fascinating book, which lists out the possible scenarios which could bring about the end of Homo sapiens, one of which happens to be a "Super volcano". Yesterday, I came across an article in the 'Hindu' about a 13th century eruption in Indonesia, which by all accounts could be called the mother of all volcanoes in the last 3700 years. I followed up on that story and came across some very interesting and scary facts.

Scientists had always suspected that a massive catastrophic event had triggered of what is known as the Little Ice Age, sometime after 1250. The Little Ice Age has been abundantly depicted in contemporary accounts of advancing mountain glaciers that destroyed villages and paintings of ice-skating on frozen Dutch canals or on London’s River Thames. Chilling of the Northern Hemisphere was pronounced: cold summers, incessant rains, floods, and resulting poor harvests, according to medieval records. A volcano in Indonesia may be the location of a massive “mystery eruption” that has perplexed volcanologists for decades, according to a new study. The Indonesia’s Samalas volcano, is part of the Rinjani Volcanic Complex on Lombok Island.



Segara Anak Crater Lake formed after the eruption


The eruption occurred in 1257, and it could have been one of the events that started a 600-year cold period called the Little Ice Age. The previously unattributed eruption was an estimated eight times as large as the famed Krakatau explosion (1883) and twice as large as Tambora in 1815,

Volcanic eruptions release sulfur into the atmosphere. After cooling the Earth by reflecting sunlight, this material eventually falls back on Earth and gets deposited on ice sheets. These sulfur samples can be identified in ice cores obtained from polar regions. From the records, Clive Oppenheimer, a volcanologist at the University of Cambridge, found that an eruption in 1257 could have been responsible for the largest release of sulfur in the past 7,000 years.

But locating the volcanic source can be tricky. For the 1257 eruption, there were many candidates: Okataina in New Zealand, El Chichón in Mexico, Quilotoa in Ecuador, and Samalas in Indonesia.

To narrow down their choice, Franck Lavigne at the Pantheon-Sorbonne University and his colleagues had to consider many types of data, as they describe in a paper just published in the PNAS. They combined historical data, geochemistry evidence, carbon dating, and physical data to arrive at the conclusion.

The cataclysm blasted 10 cubic miles (40 cubic kilometers) of debris up to 27 miles (43 kilometers) high into the sky, producing fallout that settled around the world. Near the volcano itself, it settled into thick deposits that the team sampled in over 130 places to produce a stratigraphic and sedimentologic picture of the way the eruption unfolded. Further afield, the volcanic sulfate and tephra became locked in ice core samples taken from both Greenland and Antarctica.

Volcanic eruptions can have a large impact on the climate, which will then have social, economic, and environmental knock-on effects. Though the eruption was equatorial, its impact was felt and noted around the world. "The climate was disturbed for at least two years after the eruption, Medieval chronicles, for example, describe the summer of 1258 as unseasonably cold, with poor harvests and incessant rains that triggered destructive floods—a "year without a summer." The winter immediately following the eruption was warmer in western Europe, however, as would be expected from high-sulfur eruptions in the tropics. The team cites historical records from Arras (northern France) that speak of a winter so mild "that frost barely lasted for more than two days," and even in January 1258 "violets could be observed, and strawberries and apple trees were in blossom. In Indonesia records describe a catastrophe of a far more destructive and immediate sort. Found written on palm leaves, the Old Javanese texts of theBabad Lombok describe a massive volcanic blast that formed a caldera at Mount Samalas, on Lombok Island. The writing describes the deaths of thousands of people due to deadly ashfall and pyroclastic flows that destroyed Pamatan, capital of the kingdom, and surrounding lands. Archaeologists recently put a date of 1258 on the skeletons of thousands of people who were buried in mass graves in London. "We cannot say for sure these two events are linked but the populations would definitely have been stressed," Prof Lavigne told BBC News.

Source:

BBC news

National Geographic News

IBT Times