Supervolcanoes are volcanic explosion so great to have dramatic consequences on the life of the planet. Most of these huge eruptions have occurred in the distant past and therefore were only discovered them by the examination of geological strata. A supervolcano first unknown has just been detected in Italy, in Valsesia, Piedmont.
The volcano had a diameter of 13 kilometers and erupted during the Permian, about 250 million years ago. A troubled period for the planet, since in the same period lava and magma escaped from the crust and flooded a huge area of Siberian plain, there is also a possible impact of an asteroid in Australia and certainly there was the most severe mass extinction in the history of the planet, which killed 96% of marine species and 70% of plants, insects and reptiles. The intense volcanic activity and perhaps also the fall of asteroids caused a cloud of ash that blocked the sun across the planet, acid rain, and for some years, cold winters. But soon the carbon dioxide and methane released by volcanic eruptions caused a major greenhouse effect, with a rise in global temperature from 6 to 10 degrees, which may seem few, but instead had a catastrophic effect because caused a chain reaction with acidification and lack of oxygen in the ocean and the destruction of much of its life. A similar effect is what many scientists might occur with global warming caused by man, if the temperatures will rise by 4 or 6 degrees over the next century.
About 50 million years later there was another dramatic extinction of half of all living species on the planet. Again it is believed that the trigger has been an intense volcanic activity in the area of the Atlantic Ocean, with lack of oxygen in the sea and greenhouse effect. The volcanic activity, probably accompanied by devastating earthquakes, around 200 million years ago can be explained also with the beginning of the separation of Pangea, the continent that at that time encompassed all land on the planet.
A smaller-scale mass extinction occurred 116 million years ago and involved mainly the life of the oceans: in this case, the main culprit is underwater volcanic activity in the Java Sea area and current India, then not united to Asia but in the midst of the sea.
The next mass extinction occurred 65 million years ago, with the death of 75% of living species on the planet, including dinosaurs. In this case, the catastrophe does not seem attributable to the movement of continents, which had largely already reached the current position, but with the impact of at least two giant asteroids, one in the Mexico and one in India. The devastating impact of the asteroids would most likely result in earthquakes and volcanic eruptions around the globe.
But the next huge eruption of a supervolcano of which scientists found traces occurred in Colorado, United States, 28 million years ago. Although the eruption must have caused a huge cloud of ash throughout North America and to the Caribbean, it seems that did not result in mass extinctions, at least not in the scale of the above, but may have contributed to the cooling of the planet at the end of Oligocene, with the transition from a warmer climate to one more similar to ours.
According to some scientists, the eruption of Lake Toba supervolcano about 75,000 years ago caused mass extinctions and a (relatively) brief ice age, reducing the human population at the time and also estinguishing all the human species living, as men erectus and habilis, except Neanderthals and Sapiens.
The last great mass extinction in the history of the planet is the one that occurred about 12,000 years ago, which led to the extinction of many large mammals like mammoths, giant sloths, saber-toothed tigers, but for this event one of proposed explanations is the fall of an asteroid or meteorite, or climate change due at the end of the Ice Age, because it doesn't seems that there were major volcanic eruptions during that time.
Other supervulcanoes erupted in several areas of current United States and in several other areas of the world in other periods, and in more recent times, causing volcanic winters around the world, ie one or two years of cold temperatures and heavy snowfall, such as the eruption of Mount Tambora in Indonesia in 1815, which caused tens of thousands of deaths and the famous "year without summer", or the eruption of Krakatoa in 1883, which caused lower global temperatures and also beautiful sunsets, due to dust in the air.
For scientists, the supervolcano of Valsesia is particularly important as it will allow to study the ascent of magma from 25 km deep, to figure out how these huge explosions work and also when and where will be the next one. Some supervulcanoes that are kept under constant monitoring are the Yellowstone caldera in the United States and Campi Flegrei in Italy. Supervulcanoes eruptions of the most catastrophic kind occur only about every 1 million years, which is a very long time considering the written human history that covers just 5000 years, but it is very likely that sooner or later the planet will experience another such devastating explosions.
Francesco Defferrari
Francesco Defferrari
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