In June 2019, the British newspaper Daily Express reported that geologists recorded as many as 87 small earthquakes in the Yellowstone Volcano area in the northwestern United States within a month! The strongest of these was rated by the US Geological Survey at 2.5 on the Richter scale. Experts believe that such activity indicates the readiness of the famous volcano to wake up.
1600 degrees Celsius
The term "supervolcano" in relation to the Yellowstone caldera (basin) was first heard in the popular science documentary series "Horizon", which was shown in 2000 by the BBC channel. This is not a completely scientific term, but it is very accurate: due to its size and destructive potential, Yellowstone deserves the title of a supervolcano. The volcanic circus basin in the northwestern United States measures 55 kilometers wide and 72 kilometers long. Such data was provided by the Geological Survey of the United States of America. A huge plume feeds the volcano: this term denotes a stream of solid mantle rock, directed vertically upward and having a temperature of up to 1600 degrees Celsius. When approaching the topsoil, it turns into molten magma,which breaks out to the surface in the form of numerous geysers and mud pots that have made Yellowstone National Park famous.
According to scientists, the motion of the N American continental plate along a stationary plume has been directed to the southwest for several million years. At the same time, the plume constantly burns through the earth's crust, which is why new calderas appear and new strong eruptions occur.
We go according to the schedule
Science knows about three Yellowstone super-eruptions. He first declared himself 2.1 million years ago. Its power was such that mountain ranges collapsed like houses of cards, and the release of volcanic ash reached a height of 50 kilometers. For reference, this is the upper boundary of the stratosphere. The volume of the erupted ash was 2500 cubic kilometers. More than a quarter of North America was buried under it.
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The second time the supervolcano woke up after 800 thousand years. During this time, it has significantly weakened: the volume of the ejected volcanic substance was equal to "only" 280 cubic kilometers.
And finally, for the last time, Yellowstone spoke 640,000 years ago. The third time, it erupted with a force half that of the first. It was this last eruption that formed the well-known caldera. This rounded lowland with a circumference of 150 kilometers was formed as a result of the collapse of the volcano.
The first of the most dangerous
Yellowstone supervolcano tops the list of potentially dangerous dormant volcanoes, whose volcanic explosiveness index can reach a maximum of 7-8 points. The term “explosiveness” was coined by volcanologists in 1982 to determine how “explosive” an eruption was. At the bottom of the scale, there are eruptions with an index from 0-1 points. They occur almost constantly, but outwardly they look like a slow flow of lava and are not considered dangerous. But eruptions with an index of 7-8 points are capable of filling the territory of an entire city or even a small country with volcanic debris and ash. Fortunately, this happens once every 50,000 years. The second most explosive supervolcano is also located in the United States. This is the Long Valley caldera, which provides a "fun life" to the people of California. It was formed 760 thousand years ago. Since then, there have been eruptions every year. Experts believe that it is not worth expecting a change in the situation in the current century.
The world won't be the same
The volcanic caldera Toba on the Indonesian island of Sumatra was formed only 74 thousand years ago. It now houses the largest volcanic lake on Earth. However, the peaceful landscape is just an appearance. Constantly emitted volcanic gases and high soil temperatures indicate that the giant volcano is capable of waking up again. And the powerful volcanic activity in this geographical point can have the most serious consequences for global climate change.
The Phlegrean Fields Caldera under the Gulf of Naples was formed only 40 thousand years ago during an eruption with a power of 6-7 points. Currently, its magma mainly comes out only from Vesuvius, so not all scientists are ready to recognize the Phlegrean Fields as a supervolcano. But don't underestimate the danger. First, the caldera and its surroundings are densely populated, and the eruption could kill millions of people. Secondly, the ash cloud will inevitably cover Europe, destroying cultural and economic centers. I apologize for the cliché, but after this eruption, the world will certainly not be the same.
But the Caldera Aira in Japan has already played its role in the reconstruction of the planet. The only active volcano on its vast territory is Sakurajima volcano. He can only cause trouble for the nearby Kagoshima Prefecture.
But how can Russia do without its supervolcano? In 2007, scientists from the Institute of Volcanology and Seismology of the Far Eastern Branch of the Russian Academy of Sciences filled this gap by discovering a supervolcano in the country. This is the Karymshina caldera. It arose on the territory of South Kamchatka about 1.5 million years ago. The probability of the awakening of this volcano is quite high: it can be provoked by seismic instability near the Kamchatka Peninsula.
Winter and summer after the cataclysm
What consequences will the super-eruption have if it does happen?
First of all, no one will survive during a catastrophe in an area of tens of thousands of square kilometers from the epicenter. But those who survive will also have a hard time. Volcanic matter, which will not be liquid lava, as in conventional eruptions, but gas and ash, will enter the stratosphere. The particles of obsidian in the ash form a screen in the path of sunlight. Without receiving it, the planet will begin to cool down. A volcanic winter will last for years, perhaps decades. And when the dust finally settles, the huge amount of carbon dioxide in the atmosphere will create a greenhouse effect. Thus, anomalous winter will be replaced by an anomalous summer. Both will be detrimental to civilization. In addition, the presence on the soil surface of a layer of volcanic ash only a centimeter thick will lead to the death of all surviving agricultural crops,and acid rain will pollute water bodies.
Are we facing a fourth eruption?
Until now, scientists have given a very optimistic forecast, estimating the likelihood of the fourth eruption of the Yellowstone volcano in the near future as 0.00014% per year. The calculations were based on two time intervals between the known periods of activity of the volcano. True, the experts immediately made a reservation that it is almost impossible to reliably predict the course of such irregular geological processes. And it looks like they've done it.
In the spring of 2019, a new expanding thermal anomaly was discovered in Yellowstone National Park between Lake West Turn and the previously discovered Lake Turn geothermal zone - it was indicated by dead trees. And in the summer, the American media reported an unexpected discovery associated with the volcano. It turned out that its potential power had been underestimated for a long time: according to updated data, the volume of the hot hot rock under Yellowstone Park is 2.5 times larger than it was assumed, and it lies at a depth of 5 to 14 kilometers. This suggests that enough magma and gases have already accumulated under the surface for an immediate eruption.
Chilling blow
Humanity has long watched the Yellowstone Caldera with concern. Back in 2014, in one of the History Channel TV programs, University of Utah researcher Robert Smith made a statement that the seismic activity of the supervolcano is constantly increasing, leading to the destabilization of the tectonic fault in Yellowstone. His opinion was heeded not only by the audience, but also by NASA specialists. They developed a "pre-emptive strike" program against the troublemaker.
In their opinion, it is possible to prevent a sudden eruption of Yellowstone by drilling several giant mines near the supervolcano and pouring water into them to a depth of 10 kilometers. But geologists are expressing serious doubts about the safety of the project. High seismic activity in the Yellowstone area may serve as an obstacle. Tremors of 3 on the Richter scale are not uncommon here. And any human intervention in such an unstable system can have unintended consequences.
In addition, drilling of such a grand scale, taking into account the capabilities of modern technology, will last 10-20 years. All these years, the Yellowstone caldera will be tested for strength every day. But any violation of the earth's crust in the immediate vicinity of a supervolcano can trigger a chain reaction, the final link of which will be what NASA specialists are trying to avoid - a super-eruption. What this will lead to - read above.
Magazine: Secrets of the 20th century №30. Author: Svetlana Yolkina