Wide mouth for concern

Supervolcanoes long not notice, because they are very large and very long time not erupted

  

Show all, of what, Vesuvius has long become one of the main attractions of the Bay of Naples. Photo: © Argenberg

Science noticed this lurking danger under the feet of humanity has only recently — and yet one could not become a volcanologist witnessed its revival. But they ask their gods to prevent this from happening.

Bomb under Naples

Two thousand years ago, the eruption of Mount Vesuvius buried the multimeter under a layer of ash and rock city of Pompeii, and covered with a cloud of hot pyroclastic flow Herculaneum. In the story it was included as one of the worst natural disasters, as a symbol of breaking the power of Mother Nature. Breathtaking and terrifying mind of the ancient Roman cities of death has been displayed in literature and cinema, and the famous painting by Karl Briullov all probably still remember from school.

However, a number of sensational discoveries made in recent years have shown that no more formidable than Vesuvius boil on the body of an old woman-the Earth, compared with the more grandiose volcanic formation, sleeping in the depths of the earth's crust nearby.

To the west of the ancient and beautiful Italian city of Naples is a place called Phlegraean Fields (Campi Flegrei). If you fly over it on a plane, you can see that all of it is covered by the ancient, half-smooth erosion of volcanic craters. Roads, racetracks and houses built right at their feet, and even within — as the former fire-breathing vents eventually turned into a giant bowl with a relatively flat bottom.

Another forty thousand years ago Phlegraean Fields were a living hell — the volcanic activity in the area was much higher than that of Vesuvius.

But sailed here in the VI century BC Greek colonists caught only a few wisps of smoke, making their way out from under the rocks. Actually, they gave the name of the place: "burning field" (from the Greek phlegreios).

Today, life in the dormant volcanoes is carefree. The only thing that reminds residents of the geological past of the Earth — is solfataras. Jets of steam and hot sulphurous gases escape from the cracks of a small crater Solfatara, which gave them the name. But this calm may be deceptive. Once just carelessly walked through the streets of Pompeii Romans.

  

Space probe "Galileo", flying close to Jupiter's moon Io July 3, 1999, was able to take a picture of what was happening there then supervolcano eruption, during which several calderas formed with a diameter of tens of kilometers each. Photo: University of Arizona

Study the Earth's interior using seismic tomography (Seismic tomography) showed that the area of Naples is resting on a huge magma pool of 400 square meters. km. According to volcanologists, this is a real time bomb that could explode once. But fear not only should the next eruption of Vesuvius.

Phlegraean Fields are not innocuous sites geological history of the planet. A more detailed study of them showed that the crater is covered by several tens of terrain represents the remains of a giant caldera of an ancient volcano, part of which is flooded waters of the bay of Pozzuoli.

Of course, in the world there are examples of other equally impressive large calderas. For example, the island of Tyre, "bagel" is — all that was left after the explosion in the XV century BC Santorini volcano. But research by the volcanic area of Naples continue, and who knows what they will open.

What if the Phlegraean Fields and Vesuvius — not two separate volcano (ancient and modern), and two "exhaust pipe" an older and far more grand volcano caldera which is the Bay of Naples? Of course, such an assumption can be called only while science fiction, but who knows!

But back in the least interesting scientific reality — to the Phlegraean Elysees. Thus, their study showed that they are the huge ancient volcano, now dormant — but has a slightly different design than, for example, a neighbor of Vesuvius. This type of volcano was the working title of supervolcanoes (supervolcano) — primarily for its size.

Fire Earth ulcers

A typical volcano, as we currently imagine it is a cone-shaped hill with a crater from which spewed lava, ash and gases. Formed so: in the depths of a volcanic center is the magma, the contents of which finds its way (path) through the cracks, fractures, and other "defects" of the Earth's crust.

As magma lifting off gas, turning in volcanic lava, and poured through the top of the channel is usually called a muzzle.

Otkalyvayas around vents, eruptive products and build up a cone volcano.

Supervolcanoes also have the feature, because of which, until recently, no one even suspected their existence. The fact that they do not look like familiar to us cone "cap" with a muzzle inside. I doubt whether they could build something like that — and not only because such a mountain would reach several tens of kilometers in the base and a height of 15-20, it just would fall into the ground, because that did not bark able to sustain such a weight. Actually, something like this happened.

Their centers are located much closer to the ground and is a huge magma reservoirs — and correspondingly large area of the horizontal section. According to one version, supervolcano eruption began with the fact that the magma melts and breaks up the layer of the earth's crust over them, sticking on the surface a huge hump (a height of several hundred meters and a diameter of 15-20 km or more).

Then the pressure increases, the magma is looking for a way out. On the perimeter supervolcano there are numerous vents and cracks — and then the entire central portion of falls down into the fiery hell. Collapsed rock, just a piston rapidly release large amounts of subsurface magma and gases — and they are released into the sky with giant fonts lava and clouds of ash cyclopean.

Such a phenomenon never seen before, not only volcanologists, but generally homines sapientes — all earthly supervolcanoes erupted long before they occur. But the question remains: is it was a rare geological phenomenon, or sometime in the era of tumultuous geological youth of the world with respect to their eruptions often shook her body? Status of their occurrence with periods of so-called "Increased volcanic activity" of the planet? Answers to these questions are yet to be found.

When a supervolcano eruption was over, he remained on the huge caldera, which was formed in a huge valley — a kind of "cap" over the magma chamber. Part of a "cover" her out of the corner, just be Phlegraean Fields. Thus, if a classic volcano can be compared to "pimples" that supervolcano is more like a serious hematoma or abscess.

  

In the caldera supervolcano in Sumatra creating Lake Toba. In the center of the lake the island of Samosir — a layer of volcanic ash on it reached six meters. Even in India, the ash from the volcano Toba went to bed in some places six meters. Photo: NASA / GSFC / MITI / ERSDAC / JAROS, and the US / Japan ASTER Science Team
His fate can be different. He can sleep peacefully, becoming a reservoir for the lake, the valley can get hot thermal springs and can sometimes play tricks with small eruptions, covered with volcanic cones. But it may erupt again — shaking the earth's crust. It all depends on the processes occurring in the subsoil.

To date, under the term "supervolcano" includes several objects. First, it is all the same Phlegraean Fields. Second, a volcano Toba in Sumatra, which last erupted about 74,000 years ago. Now his giant caldera area of 1775 square meters. km is filled with water and forms a very picturesque lake.

Ancient and very large supervolcano has been recently opened in Kamchatka. During the study area Bannykh sources, the Institute of Volcanology and Seismology found there remains of an ancient caldera. On closer investigation were set its size (25 to 15 km) and approximate age — about one and a half million years. Thus, it is several times older than most of the Kamchatka volcanoes. By the same version that is an ancient caldera supervolcanoes, has led scientists to study the dome uplift in its center — due to the presence of a powerful beneath the magma chamber.

But the most famous supervolcano — is Yellowstone National Park (Yellowstone National Park), is located in the Rocky Mountains in the northwestern part of the state of Wyoming (USA). Most thoroughly investigated, he also became the protagonist of the documentary film «Supervolcano» (BBC production) and the eponymous art thriller — representing it as the beginning of a possible eruption of the grand cataclysm.

Volcanic winter

Normal eruption of a volcano on a planetary scale — no more than an eerie sight. Shown in Hollywood movies, "Dante's Peak" and "Volcano" — nothing compared to what happens when supervolcano eruption. In hours will roll dozens, even hundreds of cubic kilometers of ash and lava. And to win the element with bulldozers and dynamite will not work — humanity can only watch and wait. Such is the sad moral of the audience «Supervolcano».

Detailed studies of the Yellowstone Park, famous above all for its geysers, began in the mid-twentieth century. Even then, scientists have come to the conclusion that his giant caldera (70 to 30 km) are clearly of volcanic origin. Of course, the mind refused to believe in the existence of volcanoes such size — needed so many years of research and theoretical developments, before a model was developed supervolcano.

In the course they became known that the last three Yellowstone supervolcano eruption occurred two million years ago, one million three hundred thousand years ago, and six hundred and thirty thousand years ago. Thus, the conclusion is that the eruption is more or less periodic, and the period — about six hundred and fifty thousand years. This means if the next eruption to wait a bit — of course, the geological clock. However, not all heard this specification and the United States swept the sensation, caught up in other countries and then embodied on the screen: the Yellowstone supervolcano will soon explode, save yourself if you can!

 

Forecasting the effects of global cataclysm is not only interesting, but also very sought-after job. These projections are very popular with millions of inhabitants, read and stare scenario coming "end of the world." So as soon as there were predictions about the date of the eruption of supervolcanoes, not long in coming and predictions of their effects.

So, in the first minutes after the collapse of the sky to a height of up to fifty miles, cock poles hot gases and ash. Pyroclastic flows simultaneously rush along the ground, burning everything in a radius of several tens of kilometers. And if the area is populated Yellowstone relatively small, such a blast Phlegraean Fields incinerate area that inhabited by millions of people.

After a few hours most of the ejected ash starts to settle, covering their entire state. Cities that are hundreds of miles from Yellowstone, the fate of Pompeii, of course, will not suffer, but the traffic will be very difficult — if not impossible. Moreover, volcanic ash — not snow, it melts in the spring, and during the fall, he clogs the respiratory human and animal disables machinery. Difficult to breathe and because of volcanic gases — which include sulfur compounds.

  

Seen Old Faithful geyser (Old Faithful Geyser) is a must item in the program of any tour of Yellowstone National Park. And now it can be viewed in real time via web-cam. Photo: Ed Austin / Herb Jones NPS

But the greater danger would carry the ash remains in the atmosphere: closing themselves sunlight, it can create the effect of "volcanic winter", almost no different from the "nuclear winter" — action due to the global nuclear conflict, and calculated for the first time twenty years ago, the Soviet mathematician Nikita N. Moiseyev. It is now believed that the eruption Tambora (1815), which was thrown into the atmosphere a few cubic kilometers of volcanic material, caused cooling global scale — in Europe led to the "year without a summer." Because of the eruption in 1816, came the last in the history of the pan-European famine. Tens of thousands of Germans then moved to Russia and the United States. But this is only flowers. Recent studies have shown that the eruption of the Toba supervolcano has led to a decrease in the average temperature of eleven degrees, and the resulting glaciation had dire consequences.

As you might guess, this disaster is like nuclear war or asteroid. But mankind can avoid war — if guided by reason, not emotion. Uninvited space "stranger" can try to knock down or reject using existing technologies. But the methods to prevent the eruption not only "super", but ordinary volcanoes yet — that's why these forecasts call, to say the concerns.

On the other hand, no reason to panic either. Described disaster could happen — but not tomorrow or next year. But a new reason to expect a "doomsday" soon appeared. So in we hear the new "sensation" of the imminent supervolcano explosion, and the collision of the planet with an asteroid, a black hole, and maybe even with the "celestial axis'.

Source: vokrugsveta.ru.

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