Supervolkans

Publishing houses "Hummingbird" and "ABC-Atticus" represent the book of Robin Andrews "Superwulcans. The unexpected truth about the most mysterious geological formations of the universe ”(translation by Valentin Frolov).

Volcanoes are inseparable from the history of the Earth and all life on it. A volcanologist and scientific journalist Robin Andrews reveals the scientific and historical significance of volcanoes and volcanic regions and shows how they affect the formation of the sea, land and air composition.

“Volcanoes allow us to get into secrets that no other natural process can discover. The peaks, craters and clefts are formed, acquire a certain shape and erupt because, and only because planetary motor vehicles located deep under the surface of the planet work in a special way. Evils give us gold discoveries. They suggest why there is water and atmosphere on one planet, but on the other not; where the continents break into parts, creating a new ocean; Whether the surface of the planet consists of pieces of puzzle, the movement of which sets the shape of everything that happens on the surface. They transfer us to billions of years to the past so that we can find out how the planets are born, and allow us to look into the future that can expect them. Volcanoes are an example of extreme stamina of life, which far exceeds human. They also show how whole worlds can and can not die, ”writes Robin George Andrews.

We offer to read a fragment of the book.

If the volcanoes as a whole have a bad reputation, then the Yellowstone volcano is truly terrible. In colloquial, it is called a supervolcan, which hints at the ability to commit serious acts of volcanic violence. Scientists know that he will not destroy humanity. But, largely due to excited shouts of boulevard newspapers and soothsayers from social networks, according to which Yellowstone is on the verge of catastrophic eruption, many people treat him as if this is a self -destruction button. In the midst of the Pandemia of Coronavirus, the Guardian newspaper reported that thousands of people gathered around the famous geysers of Yellowstone, not putting on masks and not observing the social distance. At the same time, I am ready to argue that quite a few of them asked the employees of the National Park service about the probability of supervolcanic apocalypse.

It is impossible to deny that Yellowstone in the past was distinguished by phenomenal destructive power. The history of its occurrence is a saga about geological destruction: it comes from a long series of volcanic ancestors, whose craters were created by the infernal emission of magma from almost the heart of the planet. This trace of scars can be observed throughout the western part of the United States: it extends hundreds of kilometers and returns us to the past for millions of years. But our volcano does not deserve to be perceived as a harbinger of death. Nothing forever, even supervolcans, and the happy days of the rage of Yellowstone, perhaps have long passed.

Everything that you, it seems to you, know about Yellowstone, is most likely wrong. This is not a killer awaiting in the wings. Superwalkans like him will not lead to the end of our civilization. For that matter, Yellowstone helps us understand that everything is transient in this exciting, constantly changing world - even the most powerful magmatic mountains and enormous boilers of the Earth.

Archaeological data indicate that people appeared on the Yellowstone plateau about 11 thousand years ago. The indigenous Americans from generation to generation lived side by side with smoking geysers, damaged soil and boiling waters of this region. But only in 1871, when the US Congress financed the expedition under the leadership of Geologist Ferdinand Hayden with the task of documenting the aesthetic virtues of Yellowstone (in articles, works of art, photographs), legislators and President of Ulysshs decided to make something unprecedented - to officially declare the first national park in the world.

The law signed on March 1, 1872 states that the Minister of Internal Affairs has exceptional control over the ground and must protect the “wood, mineral deposits, natural attractions within the specified park” with the aim of “preserving them in a natural state”. The Yelloustown National Park with an area of ​​8983 square kilometers existed even before the states in which it is located - mainly Wyming, with small plots in Aidaho in the west and Montan in the north, joined the Union of the United States. The first days of his existence were chaotic and chaotic. The territory often became an arena of battles, various tribes of indigenous Americans tried to defend themselves from the US warlike army (the service of national parks did not exist until 1916).

From a geological point of view, the park is a real treasury. Park employee Jefferson Hangerford told me that some breeds in the park belong to the Archean Eon when the land was only formed. And here new breeds are still created, since minerals crystallize in numerous thermal sources of the park (there are about 10 thousand in total).

A large prismatic source can be considered a symbol of Yellowstone. The size of a football field, it looks like an inter -spatial oasis. Its pupil is an unearthly deep blue color, and the adventurous bacteria living in its bizarre waters stain the iris in yellow, orange and green shades. In winter, snow, sticking on a rocky eyelid, turns into steam.

Other thermal springs are less friendly, but no less remarkable. Sulfuric hills located on the north side of Lake Yelloustone, when viewed through the thermal imager, look like a bright red spot. This area has long been considered the earth of fire and sulfur: hydrogen sulfide gas is erupted from the Earth, creating acid anti -utopia hostile to vegetation and animals. “If you put your finger at the ground, you will get a burn,” says Greg Vogan, a researcher at the US Geological Service. “You are unlikely to arrange a picnic there, all pants will be in holes.”

There are also about 500 geysers in Yellowstone - half of all geysers on the planet. One of them, the "steamer", throws out the fountains of water to a height of up to 120 meters. In the past, it was unstable, the pauses between major eruptions lasted from four days to 50 years. March 2018 was marked by changes: the geyser began to erupt with the frequency of once a week, and as a result, a record number of eruptions occurred in the year-32. In 2019, 48 eruptions were recorded, as in 2020.

It is unclear what could change in the upper piece of the earth's crust, rocky glaze on the puff cake of the earth to activate the geyser. Perhaps the minerals settling in a watery decoction under the surface blocked the path up, turning a shallow pool with liquids into a pressure cooker. Liquids that can boil faster, began to rise more often to the surface. Or, perhaps, abundant snow over the past few years has provided an underground layer with a large amount of water, which fed frequent emissions of the “steamer”. Since there are no devices that would allow you to track the parameters of this complex chemical cycle under the surface, accurate answers simply do not exist. But the temperamental behavior of the “steamer” is typical for almost all geysers, since their water supply is constantly being rebuilt. And changes are a distinctive feature of Yellowstone.

The Steamboat is located in the Geizers basin Norris. The age of the oldest thermal basin of Yellowstone is about 115 thousand years, its temperature reaches 240 ° C directly under the surface. As if the monster made holes in the devilish pot. The pool is an accumulation of hot springs, geysers and fumarol, hundreds of separate thermal objects that hiss, turn, collapse, erupt and boil. But in comparison with the main attraction of Norris, this is just small fun. Over the past two decades, the territory larger than Chicago, located around the pool, periodically rose and dropped a few centimeters, as if the beast sleeping underground had inhaled and exhaled. Other parts of the park are also swollen and blown away on a similar scale, but at some point the earth in Norris rose at a speed of almost 15 centimeters a year: this is the fastest rise, ever recorded in Yellowstone. This is probably because hot liquids get stuck in the bark, make her rise, and then, finding a new path out, again allow her to sink.

There are no rules and an established order in Yellowstone. Entire thermal zones die, while others are born with amazing speed. Ask the Vogan who has been watching Yellowstone for 12 years. Using a lot of mechanical eyes in orbit around the Earth, he watches as the park the mysteriously changes, refusing to freeze at least for a short time in immobility.

In 2017, he noticed a plot of dead trees in the depths of the park-wooden corpses that have grown into pale yellow warm soil. Archival satellite and aerial photographs allowed to track how their death occurred until the end of the 1990s: their fate was a foregone conclusion when a new thermal zone appeared, which had grown to the size of four football fields in a few decades. “This is a very large thermal zone that has been sneaking up to us for the past 20 years, and I found it only a couple of years ago,” says Vogan. - The rangers of the park did not notice anything. The zone could only be seen if you go on a kind of time travel, looking at the pictures from the cosmos. This is evidence of how great Yellowstone is. ”

Changes, as they say, come from the inside. Do not forget that Yellowstone is a volcano. All his tricks exist on the surface only because in the darkness of the depths, two giant tanks of magma, which are superior to the size of entire cities, do not calm down for a second.

And now we need a short course on tectones of the plates. The surface of the planet is a giant puzzle. Separate pieces are huge rocks of rocks the size of the country, continents, seas or oceans. They consist of two layers. Above is the earth's crust, which is of two types: the breeds of which the continents consist, and the breeds that form the seabed. Under the bark there is a mantle - an overheated, viscous, but mainly hard layer with a thickness of 2900 kilometers. The tiny upper piece, the hard upper part of the mantle, is the basis of tectonic plates.

These sandwiches from the bark and upper mantle are called lithospheric slabs, but you could hear the term “tectonic slabs”. They are located on top of an even softer, more plastic layer of a mantle called an asthenosphere. Hard tectonic plates are drifted on this more supple lower layer of the mantle, and all of them move in different directions.

Tectonic plates have names (but not like jasmine or David, alas). Most of the United States is located on the North American plate of the same name. Like all other plates, it rummages and bends around the edges under the influence of other neighboring slabs - from the Pacific plate in the west to the Eurasian stove far in the east in the Atlantic. This means that most earthquakes in America occur along these boundaries, but there are exceptions. In Western Weyming, for example, the earth's crust is very slowly moving apart. This leads to earthquakes, many of which are invisible to humans.

This is the great news for those who want to make a computed tomography wioming. Seismic waves that occur during earthquakes pass through different materials with different speeds and along different trajectories. They quickly slip through more dense substances, but through the liquids they move very slowly. Hot and slightly molten materials, less dense and less rigid, pass them slower. Scientists, by definition of people smart, realized that the path of seismic waves from an earthquake to a seismometer can be used to find out what the underground world consists of: of molten or solid breed. Over the past few decades, they intercepted seismic signals of a huge amount of earthquakes, and as a result received an idea of ​​the magmatic bowels of Yellowstone.

There are two interconnected magmatic tanks in Yellowstone. The smaller has a length of 90 kilometers and extends from 4.8 kilometers under the surface to a depth of 17 kilometers. This long mass of riolite, a very liquid type of magma, is more than four times higher than the length of Manhattan.

But this is only the youngest of the brothers. The veins of the molten rock flow down from the base of this upper tank of the magma, like the threads of soft caramel, and connect with an even larger monster: the extended mass of the basalt - a more liquid and hot type of magma, familiar to us through Kilauea, extending to a depth of 19 kilometers under a surface of up to 50 kilometers. It is four and a half times larger than the upper magmatic reservoir: this is enough to absorb the whole New York.

Together, these tanks are like a two -chamber engine that drives the dance of geysers upstairs. But here is not a direct connection: this is not magma forces to circulate liquids and gases under the surface. The heat from the upper magmatic reservoir passes through its rocky roof, from where it breaks to the upper layers of the soil. This residual heat heats the rocks a little away from the surface and brings to a boil of water deposit.

I keep a bet that in your mind, a vague image from school textbooks or some kind of cognitive television program with computer animation suddenly arose: a huge cave, filled with molten breed soup to the ceiling, a wide open pipe leading to a volcano on top. The term itself to indicate these phenomena - magmatic chambers - enhances the idea of ​​the floor of the lithological1 cathedral, which takes the reserves of the molten breed coming from the depths, and then emptys them from the high peak.

But that's the matter: there is no magmatic cameras. At least scientists have never seen them.

If you leave the block of ice in the sun, it quickly melts and turns into a puddle of water. Stones do not behave in the same way when they are exposed to sources of extreme heat. I know, because I myself threw volcanic stones into the furnace many times specially designed for their melting. They do not turn into puddles. Small pieces of volcanic breed are melted at lower temperatures, and larger ones are held until the thermometer rises to incredible values. This is because volcanic rocks are a set of minerals, each of which has its own melting point.

The same applies to the magmatic reservoirs of Yellowstone. The deeper you plunge into the earth's crust, the hotter it becomes. But at present, this temperature is not high that both tanks remain completely molten. If, say, pour a fresh portion of hot breed from below, then, of course, part of the tank will heat up and melt. But in general, we are talking about a solid breed with a network of molten magmatic reservoirs, pools and debris. Sometimes liquid breed is larger, sometimes less.

Yellowstone can be compared with a bizarre sponge, the holes of which are filled with hellish gelatin. This gelatin is hot than the frozen volcanic crystals surrounding it, and therefore has natural buoyancy - that is, according to the laws of physics, it should rise up. When lifting, he paves the way through weaknesses - for example, large holes in the sponge. In fact, magmatic cameras are not at all caves in the earth's crust, but tanks with hot mess, streams of partially molten breed, enclosed in crystals labyrinths. The real sponge of Welzebub.

The sponges of Yellowstone are huge, but now they are mostly a solid. Seismic data show that the upper reservoir has been melted by 5-15 %, and the bottom is only 2 %. Of course, their size is large, but now they are in a sleeping state, waiting for the return of extraordinary explosive activity, which was so many in the past by Yellowstone.

1. From the word "lithology" - part of the science of rocks, studying the composition, structure, origin and change in sedimentary rocks.