What are sinkholes and how do they form? The process of formation of sinkholes. The most impressive sinkholes
One of the most unusual landforms are sinkholes. These incredible formations occur due to the movement of soils in rocks, soluble in water. In nature, there are a huge number of karst sinkholes, about which will be discussed in this article.
Simply put, karst funnels are formed through the dissolution and leaching of rock layers by groundwater. As a result, the earth sags, and funnels of various sizes are formed: some do not exceed one meter, others go hundreds of meters into the bowels.
General information about karst processes
A rather serious obstacle is the occurrence of sinkholes in any area. This is especially difficult during construction work and the use technical facilities. In connection with the foregoing, the study of karst is an important and sometimes decisive element of engineering and geological research, especially in the construction of hydraulic structures.
There are some cases when, in the event of large karst formations lakes and entire rivers disappeared from the surface of the earth.
The word "karst" historically comes from the name of a plateau in Slovenia, in the Trieste region, which is calcareous.
Karst funnels in Russia are also quite widespread. They can be found on the Russian Plain, in the Urals, in the Angara region, on Far East and in the Caucasus.
Water-soluble rocks include limestone, chalk, dolomite, highly calcareous marl, salt, gypsum, etc.
In the process of construction work, it is imperative to take into account the occurrence of such a natural formation (karst funnel). The calculation of dimensions (diameter, depth, etc.) is very important when designing any work in such areas. In addition, in the process of site selection for construction and for the creation of safe design solutions for the construction of foundations, important point also represents the degree of activity of these processes. With active karst, the degree of karst increases, while passive karst developed sometime in the past. Therefore, in the latter there is no intensive and free movement of water, and it also contains the removal products of other rocks.
Kinds
Usually they talk about salt karst (chloride - voids in salt deposits), gypsum (sulfate - karst in gypsum) and carbonate (in limestone, chalk, dolomites or marble).
On the earth's surface, karst takes on a variety of shapes - cracks (in geology - karts), furrows, grooves. If such karsts are common in large areas, then they are called carr fields.
In nature, there are various forms of karst voids.
1. Karst sinkholes are the most common karst manifestations. In diameter, the dimensions of such funnels are from 1 to 50 meters (there are also 100 meters). Their depth varies from 1 to 20 meters. Distinguish between sinkholes and superficial sinkholes. Failures occur as a result of the collapse of rocks above underground voids. Surface ones are formed as a result of dissolution by atmospheric waters.
2. Panoramas - deep karst cracks leading surface (atmospheric) waters into underground pools.
3. The appearance of a karst funnel of a field occurs when several karst funnels are combined or when large areas of the earth's surface are lowered. By lenght this species karst reaches several kilometers, and the depth is several meters.
4. Caverns are formed as a result of dissolution of rocks in the place of numerous cracks.
5. Caves arise as a result of erosion, rock collapse, dissolution, mechanical suffusion. The sizes can be huge in diameter and reach several tens of kilometers in length.
Below are some of the most impressive funnels peace.
Xiaozhai Tianken (another name is Sky Pit) is the deepest sinkhole in the world, located in China. Its depth is 660 m, width is 530. This unique place is one of the most popular among tourists. It is especially interesting to visit it during the rainy seasons, due to the fact that during this period, amazingly beautiful waterfalls flow into it from the edges of this unimaginably large funnel.
To better represent the scale of this natural pit, it is often compared to a Boeing 747.
Dean's Blue Hole
The types of karst funnels are very diverse by the nature of their formation. The deepest sea funnel (202 meters) is the Blue Hole (almost 2 times deeper than other blue holes in Caribbean formed in a limestone cavity). It is located in the Bahamas.
Almost round in shape, the hole on the surface has a diameter of approximately 25-35 meters. From a depth of 20 meters, it noticeably expands, forming a cave with a diameter of one hundred meters.
In general, there are several similar water-filled karst pits. There are also deeper ones among them: Sunset in Mexico (335 m) and Pozzo del Merro (392 meters) in Italy. But Dean's Blue Hole is the deepest of all known karst voids filled with water, with entrances to them located below ur. seas.
Sima Humboldt, Venezuela
This is a unique karst funnel. Its depth reaches 320 meters. But its peculiarity is that the walls of Sima Humboldt are almost vertical, and therefore a special ecosystem has formed inside this karst formation.
Unusual plants grow there and unique animals live there, which you will not find anywhere else.
Darvaza, Turkmenistan
The funnel, which bears another rather terrible name (“Gates of Hell”), is about 60 meters in diameter, and its depth is approximately 30 meters.
15. Large blue hole part of the Belize barrier reef. Its diameter is 305 meters and its depth is 120 meters. Initially, this formation was a system of caves formed during the Ice Age. When the ocean rose, the roof of the flooded cave collapsed and this sinkhole formed. The explorer Jacques Yves Cousteau included it in the list of the top 10 dive sites in the world. Divers may encounter several interesting views fish, including giant groupers, nurse sharks and several types of reef sharks. During high tides, real whirlpools form in the place of the great blue hole, in which people often die. 14. The Udachnaya pipe is an active diamond deposit in the north of Yakutia, 20 kilometers from the Arctic Circle. Mining began in 1982. This is the largest diamond deposit in Russia in terms of raw materials and ore body size. The Alexander Pushkin diamond weighing 320 carats was mined here, and more recently a stone containing 30,000 diamonds was discovered, which is a million times more than their usual concentration. The depth of the quarry is 640 meters, and the length on the surface is 2 km. 13. The Kola superdeep well is the most deep well in the world. Its depth is 12262 meters, and the temperature at the bottom is 220 degrees. Celsius. The well was laid in 1970 to study the deep structure of the earth. The well served as the source of the urban legend of the "well to hell". Allegedly, on the approach to the 13th kilometer, the instruments recorded a strange noise coming from the bowels of the planet - the yellow newspapers unanimously assured that only the cries of sinners from the underworld could sound like this. In 2008, due to financial difficulties, the well was abandoned and the equipment was dismantled. 12. Deluxe Mystery Hole is a hole in the ground that has become an attraction in Oregon. According to the owner of the hole, this is the most interesting archaeological site in the state. Its depth has not yet been determined by modern scientific methods, but the fact is that it is very deep. Some say it was dug by ancient people, others say aliens. The owner of the hole, Pastor Barron, claims that the hole is already 5,000 years old and if you go down into it even a little, then you will find success in finances and personal life. 11. Devil's Funnel is a huge underground cave 15 meters wide and 106 meters deep, located in the state of Texas. Visitors are not allowed to descend into the cave, but in the summer you can see more than 3 million bats flying out of it at night. 10. In 2010, in Guatemala, right in broad daylight, a three-story garment factory collapsed into the ground along with a nearby residential building. Yes, it didn’t just fail, but disappeared into a huge hole, the bottom of which is visible only from a helicopter. This is not the first sinkhole in Guatemala. In 2007, there was formed similar crater 150 meters deep. Geologists can't explain how the black hole came to be so perfectly shaped, but locals are convinced that the city's dilapidated sewer system was the cause of the failure. 9. Over the past three decades, more than 3 thousand sinkholes have appeared in the dry parts of the ever-shrinking Dead Sea, while in 1990 there were only 40. There are more and more crevices, which means that the Dead Sea continues to die. His coastline shrinking by about a meter per year. In many respects, irrational irrigation in relation to the Jordan River, which feeds the Dead Sea, and the excessive extraction of the resources of the sea itself due to the increase in the population of the countries of the Middle East, are to blame here. The less salt water is in the sea, the easier it is for fresh underground sources to dissolve salt and destroy the usual landscape of the Dead Sea. 8. Diamond mining in the Mir deposit in Yakutia began in 1957. The quarry has a depth of 525 m and a diameter of 1.2 km. Mining of diamondiferous kimberlite ore by open pit was stopped in June 2001. Since 2009, diamond ore has been mined only at underground mine"World". Its capacity is 1 million tons of ore per year. In 2013, the mine produced over 2 million carats of diamonds. 7. In Siberia, scientists find more and more new giant craters of unknown origin. According to one version, the depressions were formed by explosions of methane accumulated underground, according to another, as a result of the melting of underground glaciers due to the previously established abnormal heat in the region. So far, scientists have discovered seven craters, but in their opinion there are more than 30 craters in total. 6. The Harwood Hole is a cave located in the southern part of New Zealand. On the surface, its diameter is 50 meters, and as it dives, it reaches 183 meters. Total depth The Harwood Hole is 357 meters high. Since its exploration in 1959, the cave has remained the deepest in New Zealand for many years. 5. The Monticello Dam is known for its original spillway design, in the form giant funnel called "Glory Hole". In the middle of Lake Berryessa, a large concrete pipe is installed, into which streams of water flow into a huge hole. From the side it may seem that the water, forming a giant funnel, merges into the very bowels of the earth. It is worth admiring the funnel during the rainy season, since the drain does not occur constantly, but only when the water level in Bariesse rises high enough. Previously, the site of the dam was the city of Monticello, which was flooded and created an artificial lake Berryessa. 4. Dean's Blue Hole is the deepest known blue hole on the planet. Its depth is 202 meters. The hole is located on Long Island in the Bahamas. This karst sinkhole is the training base for the Vertical Blue freediving team led by World Champion William Trubridge. On December 16, 2010, in Dean's Blue Hole, he reached a depth of 101 m, becoming the first person to overcome a depth of 100 m without the use of fins. 3. Bingham Canyon is a mining site in the Western United States, one of the largest quarries in the world, where a giant open pit copper deposit is being mined. Copper ore was first discovered here in 1850, and quarrying began in 1863, which continues to this day. About 1,400 people work at a quarry more than a kilometer deep and 4 km wide, who extract about 450 thousand tons of rock every day. 2. Another blue hole in the Bahamas, Sawmill Sink, is of greater scientific importance than Dean's blue hole. This sinkhole has been an archaeological site that has helped scientists change their perspectives on what the earth was like around 1,000 years ago. Interestingly, this hole was once dry, but gradually began to fill with water. The remains of birds, a giant tortoise and a crocodile that swam here have been preserved. The researchers also found the remains of one of the very first inhabitants of the Bahamas, who is already about 1050 years old. 1. This huge karst sinkhole is called the Heavenly Pit in China. Formed 128 thousand years ago, this funnel is the deepest in the world, its depth is as much as 662 meters. Due to its huge size, it is a favorite place for extreme skydiving. At the bottom of the funnel flows underground river 8 and a half kilometers long. During the rainy season, you can watch a beautiful view of the waterfall.
Our planet is like a huge gift bag: no matter how much you dig in it, you can always find something new. The Earth constantly presents researchers with surprises, and this has been happening for a very long time. A perfect example is the phenomenon of sinkholes that regularly form all over the world.
Cheese with holes, or about the precariousness of being...
Man has known about the existence of massive underground voids since time immemorial. It is quite natural that in old times they were associated exclusively with the machinations of evil spirits, people in every way avoided those places where their regular education took place. Holes from karst funnels were considered gates to the underworld.
Centuries passed, man mastered various sciences. Gradually, geologists revealed the secret of these natural formations. So. Underground voids are formed in those places where the rocks lying in the depths of the earth are highly susceptible to water erosion. When water seeps through the soil layer, it gradually erodes the same limestone, resulting in an underground cavity. Often, even majestic ones are formed in the depths of the earth, which for centuries remain unattainable for man.
You probably know at least one of the world-famous underground caves, no matter how strange it may sound, but these are all the same caste voids. In some areas of the earth, the layer of rock under the soil in terms of the number of holes can successfully compete even with Swiss cheese. Since collapses of the soil layer constantly occur in these parts, a rather peculiar landscape of the area is formed, which is called the "karst relief".
Since ancient times, people have treated such places with the greatest reverence, as they considered them to be the abode of Gods and spirits. In principle, they can be understood: when looking at others, landscapes of distant planets immediately come to mind ...
What is karst from a scientific point of view
By the way, do you know where the term “Karst” came from? And this definition went from the name of the area in northern Italy, Krasa (Karsta). Similar natural phenomena observed in many places in Slovenia and Croatia.
From a scientific point of view, it is a set of geological processes and phenomena. You should know that the occurrence of sinkholes is possible only in areas where the corresponding types of rocks occur (which we have already discussed above).
Important! Professional geologists often distinguish pseudokarst. This term refers to the formation of voids in the soil and underlying rocks. The difference from the "true" karst is that they were formed as a result of natural processes other than dissolution. For example, caves that appear after mudflows or the passage of a lava flow fall under this definition. We also do not forget about the voids that appear as a result of human activity and oil).
We will now talk about such phenomena. The most famous is one "Latin American" sinkhole. Guatemala is the city where she appeared.
Latin America
It was the last day of May 2010 outside. By Central America tropical storm Agatha rushed at full speed, destroying everything in its path along the way. In the morning, everything was quiet, and in the capital of Guatemala, utilities began to engage in restoration work. Suddenly, a huge funnel formed at a busy intersection, the diameter of which was 18 meters, and the depth reached 60 meters. A three-story residential building and a one-story outbuilding instantly fell into a huge one.
Oddly enough, but for Guatemala this event was not something from the category of incredible: just three years earlier, just a few kilometers from the city, a sinkhole was also formed, the depth of which was one hundred meters. Unfortunately, in both cases there were no human casualties.
What was it
Immediately after the incident, everyone assumed that everything happened as a result of the formation of sinkholes. But geologists quickly figured out that the city stands on dense volcanic pumice, which simply cannot physically be washed out. How did it happen that a giant cavity formed in a layer of dense geological rock?
Oddly enough, but careless utilities were to blame for everything. Due to the constant accidents and breakthroughs of sewer pipes that were laid in ancient times, a real underground network foul-smelling sewage rivers. Their "waters" eroded and dissolved the pumice, which soon began to wash away at a staggering rate. As a result, a huge cavity gradually formed in the thickness of the soil.
Rain is not always good...
In May 2010, the situation was further aggravated due to the gigantic amount of rainwater brought by Agata. Subsequently, the researchers found that in some places "karst" lakes were formed, which are still filled with a mixture of rainwater and sewage. Needless to say, how badly such "seas" affect the epidemiological situation throughout the city.
Thus, the case described by us is not a sinkhole. Guatemala is one of those few areas on Earth where their formation is in principle excluded. In general, earth sinkholes are often observed all over the world. Often their dimensions are really impressive: the diameter of the funnel can reach several tens of meters, not to mention a depth of a couple of hundred meters.
Because of what the frequency of their formation increases
Despite education, in many regions these natural phenomena continue to be considered something supernatural to this day. And people can be understood: it seems incredible that a solid and stable firmament under their feet can turn into a grandiose failure in a couple of seconds, in which even houses of several floors disappear. The situation is getting worse every year, and therefore people's anxiety is growing.
Experts say that the fault of almost every second karst failure lies with the person himself. The fact is that people overload the surface of the earth giant buildings, as well as extremely negatively affect the balance of groundwater. Due to human activity, their level is constantly decreasing, and therefore the risk of failures increases significantly.
Anthropogenic factor
The clearest example of the fact that even a huge karst basin can arise through the fault of a person is West Florida, USA. You will laugh, but in the same 2010, a sinkhole of impressive size appeared at the local landfill. Local geologists almost turned gray, because according to the conclusions of experts (dated in 1980), this area was absolutely stable (which is why it was chosen for a landfill).
Everything was explained simply: just under that place there was a channel. Since that year was dry, the water from it was intensively pumped out throughout the state. The result is failure.
In America alone, the annual damage caused by failures is estimated at 10-15 billion (!) Dollars.
Oddly enough, but sometimes karst landforms can serve a person as an excellent service. The fact is that such places are usually extremely beautiful. An ideal example is the numerous sinkholes in the forests of Indonesia, as well as the majestic Great Blue Hole, which is located off the coast of Belize.
Irrational use of soil water
In many ways, the root of all evil lies in the fact that humanity is extremely irrationally using the most valuable resource of soil and groundwater. Of course, it is difficult to get away from this: moisture is the most valuable resource, and with the development of world agriculture, it is used in increasing volumes. Groundwater is pumped out everywhere to irrigate agricultural land, and somewhere to this day they use the disastrous practice of draining swamps, which leads to increasingly unfavorable consequences. Thus, in many countries there is already a shortage of drinking water.
Until recently, only science fiction writers wrote about the coming wars for her, and today quite “mundane”, pragmatic specialists are talking about the same thing.
German misadventures
We emphasize once again that karst voids are quite natural phenomena. In the same 2010 (it was a turbulent time), the quiet and calm German town of Schmalkalden in Thuringia twice discussed an incredible event. On a quiet November morning (November 1st) right in the middle central street a huge crater with a diameter of 40 meters was formed, the depth of which immediately reached 20 meters. As soon as the passions subsided, on November 11, the same thing happened in the same place.
Right on the border with the old crater, a new one formed, taking several garages with it. local residents. Since the earth collapsed at night, it was possible to avoid human casualties.
"Hell's Gate"
Relatively recently, it became known that the crevices of the hills, which are located in the Turkmen desert of the Karakum, contain a considerable amount of natural gases. More precisely, it was possible to find out about this only in 1971. At that time, near the small village of Darvaz, drillers were making another well. During this fascinating process, they got straight into the karst underground cavity with a drill. It had gas in it. So many.
The drilling rig almost immediately collapsed into the resulting cavern, the diameter of which was 20 meters and the depth - all 60 meters. Fortunately, there were no casualties, but gas began to come out of the ground. Since its composition posed a danger to the lives of people and animals, they decided to set it on fire. Experts assumed that gas reserves would soon burn out. Alas, they have been burning for more than four decades.
Since the word "Darvaz" in the local dialect means "gate", local population expectedly dubbed the surreal landscape "the gates of hell."
Not every failure is a karst
It is not surprising that in last years intensive research is underway in the field of preventive detection of dangerous underground cavities. So, the famous Israeli geologist Lev Eppelbaum from the University of Tel Aviv is busy studying the failures around Dead Sea with the help of their colleagues from Jordan and France. It must be said that the sea it represents is truly unique natural object. And the point is not only in the amazing salinity of its waters, but also in the fact that this reservoir is located 415 meters below sea level.
Its salinity is extremely high for the simple reason that water evaporates very intensively from the surface of the sea, a sufficient volume of which simply does not have time to bring. In addition, the channel of the latter is getting shallower every year, as the needs of Israel and Jordan's agriculture are growing. Accordingly, the level of the Dead Sea is also decreasing (by approximately one meter per year). So how does all this relate to the topic of the article?
salt dips
It's simple: along the entire coast of the Dead Sea, at a depth of 25 to 50 meters, huge deposits of salt are hidden. Previously, these places were under a layer of salt water, but now it has receded. As a result, fresh ground water begins to come into contact with the salt lumps. As a result - a kind of "karst" areas, densely dotted with failures. As you might guess, the latter arise due to the erosion of salt with water.
To date, the number of caverns, the diameter of which varies from a meter to 30 meters, is estimated at several thousand. From the air, the region is increasingly beginning to resemble the surface of the moon. And the situation is getting worse: in the eight decades during which people have observed the level of the Dead Sea, it has decreased by 20 meters.
How can you fix the situation
The situation can be saved only by increased inflow of water from the Jordan River. Unfortunately, one can only dream of such a thing, since intensively developing agriculture needs more and more of it. Experts talk about the possibility of digging a channel from the Red Sea. This possibility has been talked about for a long time, so there is a possibility that it will someday be made. In the meantime, geologists are testing new methods and tests that allow residents to be warned in advance coastal areas about the danger of sudden subsidence of the soil.
Thus, karst origin has not every failure in the ground. However, regardless of their origin, each of these pits is potentially dangerous due to the possibility of its subsequent sharp growth.
Funnels invariably attract researchers and tourists. Although exploring the largest of the karst formations can be extremely dangerous, people are not put off by this.
Sinks are one of the most incredible landforms. They are formed due to the movement of soil in karst, that is, water-soluble rocks. When groundwater dissolves and leaches rock layers, the earth sags - and a funnel appears. The depth of some does not exceed a meter, others go underground for tens and hundreds of meters.
1. - karst lake, which filled a deep 530-meter funnel in southern Croatia. Formed as a result of the collapse of the arch of a large underground cave. There is a theory that this lake It is connected by underground streams with all other lakes and rivers of its region.
2. The total depth of the funnel is approximately 530 meters, and its volume is approximately 25-30 million cubic meters. Thus, it is one of the largest sinkholes in the world.
3. - a relatively small funnel, about 30 meters deep, but its bottom is filled with crystal clean water. Of course, it immediately turned into a magnet for tourists.
4. The depth of the Bimma well is about 20 meters. Under water there is a tunnel 500 meters long, which connects the sinkhole with the sea and fresh water here it mixes with the sea.
5., which is also called the "Gates of Hell" - a funnel with a diameter of 70 meters and a depth of , located in Turkmenistan. Soviet geologists set fire to a natural gas pit back in 1971, hoping that it would burn out in a couple of days. The flame has not subsided so far.
6. The diameter of the crater is approximately 60 meters, the depth is about 20 meters. Gas comes from underground, splitting into hundreds of burning torches of different sizes. In some torches, flames reach 10-15 meters in height. Clickable:
8. - a funnel in Venezuela about 320 meters deep with almost vertical walls. It is named after the German scientist and traveler Alexander von Humboldt. The forest grows abundantly not only around the funnel, but also inside it.
9. An almost circular sinkhole falls to a depth of 314 meters, and the volume of the funnel is 18 million cubic meters. The upper edge of the failure is 352 meters wide, and at the bottom it reaches 502 meters. Thanks to the vertical walls, a unique ecosystem has developed at the bottom of the funnel, with such species of plants and animals that are not found anywhere else on Earth.
10., she is the Heavenly Pit, the deepest karst funnel in the world - 660 meters deep and 530 wide. One of the most popular places for tourism in China. It is advised to visit during the seasons heavy rains, because then beautiful waterfalls flow inward from the edges of the funnel.
11. For scale: Sky Pit and Boeing 747.
12. - an underwater karst funnel of almost perfect round shape, 120 meters deep and 300 meters in diameter. Discovered by the famous explorer Jacques-Yves Cousteau, who included it in the list of 10 the best places for diving.
13. This geological formation was originally a system of limestone caves formed during the last ice age. The sea level was then much lower, but when the ocean rose and the arch of the flooded cave collapsed, a sinkhole formed.
During high tides, real whirlpools form at the site of the great blue hole, drawing in everything floating on the surface: algae, boards, boats. Often people die in these whirlpools. With the onset of low tide, the hole begins to spew out powerful fountains of water.
Landfalls are really scary. In addition to the dangers that lie in wait for us on the surface of the earth or above it, the earth itself can suddenly slip out from under our feet, swallowing us along with a house or vehicle.
What are sinkholes and how do they form? These are literally holes formed by subsidence of the earth due to a combination of three factors: water, erosion and time. Flowing groundwater percolates through granular soil, rocks, sand in the topsoil, and even through grains of the underlying bedrock.
If the bedrock is made up of something like gypsum, limestone, or dolomite, water can simply erode it, dissolving the loose deposits. In the case of continuous or repeated exposure to water, these rocks can form large holes or even extensive systems caves. High acidity of the water, for example due to absorption of carbon dioxide, can greatly speed up the process.
Water-eroded bedrock splits, eroding deeper layers of sedimentary rock. In addition, it happens that water first destroys the internal bedrock and then, making a hole, rises to the overlying (topmost) layer of the earth. Once the overburden has been eroded from the bedrock area, the continuation of the process depends on the type of soil.
If the overburden is loose sand, bottom particles will be washed away or sink through depressions or cracks in the bedrock. The loose layers above will follow, causing the entire overburden to plummet down to fill the void.
This can happen quickly or slowly depending on the rate of erosion of the bedrock. As a result, a karst funnel can make its way up to them. Such dips are called settling. Much more dramatic are the cases where the overburden consists of clay. Since clay sticks together much more easily than sandy soil, it does not all drain into the hole in the bedrock.
Instead, the flow of water constantly erodes the lower part of the clay layer, forming a large karst void that rises closer and closer to the surface. When the remaining layer can no longer resist gravity, it falls into the abyss below it. If there is a residential building or a salon full of valuable cars on this place, then the owners will have to say goodbye to property, and maybe to life. Such dangerous funnels are called failing.
On video from american state Louisiana, coastal trees are shown falling due to a hole that has formed under the water. Scientists are fairly well aware of which areas are most prone to sinkholes. Based on geological studies, this is characteristic of karst landforms and “vulnerable” rocks (salt and gypsum).
One of the hallmarks of an area where sinkholes are likely to occur is extensive cave systems carved into the bedrock. NASA recently announced that they can use radar data from satellites to track the movement of the ground and detect sinkholes at the preliminary stage.
