The formation of karst funnels. What is a karst fault?

Our planet looks like a huge bag with gifts: how much it does not dig, you can always find something new. The Earth constantly presents researchers with surprises, and this has been happening for a very long time. An ideal example is the phenomenon of karst funnels, which are regularly formed around the world.

Cheese with holes, or the fragility of being ...

The man knew about the existence of massive underground voids from time immemorial. It is only natural that in ancient times they were associated exclusively with the machinations of evil spirits, people in every possible way eschewed the places where their regular education took place. Holes from karst funnels were considered to be the gates to the underworld.

There were centuries, a man mastered a variety of sciences. Gradually, geologists discovered the secret of these natural formations. So. Underground voids are formed in those places where the rocks lying deep in the earth are highly prone to water erosion. When water seeps through the soil layer, it gradually erodes the same limestone, resulting in the formation of an underground cavity. Often in the depths of the earth even majestic karst lakes are formed, which for centuries remain unattainable for man.

You probably know at least one of the world's famous underground cave with stalactites and stalagmites: strange as it may sound, it's all the same caste emptiness. In some areas of the earth, a layer of rock under the soil in terms of the number of holes can compete successfully even with Swiss cheese. Since in these parts of the continual collapse of the soil layer, a rather peculiar terrain of the terrain is formed, which is called "karst relief".

For a long time people treated such places with the greatest respect, since they considered them the abodes of Gods and spirits. In principle, they can be understood: when looking at other forms of relief, the minds 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 the north of Italy, Kras (Karst). Similar natural phenomena are observed in many places in Slovenia and Croatia.

From a scientific point of view, this is a combination of geological processes and phenomena. It is necessary to know that the emergence of karst funnels is possible only in the area where the corresponding types of rocks lie (which we mentioned above).

Important! Professional geologists often distinguish pseudo-karst. This term refers to the formation of voids in the soil and the underlying rocks. The difference from the "true" karst is that they were formed as a result of other natural processes than dissolution. For example, under this definition, caves that arise after the descent of mudflows or the passage of a lava flow completely fall. Do not forget also about the emptiness that appears as a result of human activity (the extraction of gas and oil).

We will now describe these phenomena. The most famous is one "Latin American" karst funnel. Guatemala is the city where it appeared.

Latin America

In the courtyard was the last day of May 2010. In Central America, "all the pairs" carried a tropical storm "Agatha", incidentally destroying everything in its path. In the morning everything was quiet, and in the capital of Guatemala, the municipal services began to engage in rehabilitation work. Suddenly a huge funnel was formed at the busy intersection, the diameter of which was 18 meters, and the depth reached 60 meters. In a huge karst failure, a three-story apartment house and a one-storey wing immediately fell through.

Strangely enough, for Guatemala this event was not something of an unbelievable level: just three years before that, just a few kilometers from the city, a dip was also formed, the depth of which was a hundred meters. Unfortunately, in both cases, there were human casualties.

What was it

Immediately after the incident, everyone assumed that everything happened as a result of the formation of karst craters. But geologists quickly clarified that the city is on a dense volcanic pumice stone, which simply can not be physically blurred. How did it happen that a giant cavity formed in the layer of dense geological rock?

Strangely enough, but everything was to blame ... careless utilities. Because of the constant accidents and breakthroughs of sewer pipes, which were laid in immemorial times, a real underground network of foul-smelling sewage rivers formed under the city. Their "water" blurred and dissolved the pumice stone, which soon began to wash away with stunning speed. As a result, a huge cavity gradually formed in the soil.

Rains are not always useful ...

In May 2010, the situation became even more aggravated due to the huge 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. It is not necessary to say how bad such "seas" influence the epidemiological situation in the whole city.

Thus, the case described by us is not a karst funnel. Guatemala refers to those few areas on Earth where their education is in principle excluded. In general, earth dips are often observed all over the world. Often their sizes are really impressive: the diameter of the funnel can reach several tens of meters, not to mention the depth of a couple of hundred meters.

Because of what the frequency of their formation grows

Despite education, in many regions, these natural phenomena still continue to be considered something supernatural. And people can be understood: it seems incredible that a firm and stable firmament under your feet can turn into a grand failure in a couple of seconds, in which even houses on several floors disappear. The situation is aggravated every year, and that is why people's anxiety is growing.

Experts say that the fault almost for every second karst failure lies on the person himself. The fact is that people overload the surface of the earth with giant buildings, and also extremely negatively affect the groundwater balance. Because of 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 hollow can arise through human fault is West Florida, USA. You will still laugh, but in the same year 2010 a local dump experienced a spectacular failure. Local geologists almost turned gray, as according to expert opinions (dated 1980), this area was absolutely stable (why it was chosen for dumping).

It was explained simply: just below that place was the channel of the underground river. Since that year was arid, the water from it was intensively pumped all over the state. As a result, failure.

Only in one America, the annual damage caused by the failures is estimated at 10-15 billion (!) Dollars.

Strangely enough, but sometimes the karst forms of relief can serve a man excellent service. The fact is that such places are unusually beautiful, as usual. An ideal example can serve as numerous karst funnels in the forests of Indonesia, as well as the majestic Great Blue Hole, which is located near 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, this makes it difficult to leave: moisture is a very valuable resource, and with the development of world agriculture it is used in ever larger volumes. Urban water is pumped everywhere for irrigation of agricultural land, and somewhere to this day they use the disastrous practice of draining swamps, which leads to increasingly unfavorable consequences. So, in many countries there is already a shortage of drinking water.

Until recently, only the science fiction writers wrote about the coming wars for it, and today they are already talking about quite "mundane", pragmatic experts.

German miscarriages

Once again, we emphasize that karst voids are quite natural phenomena. In the same year 2010 (restless time), the quiet and peaceful German town of Schmalkalden in Thuringia twice discussed an incredible event. On a quiet November morning (November 1st), right across the central street, a huge crater 40 meters in diameter formed, the depth of which reached at once 20 meters. Only the passions had subsided, as on 11 November the same happened in the same place.

Right on the border with the old crater, a new one was formed, taking with it several garages of local residents. Since the earth collapsed at night, human casualties were avoided.

"Hell Gates"

More recently it became known that in the fissures of the hills that are located in the Turkmen desert of Karakum, there is a considerable amount of natural gases. More precisely, it was only in 1971 that we learned about this. At that time, near the small village of Darvaz, drillers were making another well. During this fascinating process, they fell straight into the karst underground cavity. There was gas in it. Lots of.

The drilling rig almost immediately collapsed into a formed cavern, the diameter of which was 20 meters, and the depth - all 60 meters. Fortunately, there were no casualties, but gas began to escape from under the earth. Since its composition posed a danger to the lives of people and animals, it was decided to set it on fire. Specialists 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 "gates", the local population has dubbed the surreal landscape "the gates of hell".

Not every failure is karst

It is not surprising that in recent years intensive research has been carried out in the field of preventive detection of dangerous underground cavities. So, the well-known Israeli geologist Lev Eppelbaum from the University in Tel Aviv is busy studying the failures around the Dead Sea, using the help of his colleagues from Jordan and France. It must be said that the sea is a truly unique natural object. And it's 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 from the sea surface evaporates very intensely, the amount of which the Jordan River simply does not have enough time to bring. In addition, the channel of the latter melts ever more every year, as the needs of the agriculture of Israel and Jordan are growing. Accordingly, the level of the Dead Sea decreases (approximately one meter per year). So how does all this relate to the topic of the article?

Salt Failures

It's simple: along the entire coast of the Dead Sea, at a depth of 25 to 50 meters, huge deposits of salt hide. Previously, these places were under a layer of salt water, but now it has receded. As a result, ground fresh water begins to come in contact with the lumps of salt. As a result - a kind of "karst" areas, densely punctuated by failures. As it is easy to guess, the latter arise from the erosion of salt with water.

To date, the number of caverns, whose diameter 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: during those eight decades, during which people observed the level of the Dead Sea, it fell by 20 meters.

How can I improve the situation?

The situation can only be saved by increasing the flow of water from the Jordan River. Unfortunately, this only has to be dreamed of, since intensively developing agriculture needs more and more of its volumes. Specialists talk about the possibility of digging a canal from the Red Sea. This possibility has been talked about for a long time, so there is a possibility that it will someday be done. In the meantime, geologists are testing new techniques and tests that can warn coastal residents about the danger of a sharp subsidence of the soil.

Thus, karst origin is far from every failure in the earth. However, regardless of their origin, each of these pits is potentially dangerous for the possibility of its subsequent sharp growth.