Our planet looks like a huge bag with gifts: no matter how you dig in it, you can always find something new. Earth constantly presents surprises to researchers, and this has been happening for a very long time. An ideal example is the phenomenon of karst funnels that regularly form around the world.
Cheese with holes, or the precariousness of being …
Man has known about the existence of massive underground voids from time immemorial. It is quite natural that in ancient times they were associated exclusively with machinations of evil spirits, people in every possible way avoided those places where their regular education took place. Holes from karst craters were considered gates to the underworld.
Centuries passed, man mastered a variety of sciences. Gradually, geologists revealed the secret of these natural formations. So. Underground voids are formed in those places where rocks lying deep in 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 in the depths of the earth even majestic karst lakes are formed, which for centuries remain unattainable for humans.
You probably know at least one of the world-famous underground cave with stalactites and stalagmites: 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 soil collapse is constantly occurring in these parts, a rather peculiar landscape of the area is formed, which is called the “karst relief”.
For a long time people treated such places with the greatest reverence, since they considered them to be the abode of Gods and spirits. In principle, they can be understood: when you look at other forms of relief, landscapes of distant planets immediately come to mind …
What is karst scientifically
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, Krasus (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. You should be aware that the occurrence of karst funnels is possible only in the area where the corresponding types of rocks occur (of which we have already mentioned above).
Important! Professional geologists often distinguish pseudo-karst. This term refers to the formation of voids in the soil and underlying rocks beneath it. The difference from the “true” karst is that they were formed as a result of natural processes other than dissolution. For example, caves that arise after mudflows or the passage of a lava flow completely fall under this definition. Do not forget about the voids that appear as a result of human activity (gas and oil production).
We will now talk about such phenomena. The most famous is one "Latin American" karst funnel. Guatemala is the city where it appeared.
Latin America
It was the last day of May 2010 in the yard. Across Central America, the Agatha tropical storm swept in full steam, simultaneously destroying everything in its path. In the morning, everything calmed down, and in the capital of Guatemala, public 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. In a huge karst failure, a three-story residential building and a one-story outbuilding instantly fell through.
Oddly enough, for Guatemala this event was not something incredible: just three years before that, just a few kilometers from the city, a failure had also formed, the depth of which was one hundred meters. Unfortunately, in both cases, there were some casualties.
What was it
Immediately after the incident, everyone assumed that everything happened as a result of the formation of karst funnels. But geologists quickly made it clear that the city stands on a dense volcanic pumice stone, which simply cannot be physically washed out. How did it happen that a giant cavity was formed in a layer of dense geological rock?
Oddly enough, they were to blame for everything … negligent utilities. Due to the constant accidents and breakthroughs of sewer pipes that were laid back in time immemorial, a real underground network of foul-smelling sewage rivers was formed under the city. Their "water" was washed away and dissolved pumice, which soon began to wash out at a stunning speed. As a result, a huge cavity gradually formed in the thickness of the soil.
Rains are not always useful …
In May 2010, the current situation was further aggravated by the gigantic amount of rainwater brought by Agatha. Researchers subsequently found that karst lakes formed in some places, 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 we have described is not a karst funnel. Guatemala belongs to those few areas on Earth where their formation is, in principle, excluded. In general, earth dips 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 the depth of a couple of hundred meters.
Because of what the frequency of their formation is growing
Despite their education, in many regions these natural phenomena are still considered to be something supernatural. And people can be understood: it seems incredible that a solid and stable firmness underfoot can turn into a grandiose failure in a couple of seconds, in which even houses on several floors disappear. The situation is aggravated every year, and therefore the anxiety of people is growing.
Experts say that almost every second karst failure lies with the person himself. The fact is that people overload the surface of the earth with giant buildings, and also have an extremely negative effect on 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 occur due to human fault is West Florida, USA. You will still laugh, but in the same 2010 at a local landfill there was a failure of an impressive size. Local geologists almost turned gray, because according to experts (dated 1980), this area was absolutely stable (which is why it was chosen for landfill).
The explanation was simple: just under that place was the bed of an underground river. Since that year was a dry year, water was intensively pumped out of it throughout the state. The result is a 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 excellent service. The fact is that, as usual, such places are extremely beautiful. Numerous karst craters in the forests of Indonesia, as well as the majestic Great Blue Hole, which is located off the coast of Belize, can serve as an ideal example.
Irrational use of soil water
In many ways, the root of all evils 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 a most valuable resource, and with the development of world agriculture it is used in ever larger volumes. Groundwater is pumped everywhere for irrigation of agricultural land, and somewhere to this day they use the disastrous practice of draining bogs, which leads to more and more adverse consequences. So, in many countries there is already a shortage of drinking water.
Until recently, only science fiction writers wrote about impending wars for it, but today quite “mundane”, pragmatic experts are talking about the same thing.
German misadventures
We emphasize once again that karst voids are quite natural phenomena. In the same 2010 (the time was turbulent), the quiet and calm German town of Schmalkalden in Thuringia twice discussed an incredible event. On a quiet November morning (November 1), in the middle of the main street, a huge crater with a diameter of 40 meters formed, the depth of which reached immediately 20 meters. As soon as the passions died down, on November 11 the same thing happened in the same place.
Right on the border with the old crater, a new one was formed, taking several garages of local residents. Since the earth collapsed at night, human casualties were avoided.
Hell's Gates
More recently, it became known that in the crevices of the highlands located in the Turkmen desert of Karakum, a considerable amount of natural gases is contained. More precisely, it was possible to find out only in 1971. At that time, near the small village of Darvaz, the drillers were making another well. During this fascinating process, they got into the karst underground cavity with a drill straight. There was gas in it. Lots of.
The drilling rig collapsed almost immediately into the formed cavity, the diameter of which was 20 meters, and the depth was all 60 meters. Fortunately, there were no injured, but gas began to escape from the ground. Since its composition was a danger to the lives of people and animals, they decided to set it on fire. Experts suggested that gas reserves would burn out soon. Alas, they have been burning for over four decades now.
Since the word “Darvaz” in the local dialect means “gates”, the local population expectedly dubbed the surreal landscape “the gates of hell”.
Not every failure is karst
It is not surprising that in recent years there has been intensive research in the field of preventive detection of hazardous underground cavities. So, the famous Israeli geologist Lev Eppelbaum from the University of Tel Aviv is studying the dips around the Dead Sea, using the help of his colleagues from Jordan and France. I must say that the sea is a truly unique natural site. And the point is not only in the amazing salinity of its waters, but also in the fact that this body of water is located 415 meters below sea level.
Its salinity is extremely high for the simple reason that water very intensively evaporates from the surface of the sea, the sufficient volume of which the Jordan River simply does not have time to bring. In addition, the channel of the latter becomes shallower every year, as the needs of agriculture in Israel and Jordan are growing. Accordingly, the level of the Dead Sea is also declining (by about one meter per year). So how does all this relate to the topic of the article?
Salt dips
It's simple: along the coast of the Dead Sea, at a depth of 25 to 50 meters, huge deposits of salt are hiding. Previously, these places were under a layer of salt water, but now it has receded. As a result, fresh groundwater begins to come into contact with blocks of salt. 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 by water.
Today, 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 resembling the surface of the moon. And the situation is getting worse: over the eight decades during which people watched the level of the Dead Sea, it fell by 20 meters.
