The truth about quicksand

Death from subsidence in sand or swamp is the scenario commonly used in movies, but the reality is not quite the same.

According to the BBC, the familiar scene is a person stuck in quicksand, asking for help around, the more struggling, the deeper it subsides. In the end, it was swallowed by sand. This motif appears many times in movies.

However, the evidence that you will get stuck and die in wet quicksand is quite small . Wet quicksand usually consists of sand, or clay and salt that are submerged, often in the delta. The surface looks like a hard substrate, but when you step in, the sand will liquefy.

Sand and water splits, leaving a wet sand pit like a trap. Friction between the grains of sand will be greatly reduced and cannot be balanced with body weight and you will begin to sink. It is true that the more you struggle, the deeper you will sink, but it is true that you will be completely sunk.

Wet sand

Daniel Bonn, a professor at the University of Amsterdam, Netherlands, sampled soil from an Iranian lake that warned of quicksand with visitors bringing it to the lab. After analyzing the ratio of sand, salt water and clay, he created quicksand to simulate experiments.

He uses aluminum particles, which have the same mass as humans in the experiment. After placing aluminum particles on quicksand, he shook the whole model to simulate human struggles.

Scene falls into quicksand in a movie.(Photo: AF Archive / Alamy).

As a result, the aluminum particles are indeed submerged at first, but then, the sand gradually mixes with the water, the thrust of the mixture increases and the aluminum particles are pushed to the surface. Bonn and his team continued to place other objects on quicksand, those with the same mass as humans actually sink, but only half sink.

If physics says that you will not drown in quicksand, why there are often fatal accidents happening, like the drowned mother and daughter in 2012 while on vacation in Antigua, the eastern island of West Ocean?

The reason is that if you can't get out of the situation in the quicksand, the tide may submerge you. This is the real danger of wet quicksand.

However, it is difficult to get rid of that situation alone. According to Bonn's research, a force of 100,000 Newtons is required to liberate one foot - the equivalent of lifting a medium-sized car.

In the laboratory, Bonn's team discovered that salt is a basic component of wet quicksand, which increases the instability of sand, leading to the formation of dangerous, thick sediment areas.

However, another team from Switzerland and Brazil discovered a new type of quicksand without salt. They examined the geological samples collected in a lagoon of northeastern Brazil.

They found that the bacteria made a shell on the top of the soil, giving the impression of a stable surface, but when it entered, the surface collapsed. Fortunately, these areas are quite shallow compared to the height of a person so it is not dangerous.

Dry sand

Dry quicksand is a completely different matter.Falling into a dry quicksand can be deadly.

In 2002, a case of dry quicksand was reported. A man fell into a grain storehouse on a farm in Germany. At the time of the firefighter's discovery, he had sunk to the armpit exactly as it was in the film, and continued to sink. Whenever the victim breathes out, the chest is deflated and grains of grain are pressed in, making breathing more difficult.

A doctor had to pass an oxygen supply tube to the victim and place a saddle around his chest. However, after that, the victim suffered from chest pain, while the doctor suffered from asthma attacks. Firefighters then had to use a cylinder, slip under the victim and suck the grains out with an industrial vacuum pump to save the man.

To survive if you fall into a place of dry quicksand, you need help outside as quickly as possible. If it's wet sand, you're stuck, not sinking. To exit you need to move your feet a little, so that the water and sand around your feet mix. Need to be calm, lean back and try to distribute your body weight evenly, wait patiently until you emerge.