The truth about quicksand

Dying by sinking in the sand or swamp is a scenario often used in movies, but the reality is not quite like that.

According to BBC, the familiar scene is a person trapped in quicksand, calling for help around, the more he struggles, the deeper he sinks. In the end, it was swallowed up by the sand. This motif appears many times in movies.

However, the evidence that you will get stuck and die in wet quicksand is quite scant . Wet quicksand usually consists of sand, or clay, and submerged salt, usually in deltas. The surface looks like a hard foundation, but when you step on it, the sand will liquefy.

The sand and water split, leaving a wet sand pit like a trap. The friction between the sand grains will be greatly reduced and cannot balance with your body weight and you will begin to sink. It is true that the more you struggle, the deeper you will sink, but is it true that you will sink completely.

Daniel Bonn, a professor at the University of Amsterdam in the Netherlands, took a soil sample from a lake in Iran with a quicksand warning for visitors to bring back to the lab. After analyzing the ratio of sand, salt water and clay, he created quicksand for simulation experiments.

He used aluminum beads, which have a density similar to that of humans in the experiment. After placing aluminum beads on quicksand, he shook the entire model to simulate human struggle.

The truth about quicksand
Falling into quicksand in a movie. (Photo: AF Archive/Alamy).

As a result, the aluminum particles do sink at first, but after that, the sand gradually mixes with the water, the repulsion of the mixture increases and the aluminum particles are pushed to the surface. Bonn and his team continued to place other objects on top of quicksand, objects with the same density as humans do indeed sink, but only half.

If physics says you won’t drown in quicksand, why do fatal accidents happen all the time, like a mother and daughter drowned in 2012 while on vacation in Antigua, an island in the east of the Atlantic Ocean? Positive?

That’s because if you can’t get out of the quicksand soon, the high tide could drown you. This is the real danger of wet quicksand.

However, it is very difficult to get out of that situation alone. According to Bonn’s research, it takes a force of 100,000 Newtons to free one leg – the equivalent of lifting a midsize car.

In the lab, Bonn’s team discovered that salt is a fundamental component of wet quicksand, which increases the instability of the sand, leading to the formation of dangerously thick deposits.

However, another team from Switzerland and Brazil discovered a new type of quicksand that doesn’t contain salt. They examined geological samples obtained in a coastal lagoon in northeastern Brazil.

They found the bacteria had formed a crust on top of the soil, giving the impression of a stable surface, but upon entering the surface collapsed. Luckily these areas are quite shallow for a person’s height so it’s not dangerous.

Dry quicksand is another matter entirely. Falling into an area of dry quicksand can be fatal.

In 2002, a dry quicksand accident was reported. A man fell into a grain warehouse on a farm in Germany. By the time firefighters found him, he had sunk to his armpits just like in the movies, and was still sinking. Each time the victim exhales, the chest collapses and the grains press in, making breathing increasingly difficult.

A doctor had to thread an oxygen tube to the victim and put a saddle around his chest. However, after that, the victim suffered from chest pain, and the doctor suffered an asthma attack due to dust. Firefighters then had to use a cylinder, threaded under the victim and sucked out the grains with an industrial vacuum pump to save the man’s life.

To survive if you fall into a dry quicksand, you need outside help as quickly as possible. If it’s wet quicksand, you’re just stuck, not fully submerged. To get out, you need to move your feet a little, so that the water and sand around your feet mix together. You need to be very calm, lean back and try to evenly distribute your weight, patiently waiting for you to rise.