The collapses of the holes on the beach make sharks more victims. Because they happen, what physics says and how to prevent an often ignored danger.
Days ago, you will have learned, a boy died in beach in Montalto di Castro (Viterbo) while digging, according to some reconstructions, a tunnel within one hole Over one and a half meter deep. There sand He collapsed on him, trapping him and causing death by suffocation.
The event may seem rare, but it is not at all. “The hole in beach I am much more dangerous Of how much people imagine, “warns Stephen Leatherman, professor of environmental sciences at Florida International University. There sandexplained Leatherman to the NBC American TV network after a similar case in the United States, “collapses without notice and, if it takes place around bust or to the headit is almost impossible to free the victim in time ».
They cause more victims the holes that sharks
Between 1990 and 2006, they recorded in the United States 16 deaths caused by collapsed sand holes. In the same period, the Mortal attacks of sharks were 12. A difference that surprises, if we consider how much media attention is unbalanced towards sharks and not towards the dangers – much more frequent – tied to sand.
In Italy there are still no official statistics on these accidents, but some cases ended up in the chronicles: in 2010 an Italian child died in the Canaries in similar circumstances, and other episodes also occurred in Viareggio and on the Romagna Riviera.
Sand physics: how a hole collapses
When it is damp there sand behaves like a material cohesivein which the surface tension of the water between the grains holds the latter together, making the sand maintain its shape. But when the sand herself dries, especially on the lateral walls of the deep holes, loses stability. It takes little to trigger the collapse: the weight of the edge, one person that is on purpose, one vibration.
A cube meter of dry sand it can weigh between 1,400 and 1,600 kg. Even just half a cube meter, in case of collapse, is equivalent to the weight of a small car that “presses” on a person’s chest. If the collapse takes place on face or chest, the victim can die from asphyxiation in less than three minutes.
The psychological trap: because we underestimate the risk
Dig hock on the beach is a family gesture, seen as a pastime “innocent”. Precisely for this reason it is underestimated. The beaches are associated with Relaxal game and freedom, and ours perception of risk drops drastically.
Even attentive parents often do not grasp the danger until it is too late.
The lack of signs informationclear rules and awareness campaigns contributes to the problem. Rarely in the bathing establishments they are found indications that explicitly discourage it excavation Of hole deepindications that would instead be useful also to prevent the risk – less serious from the point of view of the consequences but although exempire significant – of the accidental fall of distracted bathers.
