How Peaceful Crowds Turn Into a Deadly Crush

The more than 150 people who died celebrating Halloween in Itaewon, a dense neighborhood in Seoul, were victims of a crowd crush. The disaster was not a stampede; it wasn’t the result of unruly behavior or people trampling over one another. Instead, it was a tragedy in which the massive number of people packed into an alley turned the crowd itself into a hazard.

Crowds don’t need to surge for the gathering to turn deadly—smaller movements and pushes by those on the outer edges can send currents through the group that grow in strength, creating a domino effect. Eventually, the pressure on people’s bodies turns suffocating. “They’ll not have done anything deliberately. It’s very difficult when you’re in a crowd to know that it’s dangerous,” says Martyn Amos, a professor at Northumbria University who studies crowds.

These types of disasters have been documented for decades at sporting events, concerts, and nightclubs, most recently in October when 135 died following a football match in Indonesia, and when 10 perished at the Astroworld music festival in Houston, Texas, in 2021. Experts say crushes are preventable but can occur due to the failings of authorities and organizers—and Amos thinks this is the case in Seoul, as well. “People were the medium through which the disaster occurred, but the root cause of this incident seems to be in a lack of preparation from the authorities,” he says.

How Crushes Happen

Amos says safe crowds act like a gas; people are like particles that can move around freely. But add too many people—about five or six for every square meter—and the crowd transforms to become more like a liquid. “Where the crowd is a fluid, that’s where we’ve got the potential for problems,” he says. “You’re essentially a particle at the mercy of physics.”

A small push from the back of the crowd can grow stronger as it ripples through the group like a wave. If it eventually reaches a person next to an obstruction, like a wall, fence, or immovable pack of people, that wave has nowhere to go. Without an outlet, that force can now crush the people in its path. In the Itaewon incident, a collapse in the crowd may have caused the obstruction, with one or more people falling in the densely packed group. And when people are trapped, Amos says, the force of the crowd can hem them in and prevent others from pulling them out.

Ultimately, people die in crowd crushes from asphyxiation, Amos says. When a person breathes out, their chest cavity contracts. But when they try to breathe in again, the force of people around them can be too strong, making it impossible for their chest to expand and take in new air. Five people pushing on one person can create a 3,000-newton force, says Amos, or the equivalent of 674 pounds, which can break a person’s ribs.

Take the 1989 Hillsborough disaster, a crush that resulted in 97 deaths at Hillsborough Stadium in England. The strength of the crowd broke steel barriers, a feat that required forces on them to exceed 4,500 newtons, Amos says. Gil Fried, an attorney and professor at the University of West Florida with an expertise in crowd management, says metal railings were also twisted after a 1993 incident at the University of Wisconsin-Madison’s Camp Randall Stadium. That destruction was the result of more than 1,000 pounds of pressure per square inch.

The US Centers for Disease Control and Prevention offers recommendations for surviving a crowd crush. One is to take a boxer’s stance, with feet apart and knees slightly bent, one in front of the other, and hands up. This may keep people from falling or having their arms pinned. Another is to move with the flow of the crowd instead of against it. Experts also encourage people not to waste breath screaming, and they caution against bending over to pick up dropped items.

But there’s little else individuals can do to protect themselves once the crowd’s pressure builds. Those on the outer edges of a crowd often have no idea their movements are crushing others in the group.

Preventing the Next Crush

Most crowded concerts and events are safe, thanks to advance planning from organizers. It’s typically a lack of proper safety planning that exposes crowds to danger. In Seoul, the blame has fallen on local police, who, according to The Washington Post, received calls about large crowds hours before the crush but did not disperse people from the area. South Korean prime minister Han Duck-soo said officials lacked a “crowd management system” and has called for a fix to the issue. “The government is responsible for lives and safety of the people, and it is our absolute duty.”

After the deaths at Astroworld, the organizers faced lawsuits over allegations that inadequate security and planning led to as many as 5,000 injuries. A human rights organization in Indonesia claims tear gas used by police triggered the panic at the stadium there, with people crushed to death trying to reach the only remaining exit.

Solutions for crowd crush are largely preemptive, says Fried. Venues should have a sufficient number of trained crowd managers, who are different from crowd control experts. Crowd control responds when an emergency occurs, but crowd managers plan in advance and monitor events. Crowd managers should also have ways to communicate with the attendees to direct behavior, whether on loudspeakers or via signs like scoreboards. Often, when people push from the back of the crowd and start to exert pressure on people in the middle or those pressed against barriers, they have no idea others are getting hurt. Clear instructions that address the whole crowd and get them to move can help.

At organized events, venues and planners spend money on risk assessments and simulations, planning for emergencies. But the Seoul disaster was an unticketed event in a public space, and police did not effectively plan for the large crowds, as investigating authorities have said. “The best prevention is the planning to make sure this doesn’t happen,” says Fried. “Once it happens, it is very difficult to stop it.”

How Peaceful Crowds Turn Into a Deadly Crush

(May require free registration to view)