Eight people died during a crowd surge at Travis Scott's Astroworld festival in Houston on Friday.
Concertgoers may lose their moral compass in large crowds, a sociologist told Insider.
Fans may also have had pent-up stress and anxiety from nearly two years of social isolation.
A violent swell of fans killed eight people at Travis Scott's Astroworld Festival in Texas on Friday night. Crowd surges at concerts are rarely deadly - but there's a reason why they form, psychologists say.
A concert's energy can heighten people's emotions, causing to them to ignore their surroundings or safety risks. Larger crowds in particular may encourage people to "follow the herd" and rush the stage if people around them are doing so - even if they know that behavior is inadvisable.
But there was likely an additional factor at play during Friday's concert in Houston, according to Alexis Piquero, chair of the sociology department at the University of Miami: pent-up stress and anxiety from nearly two years of social isolation.
"In theory, we're getting out of this pandemic and people just need to let loose," Piquero told Insider.
In he future, he added, concert planners may need to account for this bottled-up energy when deciding how many people to admit, how much security to hire, and how to control the crowd.
"How do you do it in a way where you allow people to have a great time, to yell and scream at the top of their lungs to let loose, but do it in a safe way?" Piquero said, adding, "Let's use Houston, Astroworld, as an example of what didn't go right."
Concertgoers may lose their moral compass or sense of danger in large crowds
An estimated 50,000 people attended Astroworld. Around the time Travis Scott took the stage, concertgoers began to push against one another to reach the front, Houston Fire Chief Samuel Peña said in a news conference just after the event.
Some people were either knocked down or lost consciousness after not having enough room to breathe. The force of the crowd eventually trampled some fans on the ground. Eight people, all of them younger than 30, died. Two were teenagers.
Among the dozens of injured concertgoers, a 9-year-old boy, Ezra Blount, remains in critical condition. Blount's father, Treston, had been carrying his son on his shoulders when the crowd surged.
"He kept screaming, 'I can't breathe,'" Ezra's grandmother, Tericia, told Rolling Stone. "But everyone was pushing. It was so tight with no exits. His dad couldn't breathe at all and passed out. We don't really know what happened to Ezra after that."
Ezra's family later identified him at a nearby hospital, Rolling Stone reported.
Piquero said it's common for concertgoers to feel anonymous in large crowds, and therefore devoid of personal responsibility - a concept known as "deindividuation."
"There is an absolute direct link in the literature that crowd size leads to more feelings of - not necessarily impunity or invincibility - but you let your moral compass turn away for a second," he said.
So concertgoers mimic one another's behavior, even if that behavior is dangerous.
"When people are part of the collective, they're like, 'Well, if that person is doing it, I guess it's OK. And if I don't rush to the front, then someone else is going to have a better view, especially if I'm a short person,'" Piquero said.
Those factors combined, he added, can cause people to abandon their sense of risk in favor of the reward: in this case, getting closer to the stage.
Fans may have been eager to let loose because of the pandemic
Piquero said there's usually a perfect storm of issues that leads to a concert mob. In 2000, for instance, nine people died in a crowd surge during a Pearl Jam performance in Denmark. Heavy rain that day may have made the ground slippery, and potentially caused some fans to fall, Rolling Stone reported at the time. Sound issues with the venue's rear speakers may have also prompted concertgoers to push toward the stage.
In the case of Astroworld, Piquero said, post-lockdown anxiety and stress likely played a role.
"When you go to a concert, it's like going to a sporting event - you're going to forget about your boss, you're going to forget about your deadline," he said. "We're just going to go to escape from our world's problems, especially now as we're trying to come out of this 20-month crazy [period] that we've all been living in."
Fans may have felt pressure to let loose or reclaim a lost sense of freedom, he added.
"Here you have this one thing that everybody was looking forward to," Piquero said. "People are flying from all over the country, driving from all over. This guy's concerts are electric. He blends all kinds of music. He's a superstar. And everybody's looking forward to this beautiful night in Houston and then - a tragic event."