Here’s what causes crowd crushes like the deadly one in Seoul

On Saturday — in what appears to be one of the deadliest disasters in South Korea since 2014 — at least 150 people were killed in a crowd crush during Halloween celebrations in Seoul’s Itaewon, the first large-scale partying for the holiday since the pandemic began.

The event can be described as a crowd crush or surge, but not a stampede, said G. Keith Still, a crowd safety expert and visiting professor of crowd science at the University of Suffolk in England. A crush or surge happens when people are packed together in a confined space and there’s movement such as pushing that causes the crowd to fall over. Essentially, Still said, a “domino effect.”