The aftermath of the Astroworld Festival incident that left nine people dead in Houston last week is raising concerns about how footage and misinformation related to the event is being circulated on social media.

Videos showing people being crushed and unconscious circulated on TikTok, Twitter Inc. and other platforms. “Travis Scott concert” was one of the most searched terms on Google on Saturday, the day after the incident, according to Google Trends data.

On...

The aftermath of the Astroworld Festival incident that left nine people dead in Houston last week is raising concerns about how footage and misinformation related to the event is being circulated on social media.

Videos showing people being crushed and unconscious circulated on TikTok, Twitter Inc. and other platforms. “Travis Scott concert” was one of the most searched terms on Google on Saturday, the day after the incident, according to Google Trends data.

On TikTok, videos using the hashtag #Astroworld had about 2.4 billion views as of Thursday.

And more than 400,000 tweets have mentioned either Travis Scott or the festival by name since the event on Nov. 5, according to an analysis by Storyful, a social-media research firm, which is owned by News Corp, the parent company of The Wall Street Journal.

Conspiracy theories, including that the concert was part of a satanic ritual, also became prevalent. Tweets mentioning satanism more than tripled from Nov. 7 through Nov. 9 compared with the three-day period beforehand, according to the Storyful analysis.

Travis Scott couldn’t see or hear what was happening in the crowd at the Astroworld Festival in Houston on Friday, his lawyers said.

Photo: Amy Harris/Associated Press

The proliferation of graphic or questionable content on people’s feeds puts the spotlight on how social-media companies police their platforms. These companies have invested heavily in artificial-intelligence systems designed to detect problematic content, and have hired thousands of moderators to review content. But it is often difficult to administer which videos cross the line, adding to the complexity these companies face.

At the same time, social-media algorithms generally reward content that has been viewed, liked or shared many times, allowing content to go viral. They present content on topics to users based on biographical data as well as previous content they have consumed and interacted with on the platform.

Therefore, extreme or divisive content often becomes amplified, regardless of its validity, said Scott Campbell, a telecommunications professor at the University of Michigan.

“Extremity carries capital,” he said. “It’s what gets clicks, shares, comments.”

And regulating content—whether it’s misinformation or graphic images—often presents a practical challenge. “The social-media gatekeepers can’t totally weed it out, it’s impossible,” Mr. Campbell said.

Eight people died and many were injured at the Astroworld Festival in Houston Friday. Officials said the crowd began to compress toward the stage during Travis Scott’s performance, but the causes of death weren’t immediately known. Photo: Erika Goldring/WireImage The Wall Street Journal Interactive Edition

Unfiltered content from tragic events can have significant psychological consequences on users and people featured in the content. A University of California study published after the 2013 Boston Marathon bombing found that media exposure can trigger acute stress following a traumatic event.

“We’re getting a deeper taste into what kind of trauma can be captured and shared, and this incident is an example of that and how psychologically shattering it can be for some people,” Mr. Campbell said.

Social-media companies say they are monitoring the situation, and posts or videos that violate policies around graphic content have been removed.

A TikTok spokeswoman said conspiracies surrounding the Astroworld Festival are in violation of the social-media platform’s community guidelines and will be removed. Several videos promoting conspiracy theories, some with hundreds of thousands of views, were available to view Thursday. A TikTok representative didn’t respond to requests for comment regarding those videos.

YouTube, a unit of Alphabet Inc.’s Google, hasn’t found videos related to the Astroworld Festival that violate its policies, a spokesman said Thursday, but the company continues to monitor the situation. YouTube policies prohibit footage of corpses or blood with the intent to shock or disgust viewers.

A memorial outside the Astroworld Festival site in Houston.

Photo: thomas shea/Agence France-Presse/Getty Images

“As we do during evolving news events, our systems are prominently surfacing videos from authoritative news sources in search and recommendations and limiting the spread of borderline content,” the spokesman said. He added that the platform was displaying news and surfacing fact-checking information about Astroworld around its videos.

Twitter didn’t respond to requests for comment.

A spokeswoman for Meta Platforms Inc., Facebook’s parent company, didn’t respond to questions pertaining to content from Astroworld. She said the platform removes videos and photos that show the violent death of someone when a family member requests their removal. The social-media company’s policies call for the removal of content that glorifies violence or celebrates the suffering of others.

“We allow graphic content (with some limitations) to help people raise awareness about these issues,” Facebook’s violent and graphic content policy states. “We add a warning label to especially graphic or violent content so that it is not available to people under the age of 18 and so people are aware of the graphic or violent nature before they click to see it.”

Mr. Scott’s lawyers say the rapper didn’t know what was happening in the crowd of more than 50,000 fans at his show. While it appeared like Mr. Scott performed a full set, “when he was told to stop, he stopped—and it was an abbreviated set,” said David Byrnes, one of Mr. Scott’s lawyers. Mr. Scott learned of the police’s declaration of a mass casualty incident and the deaths early the next morning, his lawyers said.

User videos uploaded to social-media platforms can also aid police investigations when incidents happen. “Not only do we have the [camera] infrastructure set up by event organizers, we have thousands of humans carrying that infrastructure in their pockets,” said Mr. Campbell, the professor at the University of Michigan.

Houston Police Department spokespeople declined to answer questions from the Journal relating to social media’s role in the department’s investigation.

Lee Humphreys, a communications professor at Cornell University, says it’s important for social-media companies to flag graphic content to users.

“It’s a relatively easier solution than just censoring it all together, which I don’t think is necessarily appropriate,” she said.

Write to Omar Abdel-Baqui at Omar.Abdel-Baqui@wsj.com