The pattern keeps repeating.

News about another mass shooting breaks and transfixes the nation. Full of outrage – about gun violence, mental health care, video games, the president or whatever they believe is at the root of the crisis – Americans take to Twitter.

On social networks, they share their grief, their frustration and their calls for action. Until, inevitably, they stop.

Just how long does the conversation last? About 10 days.

Using data from the social media monitoring source Crowd Tangle, USA TODAY analyzed online discussions after America’s most deadly mass shootings of the past decade. The analysis focused on tweets containing the words "mass shooting" and the location of each incident in the 10 days after a shooting.

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On the day of an incident and in the few days immediately following, conversations are frequent on social media. Within a week to 10 days, the message volume rapidly declines, plummeting to a tiny fraction of what it was.

After the massacre in 2017 at a country music festival in Las Vegas, in which 58 people were killed, the tweet volume decreased by more than 70% the day after the shooting.

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The drop-off was slightly less drastic, but still present, after the Sandy Hook shooting in Newtown, Connecticut – when 27 people, most of them very young children, perished. Tweets decreased by more than 60% the day after that shooting and remained level for the next four days.

Among America's deadliest shootings, the only one to deviate from the pattern was the high school massacre in Parkland, Florida. Almost immediately after the incident, survivors became outspoken proponents for gun control, organizing activist events such as the March for Our Lives. Data shows that online conversations about Parkland increased considerably for several days after the shooting.

In the wake of back-to-back mass shootings in El Paso, Texas, and Dayton, Ohio, data suggests the discussion has declined. Online discourse was elevated for a few days after the shooting, but within 10 days, it was as low as ever.

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Experts said this doesn't mean the tragedies don't have a lasting impact on the public. In fact, social media discussion about gun control has steadily increased in the past five years, according to Crowd Tangle data.

Paul Levinson, a professor of communication and media studies at Fordham University, said the window of opportunity to harness public sentiment to enact change is narrow. Despite nine of America's 10 deadliest shootings happening in the past five years, and growing online interest in gun control, little has been achieved legislatively. The Parkland shooting's deviance from the typical pattern is evidence that a concerted effort can at least keep the conversation going.

"Activists need to do both: act quickly on social media, but also continuously and unrelentingly over time," Levinson said.

For Levinson, it isn’t surprising that people so enthusiastically take to Twitter after a tragedy. Social media provides an instant, easy space to organize and create a call to action, he said.

After the Sandy Hook shooting, outrage on social media led to the founding of Sandy Hook Promise, a gun control organization with a membership that rivals the National Rifle Association.

Topics rise and fall quickly on social media. It’s human nature to move on, Levinson said. For most people, including politicians, gun violence is not the primary concern in a country facing a host of other issues.

“We all have short attention spans,” Levinson said. “Within a couple days, something else takes our interest.”

Wynter Mitchell-Rorbaugh, a digital strategist who works with brands to improve social media reach and engagement, said cutting through the “noise” online is a constant struggle for everyone, including gun control movements in the wake of a mass shooting. Distractions are inevitable, Mitchell-Rorbaugh said, and they come from every direction.

“I don’t think people are necessarily moving on,” Mitchell-Rorbaugh said. “They’re couching it for the next time this happens.”

Levinson said the drop-off of social media messages isn’t as important as the initial spark of interest. Though most people will move on and stop tweeting about gun violence, many will stay focused on the topic for years, forming nonprofit and lobbying groups, making it their life’s work. Each time another shooting happens, social media allows that group to grow.

“Communication is always better than noncommunication,” Levinson said. “Talking is better than being silent.”

Tracing tweets about "gun reform" and "gun control" with Crowd Tangle, USA TODAY found the conversations becoming more common since 2015. Messages may dissipate after each individual shooting, but conversations about gun control have increased by more than 6,000% overall in the past four years.