Until now, it could only be activated by Facebook staff.
Safety Check lets people notify their friends and family that they are safe in the aftermath of a natural disaster or human conflict in their area.
The recent earthquake in Italy marked the 25th time this year that it has been triggered.
Safety notifications have reached one billion people in 2016 alone, the firm said. In the previous two years combined (2014 and 2015) it had only been activated 11 times.
The Safety Check Facebook team uses three criteria to decide whether the tool should be switched on - how many human lives are affected, the extent of that impact and the duration of the event.
The tool itself is one simple button.
The Italy earthquake Safety Check page is no longer active
"Sometimes people on the ground know much better when this tool is relevant to them and their friends than we do," said Katherine Woo, product lead at Facebook.
"We are only able to bluntly target people in a broad city or broader region but the community will know which of their friends will be closer."
The tool was developed following the Japanese tsunami in 2011 and was initially restricted to natural disasters only. This changed after the Paris terrorist attacks last year.
During the community test trial, which began in June, one particular bombing in Baghdad triggered Safety Check.
"It was a case where even though it's an area that sees a lot of turmoil, this event was noteworthy enough," said Facebook software engineer Peter Cottle.
Facebook first aid
However, Facebook is clear that it is not able to provide physical assistance.
"We are not a first responder and we are not in the position to actually save people," said Ms Woo.
"Some people say we should have a 'mark not safe' button or an 'I need help' button - but we want to direct people to official local emergency numbers."
Colleagues Janet Robinson and Hugo Malim were having a drink together in London when the terrorist attack at the Bataclan, in Mr Malim's home city of Paris, occurred.
"As soon as I heard about the attacks, I posted a public update stating that I was safe and currently in London," he said.
"However, as I wasn't aware that Facebook was running the safety check, I didn't mark myself as 'safe' on the Friday. This created panic amongst some of my relatives with a cousin calling me on the Saturday to make sure I was fine."
"Once you have a group of friends that are accounted for you start to get more concerned about those who haven't checked in," said Ms Robinson.
Control
Janet Robinson, who used to live in Turkey, said she had used the tool during the terror attacks on the airport and in the city of Istanbul.
"Obviously the airport attack in Istanbul made the news internationally, but the one that worried me was the one on Istiklal street, which is the main shopping street. That made the news briefly but it worried me more because I knew that my friends were more likely to be in that area.
"But would that have been considered a significant event for Safety Check? I would quite like to have more control over it."
Mr Malim agrees.
"I feel that with these attacks happening globally, it would be easier to let users inform their relatives and friends that they are safe rather than wait for Facebook to trigger an application," he said.
BBC News