Last year, when University of Minnesota freshman Margaux Jensen was a senior at Waconia High School, some of her classmates heard that a student was heading out of town for vacation with his family. The response was classic teen rebellion, but with a modern twist: The high schoolers, who broke into the family's home and threw a raucous, house-trashing party, had gotten the vacation news via the student's Facebook feed.

Such "over-sharing" blunders are a worrisome byproduct of the rapidly increasingly prevalence of social media.

But recent geolocation technology such as Foursquare and Facebook's Places feature, which allow users to "check in" to an exact location on a map and see who else is there, are ratcheting up concerns that more abuse will occur, putting young people at risk.

"This new technology, it can be used for good -- finding friends in the same mall," said Cris Clapp Logan, communications director for Enough Is Enough, an Internet-awareness organization based in Virginia. "Or bad -- in the targeting of kids by a predator. Everyone just needs to be educated about it, and be smart."

These new location services are wildly popular with young people, who can use their mobile devices to track their friends' locations. The days of wondering where all the cool kids were hanging out are gone; these sites make it easy to get a mutual group of friends together, because you can see who else is checked in where you are.

"It's cool, people know exactly where you are," said Lakeville North junior Emi Kidder. "Now you know where everyone is hanging out. A lot of my friends are on it. It's getting popular."

To some, it may seem surprising that someone would release enough personal information to enable crimes against themselves. But Linda Criddle, president of the Safe Internet Alliance, said it happens all the time, spurred by the slow desensitizing of society to such self-leaks.

"Robberies have been happening through MySpace, LinkedIn, Facebook for years," she said. "It's just getting more popular. And Places is another manifestation. What makes it particularly dangerous, of course, is the number of members on Facebook."

First, she said, one gets accustomed to putting their names on retail websites, and then they add identifying information such as pictures on blogs and addresses on sites like Ebay and Craiglist. Now, with social networks multiplying, and organizations like Facebook becoming a real part of our digital lives, many have lost a sense of just how much of their personal lives are floating around out there. Suddenly, adding a mapped location to one's status doesn't seem like such a huge step.

"You know, they say if you put a frog in boiling water, it will jump out," Criddle said. "But if you put it in a pot and slowly heat the water around him, he'll get cooked."

Settings matter

Foursquare and Places have protections built in to address personal-safety concerns but experts say that getting them to the highest levels of protection can be a challenge and isn't always the first thing teens are thinking about.

Facebook said it has created a robust set of controls for people who want to use Places. "We made a great deal of educational material available to people, and we created step-by-step educational videos that walked people through how to control their information while using Places," said spokeswoman Nicky Jackson Colaco.

Indeed, users are able to control exactly how wide an audience their information may reach. The default settings, however, do not reflect the most conservative option available, which doesn't let anyone else see the user's location.

And since most users are unlikely to change their settings, the default is critical, said Loren Treveen, a professor at the University of Minnesota and an expert in social media.

With Foursquare, the concerns were muted because the networks grew with the application's distinct function (finding people via their geolocations) in mind. But when users engage in Places, their geolocation is automatically made public to their entire Facebook friend base unless they actively adjust their settings.

For many, that means that hundreds, even thousands of people -- many of whom they don't know very well -- can see their whereabouts. Another feature allows users who have checked in to a location to see every Facebook user also checked in to that place, regardless of their friend status, meaning that strangers can see your picture and information, and know where you are. That default is represented in a small, somewhat unclear box, and it is already enabled. Additionally, Places is the only geolocation service where other users are able to check you in. That aspect, however, must be manually enabled to work.

"Those are non-obvious ways that your privacy can be violated, and to change those things you have to go find the settings in two different places," Treveen said.

Kidder didn't touch her settings until her dad, concerned for her safety, sat down with her to go over the potential risks. "My first instinct is just: 'Ooh, this is cool.' I don't think about the settings," she said.

So far, Logan hasn't been made aware of any cyber bullying or stalking cases from Foursquare or Places. But that doesn't make her rest easier about the potential for misuse.

"As someone who has worked closely with the technology industry, with law enforcement, I realize putting all this information up can obviously help facilitate Internet-initiated crime," she said. "There have been a lot of lessons learned over the past couple years as far as protecting kids online."

Amelia Rayno • 612-673-4115