Twitter users may be inadvertently revealing their location through updates on the social media site, according to a new analysis that sampled more than 15 million tweets.
Twitter has approximately 500 million active users, who are expected to tweet 72 billion times in 2013, researchers said.
Reports have shown that about 6 per cent of users opt-in to allow the platform to broadcast their location with every tweet.
But that's only part of the footprint Twitter users leave, and even users who have not opted-in for location tagging may be inadvertently revealing where they are, the study shows.
"There are all sorts of information that can be gleaned from things outside of the tweet itself," said lead author Chris Weidemann, from the University of Southern California.
To get a fuller sense of what publicly accessible data might reveal about Twitter users, Weidemann developed an application called Twitter2GIS, to analyse the metadata collected by Twitter, including details about the user's hometown, time zone and language.
The data, generated by Twitter users and available through Twitter's application programming interface (API) and Google's Geocoding API, was then processed by a software programme, which mapped and analysed the data, searching for trends.
During the one-week sampling period of the study, roughly 20 per cent of the tweets collected showed the user's location to an accuracy of street level or better.
Many Twitter users divulged their physical location directly through active location monitoring or Global Positioning System (GPS) coordinates.
But another 2.2 per cent of all tweets - equating to about 4.4 million tweets a day - provided so-called "ambient" location data, where the user might not be aware that they are divulging their location.
"The downside is that mining this kind of information can also provide opportunities for criminal misuse of data," Weidemann said.
"My intent is to educate social media users and inform the public about their privacy," said Weidemann.
The study was published in the International Journal of Geoinformatics.