News of a possible explosion rippled through the popular online service Twitter on Tuesday, in a preview of what’s to come in the realm of breaking news and citizen journalism. Twitter is a so-called microblogging site that allows users to send and receive short messages.

At about 1:37 pm, software developer Dave Winer asked the Twitterverse: “Explosion in Falls Church, VA?” (Perhaps not coincidentally, Winer is a well-known blogger and podcasting evangelist). A flurry of posts, or “tweets,” followed, as users reported rumbles as far away as Alexandria.

The mainstream media entered the fray at 2:33 pm, with radio station WTOP reporting ground rumblings throughout Northern Virginia, citing a possible earthquake. Officials also told the radio station that the rumblings were part of construction blasts at nearby Ft. Belvoir, which had been scheduled for later in the afternoon as part of a new building for the National Geospatial Intelligence Agency.

Twitter users continued to pile on, pointing out data from the Maryland Geological Survey and adding their own commentary. Twitterer DataG wrote: “After the ‘Falls Church explosion’ event that was covered on Twitter, I saw the value in having a Twitter account at-the-ready.”

By 2:56 pm — nearly 90 minutes after Winer’s initial alert — WTOP had the official word from the U.S. Geological Survey: A not-exactly-massive 1.8 magnitude earthquake with an epicenter near Annandale, VA.

The “Falls Church Incident” was earthshaking only in the most literal sense, but it is an interesting proof of concept that news can be broken on Twitter. Reuters is looking at ways to use Twitter in the newsroom, although our feed is currently under renovation.