Numerous earthquakes centered in Irving shook North Texas Tuesday. Hitting a magnitude high of 3.6, the quakes left minimal damage but have been felt throughout the Metroplex. For an area not used to earthquakes, there was some uncertainty regarding what exactly had happened.

“My thought was that it was a big truck on the highway because my office faces I-35E so it sounded like something was driving into the building, so my co-worker and I both held onto our desks waiting for something to hit,” Child Protective Services employee Kim Higgins said.

The biggest of the tremors hit mid-afternoon and once it had subsided, area residents were able to figure out what it was.

“When the noise stopped everything was still shaky,” Higgins said. “Everyone ran out of our offices into the common area and everybody was saying ‘earthquake, earthquake.’ It took me about an hour for my nerves to calm down.”

Initial reports indicate the earthquakes took place along the Balcones Fault Line that runs through central Texas.

According to The Dallas Morning News researchers from SMU are looking into the recent rise of quakes in the Irving area as there have been some 50 quakes in the region since November 2008.

“The bottom line is: We don’t know why the frequency is increasing,” Irving’s city manager, Chris Hillman told the Dallas Morning News. “We have a history of quakes, but we’re interested in getting as good an understanding why the increase in frequency is occurring. How long it will take to study is something we don’t now. It could take months. It’s not something we’re expecting to know it days or weeks. This much is certain: We understand residents’ concerns and are being very proactive to do all we can to get an understanding. They expect and need more understanding. At the city we’re not seismologists, so we’re going to rely on the folks who really do know what they’re doing.”