Why you should be worried about earthquakes if you live in OklahomaThe ground shook in Oklahoma Monday as seven earthquakes struck the state. The frequency of seismic activity in the state has been so high that it now outranks California for earthquakes of magnitude-3.0 or greater. Sandra Ladra experienced the strongest, a 5.6, that hit the town of Prague in 2011. Ladra told CBS News it was hard to believe what was happening at the time because she had never been in an earthquake like that before. A rock that fell from her fireplace injured her leg and shattered her sense of safety. “If you don’t feel safe in your home, what do you do?” Ladra said. Since late 2009, the U.S. Geological Survey found Oklahoma has had 300 times more earthquakes than in previous decades. The latest study says 300 million-year-old fault lines have been reactivated and are capable of producing a magnitude-6.0 quake. “The reason for the study is to identify regions most likely able to produce a magnitude 6.0 earthquake and how that may affect infrastructure in the buildings in the region,” said Dan McNamara with the U.S.G.S. FULL REPORT