Some areas are known to be more earthquake prone than others because they lie on major fault lines such as the San Andreas Fault in California, and the Madrid Fault in Missouri, or the Wasatch Fault in Utah. (rmiia.org)
Not only can earthquakes have an impact far beyond major fault lines, some areas of the country — notably, parts of Oklahoma — are experiencing more seismic activity as a result of oil drilling efforts. (iii.org)
Iran sits astride major fault lines and is prone to frequent tremors. (fortune.com)