The U.S. Geological Survey (UGCS) have warned that up to 7 million American citizens are at risk from both natural and “induced” earthquakes, caused by fracking. UGCS published an earthquake hazard map showing the areas where Americans are most at risk. Washingtonpost.com reports: The list of places at highest risk of man-made earthquakes includes Oklahoma, Kansas, Texas, Arkansas, Colorado, New Mexico, Ohio and Alabama. Most of these earthquakes are relatively small, in the range of magnitude 3, but some have been more powerful, including a magnitude 5.6 earthquake in 2011 in Oklahoma that was linked to wastewater injection. Scientists said Monday they do not know if there is an upper limit on the magnitude of induced earthquakes and that this is an area of active research. It’s not immediately clear whether this new research will change industry practices, or even whether it will surprise anyone in the areas of newly estimated risk. In Oklahoma, for example, the natural rate of earthquakes is only one or two a year, but there have been hundreds since fracking and horizontal drilling, with the associated wastewater injection, became commonplace in the last decade. “By including human-induced events, our assessment of earthquake hazards has significantly [...]