article: More than a dozen areas in the US have been shaken by small earthquakes triggered by oil and gas drilling, according to a government report released today. The man-made quakes jolted once stable regions in eight states, including parts of Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma and Texas. Earthquakes, they said, were sometimes caused by fracking, in which large volumes of water, sand and chemicals are pumped into rock formations to free oil or gas. Scroll down for video . The study identified 17 areas in the central and eastern US with increased rates of induced seismicity. Since 2000, several of these areas have experienced high levels of seismicity. Researchers say there have been 'substantial increases since 2009 that continue today' They said the spike in seismic activity was largely down to the oil and gas industry injecting wastewater deep underground, which can activate dormant faults. Many studies have linked the rise in small quakes to the injection of wastewater into disposal wells, but the Geological Survey's report takes the first comprehensive look at where the man-made quakes are occurring. 'The hazard is high in these areas,' said Mark Petersen, who leads the agency's national mapping project. Oklahoma lately has been rocked by more magnitude-3 quakes than California, the most seismically active of the Lower 48 states, Petersen said. Oklahoma was not on scientists' radar until recently when the state experienced a spate of quakes, the largest registering a magnitude-5.6 in 2011. A 2014 United States National Seismic Hazard Maps with the areas most at risk shown in warmer colours. Recently, man-made quakes jolted once stable regions in eight states, including parts of Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma and Texas . The cumulative number of earthquakes with a magnitude of 3.0 or larger in the central and eastern US, 1973-2014. The rate of earthquakes began to increase starting around 2009 and accelerated in 2013-2014 . Earlier this week, the Oklahoma Geological Survey acknowledged that it is very likely most of the recent shaking is from wastewater disposal. Many faults awakened by drilling have not moved in millions of years, Geological Survey geophysicist William Ellsworth said. 'They're ancient faults,' Ellsworth said. 'We don't always know where they are.' A message to the American Petroleum Institute was not immediately returned. The industry group has said efforts are made to map fault lines where drilling occurs. The fluid pressure in the pores and fractures of the rocks is called the 'pore pressure.' The pore pressure acts against the weight of the rock and the forces holding the rock together. If the pore pressures are low - especially compared to the forces holding the rock together - then only the imbalance of natural in situ earth stresses will cause an occasional earthquake. If, however, pore pressures increase, then it would take less of an imbalance of in situ stresses to cause an earthquake. This type of failure is called shear failure. Injecting fluids into the subsurface is one way of increasing the pore pressure and causing faults and fractures to 'fail' more easily. Earthquakes can be caused by injecting fluid into the subsurface or by extracting fluids at a rate that causes subsidence and slippage along planes of weakness in the Earth. Source: US Department of Energy . Increases in the number of tremors from 1960-2010 shown in various regions of the US.  Scientists said it's difficult to know what jobs will trigger shaking . A group of experts met last year in Oklahoma to pinpoint seismic hotspots around the country caused by induced quakes. Scientists initially identified 14 regions affected by quakes linked to drilling. They later added three other high-risk areas - northern Oklahoma-southern Kansas; Greeley, Colorado; and Azle, Texas. The findings were released at a Seismological Society of America meeting in Pasadena, California. Seismic hazard maps produced by the Geological Survey and used for building codes and insurance purposes don't include quakes caused by the oil and gas industry. Scientists said it's difficult to know what jobs will trigger shaking. Researchers study man-made quakes in the affected areas to determine how often they are expected to occur in the next year and how much shaking they would produce. A series of earthquakes that rattled a small Texan community have been linked to nearby oil and gas operations. In this image red squares are injector locations; pink arrows, approximate location of two large brine production wells that are located both near the faults and near reported earthquakes swarms .
highlights: Man-made quakes have hit once stable regions in central and eastern US .
  These include Arkansas, Colorado, Kansas, Ohio, Oklahoma and Texas .
  Some were caused by injection of wastewater which can activate faults .
  Many of faults awakened by drilling have not moved in millions of years .
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