article_snippet.sent: 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.
article_snippet.sent: Earthquakes, Earthquakes 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.
article_snippet.sent: The study identified 17 areas in the central and eastern US with increased rates of induced seismicity.
article_snippet.sent: Since 2000, several of 17 areas in the central and eastern US have experienced high levels of seismicity.
article_snippet.sent: Researchers say there have been 'substantial increases since 2009 that continue today' Researchers said the spike in seismic activity was largely down to the oil and gas industry injecting wastewater deep underground, which can activate dormant faults.
article_snippet.sent: 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. '
article_snippet.sent: A 2014 United States National Seismic Hazard Maps with the areas most at risk shown in warmer colours.
article_snippet.sent: The cumulative number of earthquakes with a magnitude of 3.0 or larger in the central and eastern US, 1973-2014.
article_snippet.sent: The rate of earthquakes began to increase starting around 2009 and accelerated in 2013-2014 .
article_snippet.sent: 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.
article_snippet.sent: Increases in the number of tremors from 1960-2010 shown in various regions of the US.  
article_snippet.sent: A group of experts met last year in Oklahoma to pinpoint seismic hotspots around the country caused by induced quakes.
article_snippet.sent: Scientists initially identified 14 regions affected by quakes linked to drilling.
article_snippet.sent: The findings were released at a Seismological Society of America meeting in Pasadena, California.
article_snippet.sent: 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.
article_snippet.sent: Researchers study man-made quakes in the affected areas to determine how often Researchers are expected to occur in the next year and how much shaking Researchers would produce.
article_snippet.sent: A series of earthquakes that rattled a small Texan community have been linked to nearby oil and gas operations.
article_snippet.sent: 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 .