Human-induced earthquakes cause less shaking than tectonic ones

Nature : Although the injection of wastewater into the ground by hydraulic fracturing and other drilling projects has been known to cause earthquakes, the quakes tend to induce less shaking than natural quakes of the same magnitude, according to a recent study published in the Bulletin of the Seismological Society of America. One reason may be that the fluids injected into the ground “lubricate geological faults and allow them to slip more smoothly,” according to the paper’s author, Susan Hough of the US Geological Survey. Hough studied both manmade and natural earthquakes and compared the reported magnitude with what people said they felt. However, the finding only holds true for areas more than 10 km from the quake’s epicenter. The research may prompt restrictions on the location of such drilling efforts to keep them away from populated areas.