Seismic activity detected in April and May near Blackpool, England are now attributed to a nearby gas well operated by Cuadrilla Resources, and the hydraulic fracturing process that is carried out there. Hydraulic fracturing, or "fracking", is a controversial technique that involves pumping a mixture of water, sand, and chemicals deep underground. The pressurized slurry cracks a rock layer, releasing natural gas that is then pumped to the surface.
Fracturing operations were suspended on May 27th of this year, however Cuadrilla states that the tremors were due to a rare synergy between the operation and the local geology. They maintain that such conditions are unlikely to happen again at future well sites.
The two tremors in the spring measured 1.9 and 2.8 on the Richter scale. Such quakes are barely felt by any population above ground, therefore virtually no property damage is observed. However, residents and environmentalists are concerned that some of the chemicals used in fracturing could seep into the local groundwater and affect water quality. A counterargument by the natural gas industry claims that the procedure has been performed safely in various countries for decades.
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Sources:
http://www.google.com/hostednews/ap/article/ALeqM5he6vNxUO2yKEmHzpETyJCkzSOpDA?docId=e693d4d7cf124ace81058acb201ef505
http://news.discovery.com/earth/gas-well-caused-earthquake-111104.html
Image:
Hydraulic fracturing operation (Wikimedia Commons)