Natural gas hydraulic fracturing consists to make more gas flow for extraction by injecting a mixture of sand, water, and some chemicals into rocks The quantity of gas increases, because the fluid used to fracture rocks is high pressurized, so it creates more ways for the gas to flow.The technique of fracturing can also be used for oil.
Even if hydraulic fracturing makes easier the extraction, it is also a factor which has bad impacts on our environment. It is not ecofriendly, and can pollute the air. It might contammine water around us with some chemicals that can be toxic to humans. Hydraulic fracking can also cause very small earthquake.
According to a study in the journal ”Earthquake Science”, more than 150 microearthquakes has been caused by hydraulic fracturing. Many states now require companies. The government is not too much involved in solving this problem, even if some states are making some efforts, and require to companies to review chemicals they are using.
Here is a link to a video about natural gas hydraulic fracturing:
http://www.youtube.com/watch?v=lB3FOJjpy7s
References:
http://www.iehn.org/overview.naturalgashydraulicfracturing.php
http://www.popularmechanics.com/_mobile/science/energy/coal-oil-gas/the-hard-facts-about-fracking
http://www.nytimes.com/2012/07/06/opinion/the-wise-way-to-regulate-hydraulic-fracturing.html