A natural gas extraction method known as fracking is under sharp scrutiny in several states.
Natural gas is a clean source of energy, but fracking comes with many environmental drawbacks.
Fracking may cause small earthquakes in regions that are seismically quiet, but one earthquake does not help scientists make a conclusion either way.
Explains the pros and cons of fracking, particularly regarding the use of water as fracking fluid.
Explores the increase in earthquakes in Oklahoma and the hypothesis that they are caused by the injection of fracking fluids into the ground.