Does Fracking Cause Earthquakes?

Gas Wells Are Not Our Friends (GWANOF) reader, Laurie, sent this link in today:

http://motherjones.com/blue-marble/2012/04/does-fracking-cause-earthquakes

Good question. Recent articles have pointed to the probable answer: Yes. This issue is still under study.  But since we have more natural gas than we know what to do with at the moment, why not stop operations and get the answers BEFORE continuing natural gas drilling while crossing our fingers and hoping for the best?  In my view, we haven't had the greatest of luck with that method, given the number and variety of accidents which occur on a regular basis at well pads, compressor stations, and pipelines.  If public health and a sustainable planet mean anything to us, we must put moratoria on gas drilling operations EVERYWHERE.

See also: http://dearsusquehanna.blogspot.com/2012/04/earthquakes-directly-linked-to-oil-and.html