Commenters on unthreaded have been pointing to a story this morning about fracking operations near Liverpool Blackpool being halted because of a possible link to earth tremors.
A brief Googling suggests that this is possible, but the implications are not exactly scary.
Earthquakes induced by human activity have been documented in a few locations in the United States, Japan, and Canada. The cause was injection of fluids into deep wells for waste disposal and secondary recovery of oil, and the filling of large reservoirs for water supplies. Most of these earthquakes were minor. Deep mining can cause small to moderate quakes and nuclear testing has caused small earthquakes in the immediate area surrounding the test site, but other human activities have not been shown to trigger subsequent earthquakes. Earthquakes are part of a global tectonic process that generally occurs well beyond the influence or control of humans. The focus (point of origin) of an earthquake is typically tens to hundreds of miles underground, and the scale and force necessary to produce earthquakes are well beyond our daily lives.