What is the Frack to Earthquake Ratio?

A lot of people have become frightened by a possible link between oil & gas drilling and fracking, and small earthquakes. It might be helpful to determine what the ratio between fracking and quaking has been, over the years;

Stefan Baisch, one of the authors of the Cuadrilla report, is also general manager of the German deep-drilling research firm Q-Con. He has a PhD in seismology and has spent 10 years researching induced seismicity. Baisch points out some hard facts about fracking that confirms Cuadrilla’s ‘worst-case scenario’ assessment. Referring to Cuadrilla’s operation, Basich states, “There have been more than a million similar treatments in the world over the last 50 years or so, and there are only two cases where similar seismic reactions occurred.” _EnergyTribune

According to that particular German expert, the odds from 50 years of experience with similar treatments are roughly 500,000 : 1, or lower. The risk of falling down at home and dying is higher than that. Here's more:

... in September 2011, a report by the economic development agency Regeneris Consulting on the economic impact of shale gas for the UK underscored just what shale gas development would mean in the UK. The Regeneris report states that Cuadrilla’s operations alone could create up to 5,600 highly-paid skilled jobs in the UK, with 1,700 of those based in Lancashire, a region of high unemployment. Other parts of Britain are thought to be sitting on large reserves of shale gas, too. Regeneris states that experience from the United States shows that shale gas development would have a significant downward pressure on domestic wholesale gas prices. In short, the shale gas revolution offers the social holy trinity of real jobs, regional regeneration and national economic revival.

Micro-quakes and acts of urban terrorism may make the headlines, but the real substance of the global shale gas phenomenon is its potentially enormous socio-economic impact. To borrow scale from Richter: while environmental concerns are at a magnitude of 1 to 2, the socio-economic benefits threaten a seismic 8 to 10. _EnergyTribune

Most persons are willing to accept a vanishingly small risk of tiny earthquakes in exchange for "real jobs, regional regeneration, and national economic revival." How about you?