If you would extend your informations to those small and unimportant areas of the world that do not belong to the USA, you would find the example of Gronngen, in Holland. From the sixties a very large gasdeposit was exploited http://en.wikipedia.org/wiki/Groningen_gas_field. In the seventies and eighties small earthquakes occurred in that province, which was peculiar, because there are almost no earthquakes in Holland. But both frequency and strength kept increasing. http://www.nlog.nl/nl/reserves/reserves/reassessment-of-the-probability-of-higher-magnitude-earthquakes-in-the-groningen-gas-field.pdf
To cut a long story of greed and denial short: gas exploitation is now cut back and some damages will be paid.
But what really bugs me is that nobody seems to be aware of this plain and important example of correlation between eqrthquakes and gas/oil exploitation.