Amherstburg Earthquake - Right under a giant salt operation
I just had to look for drilling rigs. This is much better! We can now say the earthquake was due to the operations. Could be the extraction of weight, which is good for a thrust earthquake. Or they are injecting ever deeper.
There was a big Attica NY earthquake due to salt operations. Again, if there are no more earthquakes, then it's a mass-removal thing, which is as close as you can get to 'pure'. More earthquakes indicate injection.