"It is unlikely that all of Oklahoma's recent earthquake clusters can be attributed to human activities, state geologist G. Randy Keller says in a position statement released Monday." Dr. Keller said linking earthquakes to human activity "requires careful examination of a large amount of complex data and does not happen quickly."
Yes, Oklahoma has a state geologist who is also a petroleum geologist. And, he has chosen his words carefully. The USGS has just released a report that it is likely that the increased incidence of earthquakes is caused by man's activities.