In the past several years, some energy technologies that inject or extract fluid from the Earth, such as oil and gas development and geothermal energy development, have been found or suspected to cause seismic events, drawing heightened public attention. Although only a very small fraction of injection and extraction activities among the hundreds of thousands of energy development sites in the United States have induced seismicity at levels noticeable to the public, understanding the potential for inducing felt seismic events and for limiting their occurrence and impacts is desirable for state and federal agencies, industry, and the public at large. To better understand, limit, and respond to induced seismic events, work is needed to build robust prediction models, to assess potential hazards, and to help relevant agencies coordinate to address them.The report concludes that "Of all the energy-related injection and extraction activities conducted in the United States, only a very small fraction have induced seismicity at levels noticeable to the public (that is, above magnitude 2.0)." [Right, sites with earthquakes caused by or likely caused by various energy technologies. Figure 1 from the report. None are reported in Arizona.]
One of the most significant conclusions is "Hydraulic fracturing to date has been confirmed as the cause for small, felt seismic events at one location in the world. The process of hydraulic fracturing a well as presently implemented for shale gas recovery does not pose a high risk for inducing felt seismic events."
In contrast, the report notes, "Tens of thousands of waste water disposal wells have been drilled in the United States to dispose of the water generated by geothermal and oil and gas production operations, including shale gas production. Water injection for disposal has been suspected or determined a likely cause for induced seismicity at approximately 8 sites in the past several decades."