While there is risk of induced seismicity associated with carbon capture and storage underground on a large scale, it is currently a much less serious risk than other injections. Wastewater injection, hydraulic fracturing, and secondary recovery after oil extraction have all contributed significantly more to induced seismic events than carbon capture and storage in the last several years. There have actually not been any major seismic events associated with carbon injection at this point, whereas there have been recorded seismic occurrences caused by the other injection methods. One such example is massively increased induced seismicity in Oklahoma, USA caused by injection of huge volumes of wastewater into the Arbuckle Group sedimentary rock.