Home Health Best practices for environmental health : environmental pollution, protection, quality and sustainability
Seismic Activity Caused by Humans (Induced Seismicity)
(See endnotes 69, 70)
Fracking or horizontal drilling and a high volume hydraulic fracturing not only has helped produce more oil and natural gas but also has created a substantial problem of how to dispose of the wastewater including injected fluids deep into the ground. There is a concern that the high volume fracking process and the injection of these large amounts of wastewater and other fluids are causing or increasing seismic activity. Some of the earthquakes have been at a magnitude of 4.0-4.8 and have caused damage to structures on the surface of the ground. Recent research indicates that the majority of wells used for hydraulic fracturing cause micro-earthquakes. Contributing to this seismicity are three factors: a buildup of enough pressure from disposal activities to cause the problem to occur; a fault of concern which is set to create problems in a critically stressed area; and a means for the pressure to move from the injection area to the fault area. Pressure can be transmitted for many miles through fractures. It appears that in certain instances the magnitude of the earthquakes increases with increased exposure to the disposal of wastewater. Unfortunately, many of these areas have natural fractures.
Since the 1920s, it has been known that pumping of any kind of fluids in or out of the earth, as well as the filling of a reservoir, can cause seismic activity. Although there is a need for considerably more research concerning the amount and rate of waste fluid injected into the deep wells as well as other operational aspects, there is a potential for creating fractures in the rock formations and increasing seismic activity.
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