How can fluid injection and extraction contribute to induced seismicity and what policies mitigate this risk?

• A. They alter pore pressure and stresses on faults; licensing, monitoring, and reducing injection rates, plus transparency and risk-based closure
• B. They have no effect on seismicity
• C. They strengthen faults and reduce earthquakes
• D. They only affect volcanic activity

Answer: (C)

Fluid injection and extraction change the underground pressure and the stress balance on faults, which can allow slips that wouldn’t happen otherwise. Injecting fluids raises pore pressure in rocks, this lowers the effective normal stress that holds a fault in place, making it easier for tectonic stresses to cause the fault to slip and produce an earthquake. Pulling fluids out can also alter the stress field and rock mechanics, redistributing stresses in ways that can trigger seismic events. Because the likelihood and size of induced earthquakes depend on how much and how quickly pressure is added or removed, careful management matters.

Policies that mitigate this risk focus on controlling and understanding how the fluids move and how the subsurface responds. Licensing ensures oil and gas or geothermal projects are planned with known faults and risk in mind. Monitoring—especially seismic monitoring near injection sites—helps detect increasing activity early. Reducing injection rates or slowing the ramp-up if seismicity increases limits pressure changes. Transparency and risk-based closure mean sharing data with regulators and communities, and having clear plans to throttle back or shut down operations if seismic risk becomes too high.

Choices that say there is no effect, that only volcanic activity is involved, or that injections strengthen faults do not fit, because fluid movement clearly changes pore pressure and stress in the crust and that is linked to triggering seismicity, not to the suppression or absence of earthquakes.