SSC Selection Post 2025 PYQ — Question 14

Correct Answer

A substantial increase in earthquakes triggered by injection and production

Explanation

Over the past decade, seismologists and geologists have documented a substantial increase in earthquakes linked to human activities involving subsurface fluids. The high-volume injection of wastewater into deep disposal wells, primarily associated with oil and gas production processes like hydraulic fracturing, increases pore pressure along pre-existing faults. This fluid pressure counters the frictional forces holding the faults together, causing them to slip and trigger induced seismicity or man-made earthquakes.

Key Points

Human activities such as deep-well wastewater injection and geothermal energy production alter the stress state of the Earth's crust by introducing high-pressure fluids.

The dramatic rise in seismicity has been particularly notable in regions with extensive oil and gas development, where earthquakes were historically rare.

Managing these subsurface fluid operations requires careful monitoring of fluid volumes, injection rates, and local geological fault structures to mitigate the risks of induced earthquakes.

Important Questions and Answers

Question: What is the main cause of induced earthquakes related to oil and gas production?

Answer: The main cause is the high-pressure injection of wastewater into deep disposal wells, which increases fluid pressure along underground faults.

Question: How do subsurface fluids trigger a fault to slip?

Answer: The subsurface fluids increase the pore pressure within the fault zone, which reduces the effective friction keeping the fault stable and allows it to slip.