How Fluid Injection Contributes to Earthquakes near Changning Salt Mine

What is it about?

This study looks at how industrial water injection in the Changning salt mine area of Sichuan, China, affects local earthquakes. Using two approaches, we calculated how injection changes underground stresses and compared that with the stress needed to explain the observed earthquake activity. We found that injection mainly influenced seismicity within about 2 km of the wells, where pore pressure and stress increases matched the timing and location of earthquakes. Beyond that range, earthquakes were more strongly affected by tectonic stress and by stress transferred from other earthquakes. Overall, our results show that while fluid injection can trigger nearby small earthquakes, long-term seismic hazard is also shaped by the regional tectonic setting.

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Why is it important?

Understanding how human activities like fluid injection contribute to earthquakes is essential for assessing seismic risk. This research shows that injection-induced stress alone cannot explain all the seismicity in Changning. Instead, tectonic forces and earthquake interactions play a large role, especially for larger and more distant events. By distinguishing the part of seismicity caused by injection from that driven by tectonics, our framework provides a clearer basis for hazard evaluation in industrial regions worldwide. This knowledge can help improve monitoring strategies and inform safer resource development practices.

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