Human-Induced Earthquakes: Scientists Shed Light on Complex Physical Mechanisms, Industrial Activities That Could Increase Seismic Activity

While it is known that humans have drastic impacts on the world and on their natural environment, little is known regarding how humans have the capacity to induce earthquakes.

Human-Induced Earthquakes

Certain industrial activities, including fracking for oil and natural gas as well as geothermal energy production, have the capacity to heighten seismic activity in the common form of earthquakes. There are extreme cases where the earthquakes could result in casualties and consequent impacts.

Geophysicists from Freie Universität Berlin along with colleagues from ETH Zurich, the University of Pisa, Stanford University, and the Southern University of Science and Technology were able to summarize the complicated physical mechanisms that could lead to earthquakes induced by humans. Their results were noted in the "The physical mechanisms of induced earthquakes" and "Production-induced seismicity indicates a low risk of strong earthquakes in the Groningen gas field" studies. Findings could aid with minimizing the negative side effects that result from technological innovations, such as carbon or geothermal energy storage practices. The findings could be relevant for industry representatives, Earth scientists, policymakers, and regulatory authorities.

The researchers investigated that human-induced earthquakes can take place during certain industrial activities, including conventional hydrocarbon recovery, enhanced geothermal system development, fracking of unconventional resources, mining operations, underground gas or carbon dioxide storage operations, wastewater disposal, and reservoir impoundment. They found that earthquakes were induced by fluid extraction or injection underground that primarily took place along critically stressed faults that were pre-existing.

Triggering Earthquakes

According to Serge Shapiro from Freie Universität Berlin, poroelasticity and pore-pressure diffusion were found to be the major triggers of extraction-induced and injection-induced seismicity. Liquids that get injected deep within the earth reduce the typical stress that acts over fault planes and fractures. This may destabilize the faults and lead to earthquakes.

A crucial finding of their efforts is that trigger mechanisms for earthquakes that are human-induced could differ depending on the location. One aspect that has a crucial role in this is the complicated interaction between various industrial activities, especially in areas where huge volumes of wastewater contaminated with hydrocarbons get exposed and where fracking occurs.

There were also other factors, such as the volume of gas or liquid injected, the distance between the wells of injection or extraction, and the distinct hydrological and geological characteristics of an area, that were seen to be relevant when it comes to complex physical mechanisms that could stress rock formations that surround them.

The researchers recommend the setting up of a microseismic monitoring network at every site of industrial operations in order to offer an early warning system for earthquakes that are induced.

Geophysicist Cornelius Langenbruch explains that, at present, human-induced seismicity risks can only be statistically estimated. Models of forecasting typically consist of just a handful of physical factors. Due to this, the study stresses the significance of physics-based models that can get the multiphysical processes linked to the seismicity that is induced. These models may also consider the propagation and initiation of fault ruptures at various scales.

Mohammad Javad Afshari Moein, a geophysicist and the study's lead author, explains that by developing forecasting models based on physics and reducing human-induced earthquake risk, they could enhance the social acceptance of geothermal technologies that are next-generation.

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