How can enhanced geothermal systems trigger earthquakes?

Enhanced geothermal systems (EGS) can trigger earthquakes, a phenomenon known as induced seismicity, through the process of creating or expanding underground fracture systems.12

Unlike traditional geothermal plants that utilize existing steam or water reservoirs, EGS targets hot, dry rock with low permeability. To extract energy, operators drill wells and pump water into the rock at high pressure. This process is similar to fracking used in the oil and gas industry. The high-pressure injection forces open existing fractures or creates new ones to increase the rock's permeability.31

This manipulation of subsurface stress can destabilize the rock, leading to seismic activity. While many induced events are minor, EGS projects have been linked to more significant earthquakes, such as the magnitude-5.5 event in Pohang, South Korea, in 2017, which caused injuries and extensive property damage. Because these activities pose clear risks to public safety and infrastructure, it is ethically imperative that developers prioritize rigorous seismic monitoring and safety protocols to protect local communities.12