Study finds injecting fluid into sedimentary rock can produce bigger, more distant earthquakes than injecting into the underlying basement rock.
A study of earthquakes induced by injecting fluids deep underground has revealed surprising patterns, suggesting that current recommendations for hydraulic fracturing, wastewater disposal, and geothermal wells may need to be revised.
Researchers at UC Santa Cruz compiled and analyzed data from around the world for earthquakes clearly associated with injection wells. They found that a single injection well can cause earthquakes at distances more than 6 miles (10 kilometers) from the well. They also found that, in general, injecting fluids into sedimentary rock can cause larger, more distant earthquakes than injecting into the underlying basement rock.
"This is problematic, since the current advice is to preferentially inject into the sedimentary sequence as a theoretically safer alternative to the basement rock," said Emily Brodsky, professor of Earth and planetary sciences at UC Santa Cruz.
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