The development, testing and implementation of a method for managing earthquakes triggered by human activities is reported in Nature this week. The method was shown to manage triggered seismicity associated with the injection of waste water in the seismically active Val d’Agri oil field, Italy.
Concern over seismicity (frequency, intensity and distribution of earthquakes) induced by human activities — such as mining, water extraction or the injection of water into subsurface reservoirs — has been growing in recent years. However, there is a lack of understanding as to how such earthquakes can be best managed.
Bradford Hager and colleagues created a model using detailed subsurface information about the Val d’Agri oil field, the largest onshore oil field in western Europe, situated in an area of ongoing tectonic activity. They calibrated their model with records of hydrocarbon extraction and water injection rates and associated fluid pressure changes from January 1993 to December 2016. This information was combined with geomechanical models and earthquake physics models to predict the evolution of fluid pressure and stress, and the resulting changes in the likelihood of earthquakes. The authors used this model to forecast expected seismicity between January 2017 and December 2025 across three different water injection rates. It was calculated that a relatively low injection rate was sustainable and should not induce seismicity. They trialled the method from January 2017 to June 2019 and found that seismic activity was consistent with the levels predicted by the model.
The authors suggest that this approach can be employed in other areas and could improve our understanding of managing earthquakes associated with human activity.
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