How to discriminate induced , triggered and natural seismicity
Human operations, such as mining, hydrocarbon production, fluid withdrawal or injection, drilling, hydro-fracturing and reservoir impoundments, can positively and negatively impact tectonic stresses, pore pressure, fluid migration and strain in the sub-surface. Earthquakes occurring in spatial and temporal proximity to such operations are immediately under suspicion to be triggered or induced. The discrimination between natural, triggered, and induced earthquakes is a difficult task, and clear rules and scientific methods are not well established or commonly accepted. The current practice to distinguish possible causes of earthquakes is not quantitative and individual cases are treated unequally, which often leads to questions on general liability. This situation has a negative drawback for private and public claimants and for companies performing the operations. Moreover, estimations of earthquake-related risk is still difficult.