Case Studies of Depletion Induced Seismicity Using Rate & State Modeling for Probabilistic Discrimination and Hazard
T. Dahm, S. Cesca and S. Hainzl
Event name: 77th EAGE Conference and Exhibition - Workshops
Session: WS07 - Production Induced Seismicity
Publication date: 01 June 2015
Info: Extended abstract, PDF ( 973.44Kb )
Price: € 20
Earthquakes with magnitudes M>4 have occasionally been observed close to depleted reservoirs after longer periods of production. Events of this size can be felt and pose a significant hazard for population and infrastructure. Key questions are whether such events can be associated as depletion induced, how reliable they can be discriminated against natural but rare tectonic events, and whether we can assess their seismic hazard. We suggest a probabilistic approach based on the relative rates of natural and induced seismicity. We employ a rate and state seismicity model combined with modelled rates of Coulomb stress. The quantitative model is able to forecast the relative increase of earthquake probability during depletion as a function of space and time. We use this estimate to define a trigger potential function for the earthquake. In addition, the human induced question can be considered if a fault smoothing filter is applied to the trigger potential function. The method is applied to different earthquakes in Europe, showing that some of the significant earthquakes were human-induced, human-triggered or caused by natural tectonic stresses. We discuss possible extensions to earthquakes occurring during the re-filling of depleted reservoirs for gas storage facilities and the assessment of time dependent hazard.