With the development of several CO₂ storage operations in the North Sea, there is a clear need to better characterise the seismic hazard and stress state in the region. Faults and associated fracture sets can act as hydraulic pathways for unintended CO₂ migration, ill-defined stress states can lead to numerous operational difficulties, and induced seismicity will be a clear risk as CO₂ is injected into subsurface reservoirs. Seismicity can reveal the location and extent of faults and fractures, and can be used to invert for the state of stress. Both operators and regulators therefore need a clear understanding of the rate of natural seismicity, to identify and distinguish induced events from natural, and to assess the likelihood of induced fault reactivation. This requires a dedicated, site specific background monitoring programme, as well as a high-quality seismic catalogue for the region around any CO₂ storage operation. Our study has produced the first dedicated seismic catalogue of the North Sea, based on all available data from each of the relevant seismological agencies. This dataset fosters further studies into seismic hazard, leakage risk, and stress state in a region that will be vital for European CO₂ storage efforts in the coming decades.@en

North Sea subsurface structures provide prolific opportunities to reduce Europe’s carbon footprint through permanently storing emitted CO2. In this paper we present a methodology to estimate resilience of manmade facilities and environment to potential induced seismicity during injection operations, based on historically observed regionally seismicity. This enables a robust design of a well informed risk management system that provides confidence to stakeholders while properly recognizing and establishing the right level of resilience to seismic events. The method is demonstrated by applying the assessment for offshore structures on the Norwegian shelf to address resilience to potential seismicity around the NorthernLights prospect. It appears that is likely an event with Moment Magnitude equal to 3.7 can be managed adequately. The method can be extension to other areas in the North Sea, such as the Dutch and UK sectors, and can also address for instance resilience of onshore domestic areas to offshore induced events.@en