FINSEIS · Quantitative analysis of the structural controls of faults on induced seismicity magnitude

Quantitative analysis of the structural controls of faults on induced seismicity magnitude

Induced seismicity refers to earthquakes related to human activity and can be caused by a range of industrial activities involving underground fluid injection operations such as Enhanced Geothermal System (EGS), Carbon Capture and Storage (CCS), Hydraulic Fracturing (HF) and Waste Water Disposal (WWD). Often, it involves a large number of low-moment magnitude earthquakes (Mw<2), but larger earthquakes (Mw>3) also occur. While the low-magnitude earthquakes typically cause limited societal concerns and risks, the larger ones can have a negative impact on the conduct and development of industrial operations. Specifically, hazards due to large magnitude induced seismicity are critical in the context of EGS and CCS operations, which are strategic activities in Europe designed to help diversify energy sources and minimize carbon emissions. Previous studies aiming at understanding the controls on induced seismicity have been mainly focused on seismological, mechanical and engineering factors. By contrast, our understanding of structural factors, such as fault zone internal geometry, remains limited. In particular, previous forecasting methods typically considered faults as simple planar geometries, disregarding the segmented nature of faults and its potential impact on earthquake magnitude. This project aims to provide a fundamental understanding of fault structural controls on fluid-related seismicity and help integrate realistic fault zone geometry into seismic studies and forecasting methods. During its three-year duration, the project has focussed on the following specific research objectives: (i) Identify the role of fault segmentation on spatio-temporal event migration. (ii) Quantify the structural control on earthquake rupture dynamic. (iii) Formalize an algorithm for risking IS magnitude integrating realistic fault zone geometry. (iv) Verify and test the role of fault geometry on induced seismicity magnitude for a range of field examples. By adopting an alternative structural approach, the project provides an empirical, theoretical and numerical basis of fault structural controls on seismicity beyond state-of-the-art and helps improve algorithms for induced seismicity prediction. The findings are policy-relevant and impact the European economy and society because they inform geo-energy field developments, improve risk assessment and reduce investment risk. The project also produces fundamental scientific outcomes and informs research on the links between fault zone processes and earthquakes.

Data: CORDIS, © European Union