SIRENS · Seismic noise interferometry for stress analysis

Seismic noise interferometry for stress analysis

Many key challenges linked to the energy transition and environmental safety involve the subsurface. These include geothermal energy, carbon storage, mining, and the assessment of geological hazards. In all these cases, understanding how rocks are stressed underground is essential, because stress influences how fractures open or close, how faults may reactivate, and how the subsurface responds to natural or human-induced changes. One particularly important parameter is the orientation of the maximum horizontal stress (SHmax). This information is commonly obtained from boreholes or other local measurements, which can be expensive, invasive, and spatially limited. As a result, there is a strong need for alternative methods that are less intrusive and can potentially be applied over broader areas. The SIRENS project explored a passive seismic approach to this problem. The idea behind the project was to investigate whether very small changes in seismic wave velocity, driven by solid Earth tides and measured through ambient seismic noise correlations, could be used to infer stress orientation in the Earth’s crust. Ambient seismic noise is continuously generated by natural and human activity, while solid Earth tides produce small but regular stress variations caused by the gravitational pull of the Moon and the Sun. Together, these signals offer a promising way to probe the mechanical behaviour of the subsurface without active sources or drilling. The project focused on the Iberian Peninsula, a region with diverse tectonic settings, abundant seismic data, and high relevance for georesources and geohazards. Its overall objectives were to refine the methodological framework required for this type of analysis, test its applicability at regional scale, and explore its potential at smaller spatial scales. In the longer term, this research line could contribute to the development of new non-invasive tools for subsurface monitoring. Such approaches are relevant to European priorities linked to sustainable resource use, low-impact monitoring, and a better understanding of geological processes affecting environmental safety and the energy transition.

Data: CORDIS, © European Union