Simple model for injection related anthropic mechanism triggering
distant clusters during the 2019-2020 seismicity crisis in Strasbourg
Abstract
Deep geothermal energy is a sustainable energy source. As any activity
associated to deep well injections, geothermal projects require to
mitigate properly risks of triggered seismicity. Among these, the Geoven
project, north of Strasbourg, with two seismic clusters occurring in its
vicinity in 2019-2020, one adjacent to the site and the other 5 km to
the south. We assess the possible link between these activities and
those seismic events. The methodology combines analyzing the fault
geometry and tectonic stresses, pressure perturbations due to injection,
and slip by using a friction criterium. The fault around the southern
cluster is found particularly vulnerable, and minimal pressure
perturbations induced could have been sufficient to trigger seismic
activity there. By contrast, the zone between the clusters is found much
more stable, so that pressure perturbations, even though larger, is not
enough to trigger seismicity there: this explains a spatial gap between
the two clusters.