Fault Stability

It is known since decades that human activity can potentially trigger or induce earthquakes, resulting from the changes in the stresses acting on the seismogenetic structures. Early known examples of (low-intensity) induced seismicity are related to hydroelectrical dams, medium-deep and deep geothermal plants as well as oil and gas exploitation. More recently, the re-injection of formation fluids and wastewater in tight formations has also raised concerns and debates on how to prevent the risk of seismicity while continuing the exploitation of the natural resources, also in view of the green transition during which geothermal energy will play a major role. Reduction of the seismic risk requires understanding fault behavior, the conditions of fault reactivation, and the conditions leading to the on-set of faulting (creation of new faults). There is also necessity for a detailed real-time monitoring which will help evaluate possible indicators of increased seismic risk, and that will provide an early-warning mechanism.

Fault stability analysis
  • To understand the risk of fault reactivation, numerical modelling should be pursued in order to:


    • Understand the initial state of stress, before human activities, and quantify whether the fault system is critically stressed
    • Evaluate the changes of stresses acting on the fault system, using large scale 3D models (if available) as boundary conditions
    • Calculate a fault stability index (likelihood of reactivation) considering different scenarios.


    Isamgeo uses multiple approaches, depending on the available data and geological complexity. These solutions can range from simplified 1D scenarios, in which just the evolution of the stress path is considered, to detailed 2D and 3D numerical simulations. In more complex models, all stresses that are acting on the system –pore-pressure and temperature changes in particular– are considered together with their re-arrangement, with possible arching effects.