Earthquakes with a local magnitude lower than 2.5 are called microearthquakes and are rarely felt.
Human activities in hydrocarbon reservoirs, mining areas, large water reservoirs or geothermal sites induce microseismicity.
Those activities involve changes in stress, pore pressure, volume and load, which can result in sudden shear failures in the subsurface usually along pre-existing weakness zones such as fault structures.
Long-term microseismic monitoring in hydrocarbon reservoirs has the potential to reveal fracture geometry and to investigate the process of fluid fronts during production.
With respect to safety and hazard issues, long-term monitoring can be valuable in evaluating processes especially for the geothermal. Microseismic monitoring provides valuable input for safety and hazard assessment.
Explorations for hydrocarbon and geothermal purposes.
Monitoring of microseismicity or acoustic emissions defines fault networks and help investigate strains associated with production, water flooding or stimulation.