Improving microseismic monitoring
The monitoring of microseismic activity refers to the passive detection of vibrations caused in rocks as a result of human activities, including mining and rock fracturing. The technique calculates locations and magnitudes of rock failures, maps spatio-temporal evolution of rock fracturing and contributes to the assessment of seismic hazard. Funded by the EU, the project 'Advanced industrial microseismic monitoring' (AIM) was intended to stimulate research in the field and to foster inter-agency cooperation via secondments. The project included six European partners and one each from Canada and South Africa, running over four years to September 2013. The research team developed new methods for calculating parameters of rock fracturing. In particular, the novel method models tensile micro-earthquakes, when fractures are open or closed during rupture. Since complex seismic analysis needs high-quality observations, the group installed a seismic mini-array at Dobra Voda, Slovakia to monitor seismic activity near a nuclear power plant. The mini-array enhanced the sensitivity of an existing seismic network maintained by a project partner, yielding a finer resolution. Given the success of the first mini-array, the project added a further three seismic stations in the area. The developed methods were applied by the team members to several other seismically active areas to monitor earthquake swarms in the geothermal area in West Bohemia in the Czech Republic, to assess an unstable rock slope in Norway, and to study mining tremors in Australia, Finland and South Africa. The measurements yielded better understanding of natural tectonic processes and of the stress release caused by mining. Project results were presented at several international conferences and workshops, and yielded 14 peer-reviewed scientific papers in total. Three postdoctoral fellows benefitted from the project's secondment programme. The AIM project helped create teams of researchers now capable of a higher level of work in the field of microseismicity. The field, and European research overall, also benefits from the newly forged cooperative links between academic institutions and industrial partners.