Mining Tremors

(induced seismicity)

This term characterizes the dynamic phenomena which is similar in its nature to earthquakes. However, they are locally-like and are related to mineral deposits exploitation. Disturbed geomechanics equilibrium by mining operation produces this type of phenomenon, hence the often used term - induced seismicity. Mining activity induces mechanical stress occurring in the rock mass. The effect of high pressure in the rock mass are mining tremors. As a result of vibration caused by the mining tremors may be local destruction of mine workings, or facilities located in the zone of influence of the tremor. Mining tremors generate elastic waves on the surface of the terrain. These waves can cause deformation (displacement), vibration, and usually have an adverse effect on the nervous system of the inhabitants. Induced mining tremors waves may also lead to damage to buildings and infrastructure in the area of the epicenter.

Vibrations generated by the tremors are recorded by seismic devices, accelerometers and other specialized equipment. The object of the measurements is to determine the location of the hypocenter, epicenter and the parameters of the mining tremor. These parameters are: the intensity (magnitude, seismic energy, wave velocity, vibration acceleration), frequency, extent, duration.

In the case of mining tremors typical energies of vibration does not exceed 1x109J, oscillation frequency ranged from 1 to 30 Hz, duration does not exceed 1-8 sec. Also the range of harmful influences not normally exceed 1,000 m, although recorders detect vibrations from a distance of hundreds of kilometers.