Interrelation of subsoil hydrogen emanation during bulk blasting and higher seismicity of the Khibiny massif

摘要

Currently ore mining in the mines of “Apatit” JSC is provided by intense underground andrnopen-pit mining works thus brings about its deepening and results in stress level and seismic activityrnincrease. The Khibiny apatite mines are characteristic of all types of rock pressure dynamicrnoccurrences: external prone-to-rockburst features to rockbursts and mining-induced earthquakes.rnBlock structures, high horizontal stresses, solid brittle rocks, dynamic occurrences of the rockrnpressure in the deep rock mass allow to refer developed mines as prone-to-rockburst or hazardousrnones. Stress-strained state of the rock mass is influenced by antropogenic and natural factors. As arnresult, a sudden block movement along the faults from one another or a new faulting inside the blocksrnor barrier opening between existing fractures take place; it results in seismic events of different energyrnlevels.rnThe important factor having impact on geodynamic situation in the region is the long-termrnantropogenic influence on the rock mass. As a result of ore mining and tailing dumps andrnimpoundments generation, the surface relief has changed significantly as well as type of loads on thernrockmass, tectonic elements relations were found destroyed thus leading to block system instabilityrnand seismic activity increase in the area of mining works.rnIndicators of geodynamic events can be gas components existing in any geological formations.rnGases, due its mobility, are very sensitive to changes in the host rock state. The prospects ofrnmolecular hydrogen emanation as precursors of natural and mining-induced processes were assessed.rnThis paper presents the study results of the interrelation of seismicity in the area of the UnitedrnKirovsky Mine and subsoil hydrogen emanation after blasting works in the mine. Obtained resultsrnproved the assumption that deep hydrogen emanation peaks following the bulk blasting coincide withrnthe further higher seismicity zone formation thus indicating the mining-induced character of thernKhibiny rock mass seismicity.rnInvestigations allowed to find seasonal character of intense gas emanation in time: during summerrnseason vibration frequency of H_2 concentrations significantly increases, independently of explosivernamount. This frequency can be connected with irregularity of the Earth’s rotation about its axes andrnaction of lunisolar tides. Intensity and instability increase of gas emanation is registered during newrnmoon and, in particular, full moon periods and often during the first and the last quarters of the moon.rnAt present time the studies are continued.