Seismicity variations in space and time in the area of the Saamy fault, Khibiny Massif, Kola Peninsula

Abstract

The paper analyzes the dynamics of seismicity in the vicinity of the Saamy fault, Khibiny Massif, Kola Peninsula. The qualitative recording of seismic events has been carried out there since 2008. The study area is characterized as rockburst-hazardous and complicated by a geological fault, is developed by open pit mining, and includes the Kukisvumchorr and Yukspor deposits. In order to identify the influencing factors and mechanisms of rock mass failure, the authors used the spatial–temporal clustering of data, and analyzed the location and possible causes of the clusters. The areas with long-term seismic activity near the fault and the areas with short-term increase in seismic activity which is often induced by triggering factors are detected. The clusters in the console part of the rock mass are identified. At the Yukspor deposit, rock mass failed and caved into the Saamy open pit. It is found that opencast mining with blasting in the fault zone is a trigger for the fault activation, which is confirmed by seismic events recorded not only at the working level but also higher. The seasonal increase in water inflows is an additional factor in the fault activation; some clusters are characterized by a higher level of seismic activity during such periods. According to the authors’ conclusion, the analysis of seismicity on the basis of spatial and temporal data clustering allows timely revealing of seismic activation causes and enables necessary preventive measures (rock mass destressing, sectional breaking, bulk blasting to reduce stress level, etc.), which in general reduce the risks of man-induced catastrophes.