## 1 Introduction
[45] developed a monitoring and regulating system of the interference of the wave shape in order to reduce vibrations according to the millisecond delay timing. The optimum time of delay could be deduced from different times of delay and the propagation of surface waves to simulate times with different boreholes taking into consideration various conditions of timing; by applying this method, the interference of the wave shape can be achieved, leading to a reduction in the vibration. [PERSON] and [PERSON] [46] investigated the influence of the maximum explosion capacity on the delay and the choice of the optimum interval for the reduction in the vibration intensity by the interference of the wave shape. According to the terrain experiments, the maximum charge capacity for the delay was 15 ms, which enabled the vibration to be reduced by 24.5%. The paper describes the results of research that was realized in Trebejov Quarry and its surroundings. The aim of our research was to identify the values at which the seismic impact of the blasting operations does not damage the buildings in the environment of the quarries and the inhabitants of the buildings are not subjected to vibrations by the blasting operations, which could be dangerous for them. Through the Slovak Hygienic Standards, the impacts of the vibrations on inhabitants are determined by the measurement acceleration of the vibration in the buildings and other places where the inhabitants are living. However, the most accurate standard cannot prevent inhabitants living in the housing nearby the quarries from complaining about the impact of the blasting operations, as they perceive them negatively; nevertheless, they do not measure them accurately. The problem with the inhabitants of the housing is that they accentuate only the negative impact of the blasting operations/complaints of the inhabitants, causing the quarries and mining facilities existing near to the expanding housing agglomerates higher financial and time costs. By applying the modified millisecond timing and monitoring the blasting operations in the quarries, we tried to experimentally record the optimum interval of particle velocity values and their frequency which would not affect the inhabitants in a negative way. Within this research, a series of six research blasts was performed in Trebejov Quarry, whereas the seismic impact of these blasts on the housing was measured in the village of Trebejov. There were two measuring points at our disposal for measuring the impact of the blasting works. The purpose of these blasts was to carry out research, and they were designed in order not to exceed the limits in accordance with legal provisions. During the first research blast No. 693, the charge was blasted only in one borehole without any propagation delay. In the case of further research blasts, two boreholes were blasted with an increased propagation delay of 1, 5, 10, 15 and 20 ms. In all cases of these research blasts, the seismic impacts of the blasts on the given measuring points were measured and evaluated. The results of this research were also compared with those of the vibrographs of the common surface mining blasts.