The experiments were conducted for the study of slick-slip at the cont
act between two granite blocks. Three cases were studied under the fol
lowing conditions: 1) the increase of load at a constant rate; 2) the
additional application of sinusoidal oscillations in the frequency ran
ge from 1 to 30 Hz; 3) subjection to the impulse in the kilohertz freq
uency range. The imposition of sinusoidal oscillations with the amplit
ude of 15% of the maximal load caused the reduction of time by 10% for
the next stick-slip occurrence, as compared to that expected during t
he gradual loading. This effect is discussed in terms of durability. T
he high frequency impulse influence increased this effect and also cau
sed essential changes in the amplitude of elastic oscillations generat
ing during the stick-slip. The trigger phenomena should be integrated
in prediction models of the time and magnitude of earthquakes.