## 4 Results
### SBA Analysis  
According to the SBA, the cross-correlation functions were defined between the time series of rate of the air temperature and the rock temperature, revealing very high correlation values. The time  
Figure 8: Fast Fourier transform, FFT (**a**), and block/wall SSR (**b**) obtained for the 15 Hz and 20 Hz shaking tests. The rock block dynamic amplification response at 20 Hz is visible (**b**). Dashed lines indicate the standard deviation values. Time-frequency analyses and spectral analyses obtained for the 15 Hz (**c**) and 20 Hz (**d**) shaking tests: on the rock block (up) and on the rock wall behind (bottom). Markers on the spectrograms indicate frequencies due to Vibrodyne excitation (A) and to the power unit supply (B). For the 20 Hz excitation, the possible dynamic response of the monitored rock block can be distinguished. Figure 7: Example of the daily strain cycles over 10 days within the rock mass due to cyclic thermal input during the Summer season. series of rate of the air temperature always anticipates the time series of rate of the rock temperatures by approximately 10 min. The cross-correlation function was also carried out to compare the time series of rate of the rock temperature and the time series of rate of the cumulative rainfall and wind speed to verify whether these last two forcing actions can influence the temperature of the rock block, thus changing the deformation response in the heating or cooling phases of daily or seasonal thermal cycles. The results of the statistical analysis show a slight influence of rainfall on the rock temperature, returning very low cross-correlation coefficient. No significant cross-correlation was found between the time series of rate of the wind speed and the time series of rate of the rock temperature (Figure 9). The cross-correlation analyses were performed taking into account the time series of rate acquired over the entire monitoring period, during which several meteorological conditions (i.e., high or low rock temperatures, intense or absent rainfall, and strong wind speeds) were detected, representing potential destabilising actions for the stability of the monitored rock block. In accordance with the SBA, cross-correlations were carried out among the time series of rate of each considered forcing action, which were assumed as _preparatory factors_[12], and the time series of rate of the strain recorded along joints or micro-fractures. The obtained results show that rainfall and wind speed are always poorly or very poorly correlated with the rock mass strain. On the contrary, the rock temperature reveals a very good cross-correlation with the rock mass strain, demonstrating a significant influence on the rock mass deformation. In this case, no significant lag between the thermal action and the induced strain effect was observed, i.e., the high rock temperature can be regarded as the main forcing factor, which can cause a response of the jointed rock mass within a short to very short time. The obtained results confirm that temperature pulsation is the most influencing factor for the strain effects induced in the outcropping rock mass. In this regard, all the strain devices return rate series that are always cross-correlated with the time series of rate of the rock temperature, and the CF value is always high and above the threshold of statistical significance, as it varies in a range from \(-0.3\) in the Winter season, when the thermal input into the rock mass is low, to \(-0.8\) in the Summer season, when the thermal input into the rock mass is higher (Figure 10). Figure 9: (**a**) Correlogram of the cross-correlation between the rock temperature and the air temperature. The air temperature always anticipates the rock temperature. The green arrow indicates the statistical significance of the result. (**b**) Correlogram of the cross-correlation between rainfall and the rock temperature. The rainfall anticipates the rock temperature, but with a very low CF value. The yellow arrow indicates the low statistical significance of the result.