## Results
### Seismological Investigation  
The cumulative Benioff stress was calculated inside the Dobrovolsky area, testing several mainshocks from magnitude 3.3 to 5.5, as listed in Table 1. The lower limit corresponds to the assumption that the 1 January 2023 event is the mainshock. The higher-magnitude events correspond to the hypothesis that a stronger event is incoming. In addition, Table 1 provides the b-value of the Gutenberg-Richter distribution, calculated in the real or tested Dobrovolsky area by ZMap software [6], using the maximum curvature method for more stable solutions. The detailed graphs are reported in Supplementary Materials Figure S1. As previously mentioned, a low b-value could indicate a lack of higher-magnitude events. This low b-value was found in Dobrovolsky's area of tested events with a magnitude between 3.7 and 4.1. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Estimated** & **Dobrovolsky** & **b-Value (In** & **C 1** \\
**Magnitude** & **Radius [km]** & **Previous 6** & **(In the Previous** \\
**Months)** & **6 Months)** \\ \hline
**Real earthquake** & **3.3** & **26.2** & **1.0 \(\pm\) 0.3** & **0.318** \\ \hline  & 3.5 & 32.0 & 1.0 \(\pm\) 0.3 & 0.359 \\ \cline{2-5}  & 3.7 & 39.0 & 0.7 \(\pm\) 0.1 & 0.342 \\ \cline{2-5}  & 3.9 & 47.5 & 0.7 \(\pm\) 0.1 & 0.326 \\ \cline{2-5}  & 4.1 & 57.9 & 0.7 \(\pm\) 0.1 & 0.356 \\ \cline{2-5}  & 4.3 & 70.6 & 1.0 \(\pm\) 0.2 & 0.714 \\ \cline{2-5}  & 4.5 & 86.1 & 1.04 \(\pm\) 0.05 & 0.943 \\ \cline{2-5}  & 4.7 & 105.0 & 1.15 \(\pm\) 0.03 & 1.075 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: List of the real (in bold) and tested earthquake magnitudes with the corresponding Dobrovolsky’s radius. All the events are centred at the epicentre of the ML3.3 Guidonia 1 January 2023 earthquake (41.982\({}^{\circ}\)N, 12.750\({}^{\circ}\)E). The b-value of the Gutenberg–Richter distribution is computed during the six months before the Guidonia earthquake by the maximum curvature method, and details and graphs are provided in Supplementary Materials Figure S1. For each fit, the adjusted statistic coefficient of determination \"adj-R2\" and the estimated time of failure are reported in Figures S2 and S3 (in Supplementary Materials), and in Figure 2 for 5 years, 1 year, and 6 months before the ML = 3.3 Guidonia 1 January 2023 earthquake, respectively. In addition, the acceleration coefficient \(C\) defined by [PERSON] et al. [13] has been reported in Figures S2 and S3 and Figure 2, and Table 1, calculated as:  
\[C=\frac{rms_{power\ law}}{rms_{linear\ fit}},\]  
where \"\(rms_{power\ law}\)\" and \"\(rms_{linear\ fit}\)\" are the root mean square errors of samples \"\(S_{i}\)\" (\(i=1\dots\) N) with respect to their fits \"\(f\)\"; in particular, rms is estimated as:  
\[rms=\sqrt{\frac{\sum_{i}\left(S_{i}-f_{i}\right)^{2}}{N}}.\]  
For lower values of C, the fit represents more acceleration. On the other hand, C = 1 indicates that the trend is linear, and C > 1 indicates that a linear fit is better than the power law. Such a situation could be due to a trend influenced by the aftershocks of another seismic sequence, such as the one of Amatrice-Norcia-Capitigliano (Montereale) Central Italy 2016-2017, in particular for a long trend and a larger radius of analysis. The investigations for 5 years and 1 year before ML = 3.3 Guidonia 1 st January 2023 earthquake do not provide interesting results (Supplementary Materials Figures S2 and S3). In fact, the trends are dominated by another important seismicity which occurred in the area (the Mw = 3.3 11 April 2022, Ciciliano, Rome event, [[http://cnt.rm.ingv.it/event/30543871](http://cnt.rm.ingv.it/event/30543871)]([http://cnt.rm.ingv.it/event/30543871](http://cnt.rm.ingv.it/event/30543871)), accessed on 2 January 2023). The Apennine residual sequence instead dominates the tests, with a larger magnitude cited above. This is the reason why a magnitudes higher than 4.7  
Figure 2: Benioff cumulative stress curves (in red) calculated within six months of the ML = 3.3 1 January 2023 Guidonia earthquake.