## 2 Materials and Methods
### Earthquake Catalogue  
The earthquake catalogue was acquired from the INGV ISIDE [4] earthquake web portal ([[http://cnt.rm.ingv.it/](http://cnt.rm.ingv.it/)]([http://cnt.rm.ingv.it/](http://cnt.rm.ingv.it/)), accessed on 2 January 2023) by the selection of the events inside the square box delimited by 34.4\({}^{\circ}\)N \(\leq\) latitude \(\leq\) 44.5\({}^{\circ}\)N and 9.8\({}^{\circ}\)E \(\leq\) longitude \(\leq\) 15.9\({}^{\circ}\)E from 1 st January 2018 until 1 st January 2023. No constraints were selected for magnitude and depth. The geographical positions of all the events are shown in Figure 1a. The seismicity induced by the very long Italian Seismic Sequence of Amatrice-Norcia-Capitigliano (Montereale) 2016-2017 [5] is visible in the diagonal from the northwest to the southeast sides of the map of Figure 1a. The completeness magnitude \"Mc\" was analysed by the ZMap software [6], excluding the events associated with the Amatrice-Norcia-Capitigliano Italian Seismic sequence (i.e., the event more than 50 km from the Guidonia 2023 earthquake) to avoid a bias in the analysis. In fact, the Apennines central region of Italy, affected by this sequence, was more thoroughly covered with permanent seismic stations and temporary stations after the start of the same sequence. The completeness magnitude was estimated to be Mc = 1.4, as visible in the graph in Figure 1c. In addition, this graph represents the Gutenberg-Richter law [7] with \"a\" and \"b\" values, which represent the amount of recorded seismicity and the ratio between smaller and higher magnitude events in the region, respectively. The \"a\" value is the decimal logarithm of the amount of M0+ earthquakes in the investigated area in the analysed time, or during one year. The b-value is generally found to be equal to 1 at a global or regional scale. Before large earthquakes, its value can decrease, indicating  
Figure 1: Earthquakes that occurred in Central Italy from 1 st January 2018 until 1 st January 2023. (**a**) Geographical map of the earthquake (EQ) events with active seismic fault from DISS: the yellow star represents the event of Guidonia 1 January 2023, ML = 3.3; the red circle is its Dobrovolsky area; grey circles are the tested Dobrovolsky areas; the green dashed rectangle is the area used to calculate atmospheric time series, and the black dashed circle is the research area for ionospheric investigations. The adapted colour bar scale shows the hypocentral depth. (**b**) Enlargement of the map around the Guidonia (Rome) earthquake. In addition to previous details, the principal local towns are shown in relation to recorded seismicity. The transcurrent fault proposed by [PERSON] [1] is reported with a dashed-dot green line. (**c**) The Gutenberg–Richter (G–R) distribution of the magnitude of the earthquakes, excluding the seismicity in the northeast corner of the map, i.e., within a radius of 50 km from Guidonia epicentres. The magnitude of completeness and G–R parameters are reported. a lack of larger-magnitude events in the statistic [8; 9]. Only earthquakes with magnitude M \(\geq\) Mc will be considered in the following analyses. The cumulative Benioff stress was computed for the events inside the Dobrovolsky radius. Benioff stress is an indication of the stress accumulating on a fault [10]. The Dobrovolsky radius is a distance typically used to estimate the preparation area of an earthquake [11]. In particular, Dobrovolsky's radius in kilometres is  
\[r_{Dob}=10^{(0.43\cdot M)}\]  
The Benioff cumulative stress _S(t)_ could be empirically estimated by the following formula:  
\[S(t)=\sum_{i=1}^{N(t)}\sqrt{10^{(1.5\cdot M_{i}+4.8)}},\]  
where \"\(i\)\" is the \(i\)-th earthquake with magnitude \(M_{i}\), and \(N(t)\) is the total number of earthquakes that occurred until the time \(t\). According to [PERSON] et al. [12] and [PERSON] et al.