# Evolution of the Seismic Forecast System Implemented for the Vrancea Area (Romania)
## 3 Data Collection and Calculation Results, a Case Study
Mean Day = SUM (Channel Weight\({}_{0}\)\(\times\) events\({}_{0}\)/maxim events,...  
Channel Weight\({}_{n-1}\)\(\times\) events\({}_{n-1}\)/maxim events)/n stations  
The maxim of 'Mean Day' is 1 when in all stations 'events' ='maxim events'  
Mean m Daysn = SUM (Mean Dayn-m: Mean Dayn)/m  
\"m\" is the window of days that captures detections. The maxim of 'Mean m Daysn' is 1 when in all stations 'Mean Day' = 1. Seismic energy is calculated with the Richter and Bath formula [18; 19; 20]:  
\[\text{EnergyE}=10^{(11.8+1.5\times\text{M})} \tag{3}\]  
Figure 3: Detecting events with the STA/LTA method was applied to the integrated time series of radon and CO\({}_{2}\) (Figure 2) before the 5.4 local magnitude earthquake, compared with the OEF AFROS signal resulting from the decision matrix. The coefficients 11.8 and 1.5 are empirical and depend on the type of magnitude and location. Their values do not affect the method used. The measurement unit of seismic energy is Erg (ergi), 1 Erg = \(10^{-7}\) Joule. Figure 4: The result of the decision matrix based on level detections. Columns in Table 1: Mean 4 Days (OEF AFROS), Mag R (loacal magnitude, ML), EnergyE, and EnergyE 4 Days. Figure 5: Data flow in updating the decision matrix. Also, Figure 4 shows that 'EnergyE' is more intuitive than its mean over four days. So, in detail (Figure 5):  
- The columns represent the Date/Time, BISRAERd, DLMdd, LOPRdd, NEHRdd, PANCdd are radon, and BISRCO\({}_{2}\), DLMCO\({}_{2}\), LOPrCO\({}_{2}\) represent CO\({}_{2}\);  
- Every day the number of Events for every station is recorded;  
- MeanDay for 22 August 2024: 2 Evens for BISRAERd, and 10 for LOPrCO2, relation (1) (0.125 \(\times\) 2/4 + 0.125 \(\times\) 0/4 + 0.125 \(\times\) 0/4 + 0.125 \(\times\) 10/4 + 0.125 \(\times\) 10/4 + 0.125 \(\times\) 10/4 + 0.125 \(\times\) 10/4 + 0.125 \(\times\) 10/4 + 0.125 \(\times\) 10/4)/8 = 0.046875;  
- MEAN 4 DAYS = (0.0078125 + 0.0078125 + 0.01171875 + 0.046875)/4 = 0.018554688;  
- EnergyE (relation 3) = POWER((1.5 \(\times\) 2.5 + 11.8),10)/10\({}^{+18}\) = 8.26616 \(\times\) 10\({}^{-07}\);  
- EnergyE 4 Days = (0 + 6.80297 \(\times\) 10\({}^{-07}\) + 3.38486 \(\times\) 10\({}^{-07}\) + 8.26616 \(\times\) 10\({}^{-07}\))/4 = 4.6135 \(\times\) 10\({}^{-07}\);  
Figure 5 shows the data flow: data acquisition, event detection in stations, event file transmission, daily counting, weighted daily average calculation (MeanDay), and four-day average calculation (Mean 4 Day). Verification is done by calculating the cumulative seismic energy daily (EnergyE). So, starting from the seismic Events file sent from monitoring stations, the probability of having a seismic event is evaluated. This is the simplest method to implement in our case because we made the data acquisition software and we can implement the detection algorithm. An Event file example for radon in Bisoca station:  
BISRAerd-Events_240911_091400.log -> 24/09/11 09:14:00 ROI1 5.920 < 9.995  
where BISRAerd-Events_240911_091400.log is the name of the file, date (year/month/day) 24/09/11, and time (HH:MM-SS) 09:14:00  
New equipment for monitoring radon and thoron with high precision was installed in Plotstina and Vrancioaia, RTM 1688. The evolution of radon in Plotstina did not show significant variations before the earthquake with 5.4 local magnitude that occurred on 16 September 2024, unlike radon in Vrancioaia, which indicated high values, especially after the earthquake. Meanwhile, thoron in Plotstina did not indicate a seismic event, but that in Vrancioaia exceeded the trigger threshold and several red dots appeared in the STA/LTA graph (Figure 6). The differences in the number of detections (Table 1, Figure 6) can be attributed to the distance from the epicenter (Table 3). The epicentral area should not be considered a direct source of radon for the other monitoring stations; rather, tectonic stress causes soil deformations that influence gas emissions.