# The Conditional Probability of Correlating East Pacific Earthquakes with NOAA Electron Bursts
## 4 Discussion
\(\mathrm{V_{T}}\) and \(\mathrm{V_{A}}\) cover the entire East Pacific area, while \(\mathrm{V_{P}}\) is restricted to two latitudinal areas being more extended on the west. In red is the possible precursor volume which hypothesizes a physical action on the ionosphere of the future epicenter lithosphere. The V\({}_{\rm T}\) can be obtained by multiplying the East Pacific area by the total number of hours [27], this total number corresponds to N\({}_{\rm h}\) = 36,135 for 4 h intervals. The following was observed in V\({}_{\rm T}\): a total number of N\({}_{\rm EQ}\) = 199 EQs with M \(\geq\) 6 and depths \(\leq\) 200 km, resulting in a P(EQ) = 0.0055, a total number of N\({}_{\rm EB}\) = 3371 EBs which are alarms, and a total number of N\({}_{\rm S}\) = 37 CEs which are successes. The success rate was calculated by N\({}_{\rm S}\)/N\({}_{\rm EB}\) = 0.011, which is the conditional probability (1) [27], 1 \(-\) (N\({}_{\rm S}\)/N\({}_{\rm EB}\)) = 0.989 is the false alarm rate, while the alarm rate is N\({}_{\rm S}\)/N\({}_{\rm EQ}\) = 0.186, and the failure rate is 1 \(-\) (N\({}_{\rm S}\)/N\({}_{\rm EQ}\)) = 0.814. As there were more alarms than those for the West Pacific EQs, with the success being near the same for the two cases, the number of false alarms in this study increased compared to previous research. A cross-correlation of 0.024 was calculated using the relation (3). The EQ occurrence probability of at least one target event was estimated to be P(EQ) when no EB was observed two and a half days before, while it increased to P(EQ | EB) given by (2) two and a half days after the EB observation. The probability distribution is shown in Figure 9, which indicates a probability gain near G = 2. As for the study in the West Pacific [27], days with more than one burst can be found with a frequency of about 20%, and EBs belonging to successive orbits generated a partial overlapping between two consecutive alarms. These are not considered here and will be presented in a future publication. An early warning system for evacuation should be based on effective EQ observations [37]. However, the geohazard risk reduction can gain valuable preparation time by adopting a probabilistic short-term warning a few hours prior, especially for tsunamis [36]. Thus, using NOAA-15 electron CR analysis is in principle achievable based on the infrastructure of antennas operating along the West Coast of the US [28], at the same longitude where EBs are detected. The system would need to be able to download NOAA data early enough so it can be analyzed in a few minutes and then compared with geomagnetic activity within a day. As EBs were detected in the same region where they anticipated West Pacific EQs [27], the probability of a strong EQ in the West Pacific cannot be neglected, which would vanish in less than 4 h. Then, if no strong EQs occur in the West Pacific, based on completely statistical evaluations of disastrous events presented in this work, an East Pacific coast forecasting can be generated using G increases in EQ-probability. Moreover, correlation bins of time lengths greater than 6 h were investigated, they concerned the cases of 7, 8, 9,10, 12, 14, and 17 h. A decrease in significance was generally observed for the corresponding correlations, where the sigma decreased up to 1.1 for the 17 h case. Figure 9: The conditional probability distribution P(EQ | EB) which corresponds to the correlation bin of 4 h in Figure 2, the average probability indicated by a horizontal dashed line coincides with the unconditional probability P(EQ). Furthermore, the probability gain was calculated for each bin and reported in the plot of Figure 10 for each starting/ending time of the correlation peak. The case of 1.5 h was also added to this plot. A fit of the G distribution is reported in Figure 10, which can be interpreted as the time-dependent conditional probability of a strong EQ in the East Pacific area after an EB has been observed at time 0.