# The Conditional Probability of Correlating East Pacific Earthquakes with NOAA Electron Bursts
## 3 Results
For what concerns electron pitch angles, they were concentrated in intervals around 67\({}^{\circ}\) and 117\({}^{\circ}\), with 56\({}^{\circ}\)\(\leq\)\(\alpha\)\(\leq\) 72\({}^{\circ}\) and 108\({}^{\circ}\)\(\leq\)\(\alpha\)\(\leq\) 126\({}^{\circ}\). The correlations in Figure 2 were obtained for EQ depths lower than 200 km, supporting the hypothesis that only EQs close to the surface seem to be correlated to ionospheric activity. Figure 2: Correlations were obtained by filling histograms of the time difference \(\mathrm{T_{EQ}-T_{EB}}\) which is positive when EBs anticipated EQs. They are plotted for different bins of 2, 2.5, 3, 4, 5, and 6 h from top left to right; the centers of correlation peaks are 57.2, 56.05, 55.8, 56.3, 57.3, and 57.2 h, respectively; averages are evidenced by the black horizontal dotted lines, while the red ones indicated the 3 \(\sigma\) levels; note that border bins are not completely populated as they are partially out the range of \(\pm\)3 days. The significance of the correlation peaks was calculated for all the cases shown in Figure 2. The plot shown in Figure 4 summarizes the results regarding the number of standard deviations that define the correlation peak significance above the average values concerning the bin duration and the relative average correlated events. A statistical increase in the correlation peak significances was observed, which started to exceed 3 standard deviations for a bin correlation less than or equal to 6 h and reached a maximum of over 4 for a bin correlation of 4 h. The correlation peak significance was less than 3 for bins greater than 6 h. Concerning the number of correlated events, it decreases for short correlation bins. In Figure 4, a continuous red line indicates the number of standard deviations of 57 h correlation peaks observed with different bins, a continuous black line indicates the number of events at the peaks, whereas the dashed line indicates the averages. All the correlation peak significances overcame the threshold of 99%. As in the past publications, both correlation calculus using a randomized space and time distributions of EQs were also calculated by using the same EQ times, and the same EQ epicenters, respectively. In these randomized cases, the previously obtained correlation peaks completely disappeared. Figure 4: The correlation significance in red is compared with the correlation peaks in black and the corresponding correlation averages for the bin intervals reported in Figure 2.  
Figure 3: The L-shell parameter distribution is compared to the EB latitudes; the distribution pattern is different from those of the EB correlation with West Pacific EQs as in this case EB longitudes correspond to the SAA. The maximum number of 45 correlation events was found for the greatest time bin of 6 h, which corresponded to 45 EQs identified in the map in Figure 5. The geographical region where EQs correlated with NOAA-15 EBs is delimited by \(-40^{\circ}\) to \(30^{\circ}\) in latitude and by \(245^{\circ}\) to \(300^{\circ}\) in longitude, the yellow line in Figure 5, so included are regions with strong seismic activity, such as Mexico, Caribbean Sea, Guatem, Honduras, Nicaragua, Costa Rica, Panama, Columbia, Ecuador, Peru, Bolivia, Chile, and a large part of South-eastern Pacific. EQ epicenters are indicated by red dots in Figure 5, about half of which are located offshore. Note that the total number of mainshocks that occurred during 16.5 years in Figure 5 yellow square was 199, they were about 1/3 of the mainshocks that stroked West Pacific in the same period. However, the 45 East Pacific mainshocks of the peak correlation are near the 44 EQs of the West Pacific correlation peak, being the East Pacific correlation bin 3 times the West Pacific correlation bin. The time distribution of the 45 considered EQs from July 1998 to December 2014 is shown in Figure 6, with their relative magnitudes.