# The Conditional Probability of Correlating East Pacific Earthquakes with NOAA Electron Bursts
## 1 Introduction  
Low Earth Orbit (LEO) satellites fly at altitudes ranging between 200 and 2000 km, providing a platform of observation extending over hundreds of km, thus being able to monitor large regions struck by strong earthquakes (EQs). Likewise, given that LEO satellites are not stationary, and they circle the Earth many times every day, this platform is capable of monitoring the entire Earth's surface, assuring multiple passages on the same areas in a few days [1]. This type of monitoring uses non-seismic detectors which are mainly electromagnetic, being that the atmosphere is absent at satellite altitudes. Non-seismic phenomena observed on the ground during strong EQs are well recognized as happening before, during, and after a seismic manifestation [2]. These phenomena include fluid migration [3], the Earth's electric currents [4], atmospheric phenomena [5], and electromagnetic perturbations [6]. However, at ground level, they can be influenced by local effects, including land, atmospheric variables, and anthropogenic activities [7]. Thus, they cannot be reliably studied and related to the different phases of EQ preparation [8]. In this regard, LEO satellite observations overcome such difficulties by averaging signals on large areas and thus reducing the influence of local phenomena [9]. Electromagnetic detectors at LEO altitudes are also disturbed by atmospheric phenomena [10] and extraterrestrial perturbations mainly associated with the Sun [11]. Therefore, it has been suggested that remote sensing from the near-earth space of phenomena observed with EQs may be associated with seismic phenomena by statistical approaches [12]. An additional advantage of LEO satellites is that regarding terrestrial observations, they areable to continuously monitor multiple regions to investigate many strong seismic events over a few years for statistical analyses [13]. Statistical correlations between time series of strong earthquakes and time series of remotely collected signals have been recently obtained in several fields of electromagnetic observations [14]. A study lasting 7.5 years concerning Pc1 pulsations reported from a low-latitude station in Parkfield, California, an enhanced occurrence probability of such phenomena about 5-15 days prior to EQs, during the daytime [15]. A statistical correlation was calculated for ULF geomagnetic fluctuations, and this phenomenon anticipated moderate earthquakes by 1-5 days at Japanese ground stations [16]. Seismo-ionospheric effects on long sub-ionospheric paths have been investigated in amplitude variations of signals [17; 18]. In a statistical study concerning VLF/LF wave paths, transmitter signal amplitudes revealed perturbations with a frequency excess of 3-6 days before strong seismic events occurred in 10 years [19]. Concerning the magnetometers onboard LEO satellites, shallow earthquakes with M \(>\) 5.5 have been anticipated by both magnetic field perturbation and electron density signals of \(10^{-0.96+0.51\cdot\text{M}}\) and \(10^{-3.46+0.83\cdot\text{M}}\) days, respectively, using the first 8 years of Swarm data [20]. A significant correlation between VLF wave intensity and strong EQs occurring at 0-4 h was observed in a statistical study using the micro-satellite DEMETER [21; 22], where EQs were preceded by decreasing intensities. Furthermore, the largest occurrence rates of anomalies on TEC data from the global ionosphere map were correlated with strong superficial EQs, they occurred 1-5 days before the EQs [23; 24]. Significant increases in electron density measurements observed on board the DEMETER satellite were correlated with moderate seismic events that occurred 10 to 6 days later [25]. A statistical analysis of NOAA POES data has evidenced Electron Bursts (EBs), which are sudden increases in electron fluxes, in the loss cone 2-3 h before the M \(\geq\) 6 quakes in Indonesia and the Philippines [26].