# Detection of Electromagnetic Seismic Precursors from Swarm Data by Enhanced Martingale Analytics
## 4 Quantitative Experiment
This approach allows us to zoom in on areas with higher seismic risk, potentially increasing the sensitivity of our anomaly detection algorithm to relevant electromagnetic field fluctuations preceding seismic events. Additionally, the aggregation of data points to form daily mean averages helps smooth out noise and fluctuations, providing a clearer signal for anomaly detection. This preprocessing step is essential for ensuring the robustness and reliability of our analysis, particularly when dealing with high-frequency data generated by Swarm satellites. By incorporating both temporal and spatial dimensions into our analysis, we can better understand the relationship between electromagnetic field activity and seismic events. This multidimensional approach enables us to uncover potential patterns and correlations that may have previously gone unnoticed, ultimately contributing to our understanding of seismic precursors and improving our ability to forecast and mitigate earthquake risks. Our case studies focus on the earthquakes that occurred in Mexico (19 September 2017--[[https://earthquake.usgs.gov/earthquakes/eventpage/us2000](https://earthquake.usgs.gov/earthquakes/eventpage/us2000) ar20/executive]([https://earthquake.usgs.gov/earthquakes/eventpage/us2000](https://earthquake.usgs.gov/earthquakes/eventpage/us2000) ar20/executive) (accessed on 10 March 2021)), Greece (30 October 2020--[[https://earthquake.usgs.gov/earthquakes/eventpage/us/000c7y0/executive](https://earthquake.usgs.gov/earthquakes/eventpage/us/000c7y0/executive)]([https://earthquake.usgs.gov/earthquakes/eventpage/us/000c7y0/executive](https://earthquake.usgs.gov/earthquakes/eventpage/us/000c7y0/executive)) (accessed on 10 March 2021)), and Croatia (29 December 2020--[[https://earthquake.usgs.gov/earthquakes/eventpage/us6000d3](https://earthquake.usgs.gov/earthquakes/eventpage/us6000d3) zh/executive]([https://earthquake.usgs.gov/earthquakes/eventpage/us6000d3](https://earthquake.usgs.gov/earthquakes/eventpage/us6000d3) zh/executive) (accessed on 10 March 2021)). The earthquake in Mexico occurred on 19 September 2017, with its epicenter--latitude 18.550\({}^{\circ}\) N and longitude 98.489\({}^{\circ}\) W--located near the town of Raboso in the state of Puebla, approximately 120 km southeast of Mexico City. The earthquake, with a depth of 48 km, had a magnitude of 7.1 and caused widespread devastation, resulting in hundreds of fatalities and significant damage to buildings and infrastructure in Mexico City and the surrounding areas. The earthquake in Greece struck on 30 October 2020, with its epicenter--latitude 37.897\({}^{\circ}\) N and longitude 26.784\({}^{\circ}\) E--situated near the island of Samos in the eastern Aegean Sea. The earthquake, with a depth of 21 km, had a magnitude of 7.0 and was felt across a wide area, including parts of Greece and Turkey. It caused buildings to collapse, resulting in casualties and injuries, particularly in the city of Izmir, Turkey, and on the island of Samos. The earthquake in Croatia occurred on 29 December 2020, with its epicenter--latitude 45.424\({}^{\circ}\) N and longitude 16.257\({}^{\circ}\) E--located near the town of Petrinja in central Croatia. The earthquake, with a depth of 10 km, had a magnitude of 6.4 and caused significant damage to buildings and infrastructure in Petrinja and surrounding areas. It resulted in several fatalities and numerous injuries, as well as widespread displacement of residents. We present the outcomes of the case studies in a methodical, chronological order, meticulously sorted by ascending grid size. Each geospatial boundary grid underwent a thorough analysis, yielding three distinctive plots showcasing the original EMF data. Theseplots include (1) the unaltered raw data, providing a baseline perspective; (2) the data augmented with anomalies identified by the Martingale framework overlaid, highlighting potential disruptions or irregularities; and (3) the anomalies identified by our innovative framework overlaid, offering further insights into nuanced variations.