EOF ANALYSIS APPLICATION IN DETECTING POTENTIAL PRE-EARTHQUAKE ANOMALIES FROM SWARM SATELLITE DATA

The goal was to examine the potential of the Empirical Orthogonal Function (EOF), also known as Principal Component Analysis (PCA), in detecting anomalous earthquake precursory variations in Earth’s ionosphere - lithosphere geomagnetic system. Two major earthquake episodes in China have been selected: M6.0 quake, 86 km ENE of Arzak, on 19.01.2020, and the M6.3 quake, with epicentre in western Xizang, on 22.07.2020. The spatial-temporal variability patterns in an ~800 km radius of earthquake epicentres were calculated using geomagnetic data, collected onboard SWARM A, B and C, ESA’s low earth orbiting (LEO) satellites. Eight significant EOF and PC components were identified on a 3 - month and 1- year time scale.
When observed in earthquake’s seismotectonic setting, anomalous patterns were revealed along and on borders of the local tectonic fault lines and around earthquake epicentres. At the time the anomalous patterns occurred, solar activity was indicative of quiet periods, strongly suggesting the pre-cursory connection between detected geomagnetic anomalies and subsequent earthquake events.