Potential earthquake precursory pattern of large Alpine- Himalayan earthquakes as seen by magnetic Swarm satellites

 Before the occurrence of an earthquake and when the lithosphere is in a state of critical stress accumulation, the lithosphere could react- with the so-called earthquake precursors. One of these precursors is the magnetic field, which, under proper conditions, may produce anomalies due to accumulated stress in the crust before an earthquake occurs. Since several years ago, it has been possible to observe the Earth's magnetic field through satellites. The Swarm satellite mission of the European Space Agency was launched at the end of 2013. It is composed of three identical specialized satellites for observing the Earth's magnetic field. Here, using the magnetic measurements provided by Swarm satellites, we investigate the possibility of identifying several anomalous magnetic signals before the occurrence of earthquakes, which are possibly related to lithosphere-atmosphere-ionosphere coupling. In this study, the earthquakes with a magnitude greater than 5.0 occurred from 2014 to 2023 in the Alpine-Himalayan belt under geomagnetically quiet conditions were examined. Using the algorithm applied to the data from 10 days before the earthquake, obvious anomalies in the components of the magnetic field are identified. Furthermore, a significant relationship between the length (duration) of the anomaly and the magnitude of the earthquake was observed and the empirical relationship between them was estimated. For instance, with the enhancement in the magnitude of the earthquake, the duration of the anomaly also increases.

In addition, significant relationships are also found between other parameters and the magnitude of the earthquake with an acceptable correlation.

We also performed a confutation analysis synthetizing a random catalogue of earthquakes and made again the correlation with the satellite anomalies: the results were far different from those obtained with real data, so confirming the validity of those results.