## 1 Introduction
Additionally, other mechanisms for electric (or electromagnetic) disturbances have been proposed based on the change of the resistivity of rocks caused by the movements of fluids (the highly conductive water that fills the new cracks) in the crust before the occurrence of the earthquake under the so-called \"Dilatancy Model\" by [PERSON] et al. [17]. For instance, the movement of fluids in Central Italy prior to the occurrence of significant earthquakes has been detected from seismological analyses [18]. Changes in resistivity have been supposed and calculated to describe the atmospheric electric and magnetic field anomalies detected by a ground antenna [19]. Furthermore, ground and atmospheric observations, together with _Swarm_ magnetic field satellite anomalous data, have been proposed as good candidates to describe a pre-earthquake chain of anomalies [20]. A comprehensive review of several models of the Lithosphere-Atmosphere-Ionosphere (or, in some cases, just the Lithosphere-Ionosphere) Coupling models has been provided by [PERSON] et al. [21], where other possible physical couplings are also proposed such as pre-earthquake acoustic gravity waves, atmospheric electric currents possibly generated by the release of charged aerosol, variations in the D and E layers in the ionosphere induced by radon release, a direct resonator between the lithosphere and the ionosphere that is supposed to form a spherical capacitor in this model, and even more challenging possible explanations. Previous statistical works have provided pieces of evidence of the correlation of the ionospheric disturbances in terms of electron density measured by the DEMETER satellite, finding a significant increase from 10 to 6 days prior to the seismic M4.8+ events [22; 23; 24], and an increase in the electric field (typically around 10/20 mV/m) from a few minutes to some days prior to several M5+ earthquakes was reported by [PERSON] [25] using DEMETER and INTERCOSMOS-BULGARIA-1300 satellites. Previous studies by some of the authors of this paper analyzed the _Swarm_ and China Seismo Electromagnetic Satellite (CSES) data prior to the occurrence of about 20 earthquakes in recent years with a magnitude \"M\" in the range 6.0 \(\leq\) M \(\leq\) 8.3 [26; 27; 28]. The worldwide systematic association of detected ionospheric disturbances in the magnetic field and electron density with earthquakes has been statistically proved by [PERSON] et al. [29], and a preliminary investigation of CSES-01 electron density data has also shown promising results [30]. The present work is the natural extension of the first statistical and systematic analysis of correlation using satellite magnetic field data from _Swarm_ satellites with global M5.5+ shallow earthquakes [29]. Here, a temporal extension of the analysis is provided in terms of analyzed time (i.e., 8 years instead of 4.7 years) and the preparation time before the earthquake (from 1000 days before, instead of 500 days before). Furthermore, some new methodologies are also provided to corroborate the results. In Section 2, we provide a brief introduction about the investigated dataset and the data analysis method. Section 3 illustrates the results, which are deeply discussed in Section 4. In Section 5, we present some conclusions and future perspectives.