The preparation phase of earthquakes is poorly known due to the lack of data at hypocentral depth, dense monitoring systems on the surface, and physical constraints. Despite this, statistically, there are several pieces of evidence that atmospheric and ionospheric disturbances may precede some earthquakes. These findings come from joint studies of magnetic and plasma data from the European Space Agency (ESA) Swarm constellation and overall China Seismo Electromagnetic Satellite (CSES-01). So, the present question is not if the Lithosphere Atmosphere Ionosphere (LAIC) coupling exists but the mechanisms of interaction and coupling among the geophysical layers. There are several models suggesting a pure electromagnetic coupling (EM waves from the cracks in the lithosphere), more complex models based on the accumulation of electrical charges (like p-hole) and physical-chemical processes or Acoustic Gravity waves (AGW). Some models also invoke the release of fluids from seismogenetic faults before strong (M6+) or major (M7.5+) earthquakes.
Multiple studies show that the lithosphere, atmosphere and ionosphere coupling can also occur before volcanic eruptions, and the mechanisms could be compared with that of earthquakes even though the source is different (magma upraising for volcanoes). These types of precursor were analyzed, among all with Ultra Low Frequency (ULF) geomagnetic and electric field data (Hayakawa et al., 1994). The ground observations of EM waves in the ULF range (f < 10 Hz) are considered the most promising tool for the monitoring of the crustal dynamics because the skin depth of EM is comparable to the depth at which crustal activities take place, and fluctuations of electric conductivity in the Earth’s interior can be detected directly) Molchanov et al., 1992; Hattori et al., 2004). The most common ULF waves used as pre-earthquake ULF anomalies in the geomagnetic field is Pc3 (Yomoto 2009)
This international team aims to identify the mechanisms of the lithosphere atmosphere and ionosphere coupling. In particular, we aim to investigate which are the mechanisms of coupling as a function of the geographical context (land or sea), the rupture style from focal mechanisms (reverse, strike-slip or normal faults), depth and magnitude of the incoming event. Furthermore, in this proposal, the earthquake source will be approximated by a rupture surface. Preliminary investigations show that considering the segment that the seismic event has broken, the atmospheric pre-earthquake investigations can be better interpreted by discriminating anomalies not related to the incoming earthquake from the ones possibly related to it. We expect to constrain better the characteristics of the anomalies in the lithosphere, atmosphere, and ionosphere more likely related to pre-earthquake and pre-eruption phenomena in the light of the physical-chemical relationships of a specific LAIC model and atmospheric chemistry as well as ionospheric plasma physics.