# Geophysical Coupling Before Three Earthquake Doublets Around the Arabian Plate
## 4 Discussion  
This paper extracted anomalies from the lithosphere, atmosphere, and ionosphere during the six months before three earthquake doublets that involved the Arabian plate  
Figure 9: Residual of Swarm Bravo magnetic data acquired on 18 May 2022 at 21:07 UT. The green circle represents [PERSON]’s area of the Bandar-e Lengeh, Iran, 2022 earthquake doublet. The red vertical line is the projection of the satellite orbit on the map. The mean epicentre is shown as a green asterisk. The red dashed ellipse marks the anomaly potentially associated with the earthquake. from 2014 to 2022. Figure 10 summarises all of these results. It reports the cumulative Benioff strain for lithosphere analysis and the physical and chemical anomalies from the climatological dataset MERRA-2 for the atmosphere and Swarm magnetic anomalies for the ionosphere. Only the parameters that show one or more anomalies are visualised. Notably, for the Dehloran (2014) Iran earthquake doublet, the seismic trend from \(-140\) to \(-88\) days is very similar to the atmospheric anomalies from \(-140\) to \(-68\) days, suggesting a coupling between the geo-layers. Looking better at the ionospheric trend, it's possible to see a sharp increase in anomalies from \(-63\) to \(-41\) days. This is very well compatible with a model of lithosphere atmosphere ionosphere coupling with a slow process that takes several days or even weeks to propagate from one layer to the next. In fact, we can roughly estimate a delay of 10 days to transmit the anomaly from one layer to the upper one. It's worth noting that this time is well compatible with the one necessary for geo-gases to transport from hypocentral depth to the ground, according to [PERSON] and [PERSON] (2014). Considering they could transport radon in the atmosphere, it takes a few days (half-life of 3.8 days) to decay, emitting radiation (alpha and beta radiation) that can ionise the area up to changing the atmospheric and consequently ionospheric electric circuit ([PERSON], 2014; [PERSON], 2014). This process can take some days, and our chain of anomalies can be potentially explained by such theories. The involved atmospheric parameters for the Dehloran (2014) Iran earthquake doublet are the SO\({}_{2}\) and CO after the sharp increase of lithospheres cumulative Benioff strain and later increase of aerosols. It could be explained by the Pulinets and Ouzounov model (2014), which predicts the formation of aerosol particles in the atmosphere. A similar release of SO\({}_{2}\) before a different and stronger earthquake, Mw = 7.7 Jamaica 2020 earthquake (Santos, 2014), was reported. The Kilmia, Yemen 2018 case study is less \"perfect\" than the previous one. However, two interesting possible couplings have been noticed. In fact, the two increases in atmo  
Figure 10: Summary of lithospheric, atmospheric and ionospheric investigations in the six months before the three cases under study. spheric anomaly trends occurred just before the only two times (about \(-160\) and \(-30\) days) the ionosphere showed some anomalies by Swarm satellites. The first possible coupling seems synchronous between the atmosphere and ionosphere, while the second one seems to present a delay of more than ten days. If they are couplings between the geo-layers, then they must be produced by a different mechanism: one fast, such as ULF electromagnetic waves [31; 32] and the second one, a slow chain of processes to propagate the anomaly from the atmosphere to the ionosphere [57; 88], as we noticed for the previous case. A similar long delay time for the large M7.5 Indonesia 2018 earthquake [20] has been reported, and a combination of more coupling mechanisms investigating the preparation of the Mw = 6.7 Lushan (China) 2013 earthquake [49] was identified. Finally, the seismic trend shows a clear acceleration ten days before the Kilmia (Yemen) 2018 earthquake doublet. It was followed by an increase in anomalies in the atmosphere, which the increase in lithospheric stress may have induced.