# Geophysical Coupling Before Three Earthquake Doublets Around the Arabian Plate
## 3 Results
### Atmosphere  
The climatological data of MERRA-2 was used to investigate the atmosphere, searching for anomalies six months before our three case studies were compared with the multi-year typical values. Surface air temperature, aerosol, SO\({}_{2}\), CO, and Dymetthil Sulfide (only for  
Figure 2: Cumulative Benioff Strain calculated the three case studies of earthquakes from USGS inside [PERSON]’s area that occurred six months before the doublet. The blue dashed vertical line represents the first earthquake of each doublet case, and it’s excluded from the red curve. sea earthquakes) have been observed. Figure 3 reports the sulphur dioxide time series in the six months before Dehloran (Iran), 2014 earthquake doublet. When the value in the year of the earthquakes (red dashed line) overpassed the yellow bands (i.e., the two standard deviations of historical values), we can classify the specific days as anomalous and further discuss them if eventually related to the incoming seismic event and several anomalous days concentrated from 100 to 80 days before the main events. There are also other spot anomalies, one of which is worth noticing, that occurred just one day before the Dehloran (Iran) events. In addition, the air surface temperature map of the 7 May 2014 has been shown in Figure 4. This was an anomalous day that preceded 103 days the Dehloran (Iran) earthquake doublet. At the same time, SO\({}_{2}\) anomalies were also recorded, as visible from the previous graph in Figure 3. The temperature map is very interesting because the distribution is well-aligned with the plate border. Furthermore, the anomaly that is between 6 K and 8 K more than the typical value is significant, with a level between 2\(\sigma\) and 3\(\sigma\) of the standard variation of the surface air temperature in the 30 years before in the same region (see Figure 4 right). For the case of Kilmia, Yemen, 2018, we show the aerosol trend in the six months before the event in Figure 5. We selected this parameter because it shows more anomalies in the last 1.5 months before the case study. Several parameters show anomalies around 25 May 2018. Checking the weather, it seems that the anomalies were caused by a peak of rain in the region that probably induced a release of heat from the ground and other anomalies, but it is worth excluding that they may be linked to the incoming seismic events. The excluded years could be caused by other natural hazard events. For example, in 1991, the eruption of the Pinatubo volcano in Indonesia emitted an amount of SO\({}_{2}\) and aerosol for more than one month in all the regions of the world in the equatorial belt, as shown by [PERSON] et al. (2014). Figure 3: Time series of sulphur dioxide six months before Dehloran (Iran), 2014 earthquake doublet. The blue line represents the typical trend of SO\({}_{2}\) calculated on the other years (2014 is excluded) from 1980 to 2023. Its standard deviation is represented by light blue, green, and yellow bands that stand for 1.0, 1.5, and 2.0 times the standard deviation. The red dashed line is instead the SO\({}_{2}\) value observed in the year of the earthquake doublet, i.e., 2014. Figure 6 presents the time series of SO\({}_{2}\) before the Bandar-e Lengeh (Iran) 2022 earthquake doublet. It's outstanding to underline that the highest and anomalous value of SO\({}_{2}\) was recorded on day 171 of the time series, which corresponded to 21 June 2022, well inside the seismic acceleration that preceded the double events that started a few days before. The SO\({}_{2}\) could be the product of a degassing caused by the ongoing seismic activity that preceded the main shock. Figure 4: Map of Surface Air Temperature on 7 May 2014, an anomalous day from the corresponding time series.