# Geophysical Coupling Before Three Earthquake Doublets Around the Arabian Plate
## 1 Introduction  
The Saudi Arabian Peninsula corresponds with a tectonic plate with the same name, i.e., the Arabian Plate. The Arabian plate moves globally as a rigid block of rock, as depicted by geodetic studies [1]. Still, more recent and precise research based on several Global Navigation Satellite System (GNSS) stations identified some different motions on a local scale, which can be due to weaker sections of the lithosphere and subsurface magmatic activity [2]. In addition, the whole plate, roughly anti-clockwise, follows a rotation of about half a degree every thousand years [2]. The independent motion of the Arabian Plate began in the late Oligocene and has been reproduced with experiments in the laboratory, which produce different scale tectonic and magmatic processes [3]. The interactions of the Arabian Plate with surrounding plates are complex [4]. They involve an extensional border with the African Plate distributed along the Red Sea and the Gulf of Aden. On the other side, it presents a transcurrent border on the South-East with the Indian Plate, a compressional/transcurrent border on the North and North-East side with the Eurasian plate, and a particular interaction in the North-West with Eurasian and Anatolian plates. At this point, a recent catastrophic earthquake took place on 6 February 2023 at the border between Turkey and Syria [5]. This event was investigated by studying possible signals before its occurrence, such as atmospheric alteration and degassing from active faults,particle precipitations or ionospheric electromagnetic disturbances from Swarm satellites and ionosonde data [6; 7]. A possible interplay with the space weather, geomagnetic activity and the Turkey 2023 earthquake was investigated by [PERSON] and [PERSON] [8]. Due to these complex interactions, the seismicity is concentrated on the borders of the Saudi Arabian Peninsula, especially on the Southern and Eastern sides toward Pakistan and Iran, as visible in Figure 1. On the Western side of the Arabian plate, there is evidence of volcanic fields, but the role of magma plumes in the region (e.g., Afar one) is enigmatic [9]. Some models of the asthenosphere and lithosphere settings below and in the surrounding areas have been provided by [PERSON] et al. [10], and [PERSON] and [PERSON] [11] provided information about the composition and depth of the lithosphere of the Arabian Plate. To search for possible coupling between the lithosphere, atmosphere, and ionosphere, we will focus on the last ten years due to the availability of data from the European Space Agency (ESA) Swarm mission. In this paper, we will focus on three doublet earthquakes that occurred in the last ten years. Table 1 summaries the main parameters of these selected earthquakes, such as epicentre coordinates, hypocentral depth and magnitude. In order to study the preparation phase, we will consider the doublet as a single event with equivalent magnitude, which is provided by the sum of Richter energy \"E\" calculated from the magnitude \"\(M\)\" with the following formula:  
\[\mathrm{E}[J]=10^{(1.5\times M+4.8)} \tag{1}\]  
Figure 1: Historical seismicity of Arabian Plate. The map shows the M6.0+ earthquakes recorded by USGS from 1 January 1900 up to the present time (i.e., 15 August 2024). The investigated earthquakes are marked with red stars. The above equation is suitable for calculating the total energy released by an earthquake from its magnitude, and preferable, this needs to be the moment magnitude Mw [12]. In the cited book, the sum factor of the exponent is 11.8, but it's equivalent to 4.8 used in this work because the energy was provided in ergs. The study of the preparatory phase of the earthquake investigates the possibility of the existence of precursors. This type of study is quite controversial, especially regarding the possibility of predicting a future earthquake [13]. There are anyway two logical steps: one is to identify some pre-earthquake signals, generally at posterior analysis; the second is to use this information in a prospective way.