## 1 Introduction  
On 18 April 2021, at 6:41 UTC (11:11 Iran Standard Time), a M\({}_{\rm W}\) 5.8 earthquake occurred near the city of Bandar-e Genaveh, in the seismically active area of the Bushehr province, southwestern Iran (Figure 1). This earthquake occurred in the strongly active area, with structures oriented mostly northwest-southeast and dominated by right-slip and reverse fault mechanisms [1, 2]. It did not cause casualties, extensive damage or surface ruptures in the affected area [3]. There were 200 aftershocks following this earthquake over the next 4 months, with 20 of a magnitude higher than 4 [4]. Among them, a large aftershock of M\({}_{\rm W}\) 5.0 occurred on May 21, potentially causing additional surface displacements. A number of studies have investigated this earthquake using finite fault modeling (Table 1) based on different techniques. However, there are inconsistencies between the different fault models. According to the Harvard group and the U.S. Geological Survey (USGS), the Global Centroid Moment Tensor (GCMT) solution is a fault-plane solution that is consistent with nearly thrust-slip motion, but the USGS solution prefers a smaller seismic moment release. In order to reconstruct the complex active fault system of the investigated area, we exploit the InSAR (Interferometry from Synthetic Aperture Radar) two-pass technique, a well-consolidated instrument to retrieve the surface deformations [5]. InSAR is, indeed, a geodetic technique capable of obtaining high resolution displacement maps with centimetric accuracy over a wide area [6]. These maps reveal the displacement in LoS (Line-of-Sight)  
In this study, we infer the source of the 2021, M\({}_{\rm W}\) 5.8, Genaveh earthquake through the modeling of ascending and descending InSAR displacement data, providing the fault geometries, kinematics and the slip distribution for the mainshock. We also investigate how the convergent tectonics of this region relate to the obtained causative fault. We additionally investigate the possibility that the M\({}_{\rm W}\) 5.0 aftershock induced some co-seismic surface effects by calculating and modeling two more InSAR displacement maps. The outcome of this analysis, however, did not provide an evident conclusion. Geological and Tectonic SettingThis area is located in southwestern Iran, within the complex Neogene collision zone between the Arabian and Eurasian plates, with a tectonic shortening rate of approximately 6.5 \(\pm\) 2 mm/yr [14] as a result of post-collisional crustal shortening that is transferred to the foreland structures and ophiolite abduction [18; 19] (Figure 1). This area is one of the most seismically active intra-continental fold-and-thrust belts on Earth. Zagros Mountains and their coupled foreland basin were evolved during a multi-episodic orogen from the Late Cretaceous to recent times [20]. The estimated \(\sigma_{1}\) axis in Zagros Folded and thrust Belt (ZFTB) trend rotates in anti-clockwise direction from NE-oriented trajectories to the southeast to \(\sim\)N-oriented trends to the north [10]. There are four major active faults in ZFTB, which are the Zagros Foredeep Fault (ZFF), the High Zagros Fault (HZF), the Mountain Front Fault (MFF) and the Main Zagros Reverse Fault (MZRF). Most of these faults trend NW-SE and NNW-SSE, with dips of 30-60\({}^{\circ}\) and rakes of 60-120\({}^{\circ}\) along the plate boundary [9; 21]. There is an older sequence of deformation in the inner parts of Zagros chain and a younger sequence in the outer Simply Folded Belt since the Late Cretaceous to Pliocene period [17]. In this region, several tectonic units are divisible from northeast to southwest with non-uniform deformation [10].