# The First Seismic Imaging of the Holy Cross Fault in the Lysogory Region, Poland
## 4 Seismic Data Analysis  
Seismic imaging of near-surface faults employs a variety of methods to precisely image and interpret fault structures. The most precise is reflection seismic imaging, which provides high-resolution images of the subsurface. It is often combined with other techniques to enhance data quality and image resolution [28]. To help with the critical stage of velocity analysis aimed at precisely estimating seismic wave velocities, multiple forms of seismic  
Figure 3: Overview of seismic acquisition setup. (**A**) shows a surface elevation map with the seismic line marked; (**B**) captures the field acquisition setup using the PEG-40 seismic impact source; and (**C**) provides a schematic representation of the two-deployment acquisition layout. tomography are widely used. This technique most often uses the easiest way to identify the first arrivals of seismic waves to create a seismic velocity model of the subsurface, which is used in reflection imaging, and moveout and stacking procedures [29]. To image the weathering layer, which is the most homogenous near-surface feature, a multi-channel analysis of surface waves (MASW) is conducted [30]. This technique describes the velocity of shear waves, which are used to identify velocity heterogeneities across faults and are very sensitive to ground water variations. In areas with very complex subsurface at the shallowest part of a few meters, geo-radar techniques are irreplaceable [31]. It creates high-resolution reflection electromagnetic wave images of the subsurface on a sub-meter scale and is particularly useful in mapping faults in the first 5 m from the surface where seismic methods resolution is limited. In our analysis, we focus on reflection imaging and travel time tomography as those techniques are the most precise and optimal for implementing to described geological targets. In the case of reflection imaging, the accuracy of the final interpretation is directly dependent on the quality of the processed data. It is essential for the interpreter to be fully aware of any issues encountered during both the field data acquisition and processing stages. A data processing geophysicist must possess a comprehensive understanding of the regional geology of the basin and the specific nuances of each processing step. There is no standard procedure for processing; each geological context presents unique challenges [14]. Seismic data processing plays a critical role in enhancing seismic reflection signals, minimizing noise, and ensuring the precise spatial localization of seismic events. This process comprises three primary stages: pre-processing, pre-stack analysis, and post-stack analysis. The fundamental steps in processing land seismic data consist of static corrections, deconvolution, migration, and stacking [32]. The workflow itself was carefully optimized, with extensive testing and the optimal parameters for each step in the processing workflow selected, to improve the imaging of near-surface data, which was notably affected by residual and near-surface zone variations. Key steps within the applied processing workflow involve pre-processing analysis, noise attenuation, static corrections, and velocity analysis. The first stage in the seismic processing workflow is pre-processing, which serves as the foundational preparation phase. This stage includes sorting seismic data into an appropriate format, vertically stacking multiple shots recorded at the same location, updating geometry and trace headers, removing bad traces, and addressing phase reversals [33]. Following this, static corrections are applied to compensate for variations in velocity and thickness within the weathered layer and to account for elevation changes at the surface. Here, the fixed datum is set at 380 m, and the replacement velocity is 750 m/s. Refraction statics are used to address long-wavelength static issues related to elevation variations, while residual statics correct short-wavelength variations from changes in the weathered layer.