# Development of Multi-Channel Seismic-Electrical Combined Rolling Coverage Measurement System
## 1 Introduction  
Today's society is in an era of rapid technological development, and human demand for resources has reached unprecedented heights [1]. The security of supply for strategic energy sources, such as oil and gas, is crucial [2]. To meet the increasing demand for resources like these, it is of great importance to continuously improve traditional geophysical instruments [3]. Electrical and seismic exploration are two widely used geophysical methods in geological surveys [4]. Electrical exploration technology is a geophysical method used to detect geological structures, locate minerals, and find water based on the differences in resistivity and polarization characteristics of soil and rock [5]. It has many advantages, such as a high resolution and accurate results. Common electrical exploration methods include the natural potential method, resistivity method, induced polarization method, and controlled-source audio-frequency magnetotellurics (CSAMT) method [6]. The resistivity method is used to detect underground anomalies based on the differences in resistivity of subsurface materials [7]. As shown in Figure 1, the instrument supplies power to theearth through electrodes \(AB\), creating a stable electric field underground, while measuring the supply current \(I\). The instrument measures the potential difference \(\Delta U\) between two points on the surface using electrodes \(MN\), and calculates the apparent resistivity value (\(\rho_{s}\), in units of \(\Omega\cdot m\)) at the midpoint between electrodes \(M\) and \(N\) using the formula \(\rho_{s}=K\cdot\Delta U/I\). Seismic exploration infers the structure and properties of underground rock layers by analyzing how artificially generated seismic waves travel through media with varying elasticity and density [8]. The elastic waves generated by artificial excitation produce reflected and refracted waves when they encounter the boundaries between rock layers. These waves are recorded by highly sensitive instruments as they return to the surface. By analyzing the travel distance and travel time of the waves, the burial depth and shape of the rock layer interfaces where the elastic waves are reflected or refracted can be determined, thus allowing the inference of underground geological structures [9]. Traditional electrical exploration measures current and potential sequentially via a single channel, leading to low efficiency. Currently, high-density electrical instruments are mainly designed for engineering surveys. Although they offer a greater number of measurement channels (typically dozens or more), their output power is relatively low (usually only a few kilowatts), resulting in limited depth penetration. As such, they are not suitable for mineral or other resource exploration at depths of several hundred meters. Additionally, high-density electrical instruments typically do not support rolling coverage measurements. For long survey lines, the instrument must be repositioned multiple times, leading to increased operational workload and reduced efficiency. Once measurements at the current electrode positions are completed, the entire electrode and cable system must be repositioned to continue the survey, making the process time-consuming and labor-intensive. Furthermore, traditional geophysical exploration systems typically employ a single method, which limits their effectiveness in complex geological environments. Under such conditions, strong scattering and shielding effects can significantly weaken subsurface signal illumination [10]. Seismic and electrical exploration data can complement each other, leading to more reliable imaging of underground structures. Therefore, fully utilizing the advantages of multiple exploration methods for combined exploration has become a current research highlight [11; 12; 13]. Seismic and electrical data contain complementary information, and their joint inversion can effectively improve the imaging resolution of underground geological structures and the accuracy of reservoir descriptions [14].