# Three-Dimensional Processing of Reflections for Passive-Source Seismology Based on Geometric Design
## 1 Introduction  
Passive-source seismic exploration, which is based on seismic wave interferometry, was developed by [PERSON] [1] and [PERSON] and [PERSON] [2]. This method is different from active-source seismic exploration in that it does not require excitation by an artificial source or knowledge of the number and locations of the sources. Correlations can be used to convert environmental seismic noise or micro-earthquakes into a determined seismic response. The theory of seismic interferometry involves \"perform[ing] correlations on the seismic records received by receivers at two points on the surface, and the results can be regarded as the records of the wave field of the active source, with one point as the receiver and the other point as the source\" [3, 4]. Applying this calculation to all random signals of the receiver can yield a group of virtual shot records of the passive source that are similar to forward records of the active source in seismic exploration. Methods of passive-source seismic exploration can be divided into techniques for investigating passive-source surface waves [5, 6, 7] and passive-source body waves [8, 9, 10, 3, 11], according to the types of seismic waves. Because the Earth absorbs body waves to a much greater extent than surface waves, it is much more difficult to capture images of the former than the latter [12]. Some researchers have retrieved reflections of waves from ambient noise by using illumination-based diagnosis [13, 14], while others have sought to improve the quality of data on reflections of the passive source [15, 16, 17, 18, 19]. Methods of exploring reflections of the passive source have been applied in many areas. [PERSON] et al. [20] calculated the velocities of the P-wave and the S-wave, thebundle factor of the P-wave, and other structural parameters based on seismic noise in field data obtained from observation wells in Cold Lake, Alberta, Canada. Seismic wave interference technology was used to investigate the presence of metal ores by [PERSON] et al. [21]. [PERSON] et al. [22] applied passive source exploration to the four-dimensional dynamic monitoring of carbon dioxide storage sites at an Aquistore facility. [PERSON] et al. [23] used data on underground activity in a mine and vibrations of the ventilation pipes in the context of exploring mining resources, and [PERSON] et al. [24] used the noise in waves generated by a railway to monitor the shallow crust. [PERSON] et al. [25] also used a receiver array to monitor long-term seismic velocity and anticipate geological events. According to the theory of passive seismic exploration, sources of random noise are needed to evenly identify geological targets from all directions and obtain accurate kinematical results. Artifacts may be obtained when the source is not located along the direction of the receiver line [14]. Three-dimensional (3D) passive-source seismic exploration can be used to obtain more uniform information and images of better quality than two-dimensional (2D) passive seismic exploration. [PERSON] et al. [12] and [PERSON] et al. [26] obtained the underground velocity from environmental noise by using seismic wave interference technology and generated a corresponding 3D seismic profile. [PERSON] et al. [27] used the full-scale 3D seismic method of the virtual source survey to explore the Kylylahti polymetallic mine in Finland and obtained geological information that could not be obtained through active seismic exploration. While 3D passive seismic reflections have delivered promising results, they require intensive computations as well as a large storage space for the data obtained. Given these issues, we propose a method to calculate images of 3D reflections based on the geometric design of the area. We use information on the area, the surface, and the underground structure to design a reasonable geometry for it, subsequently use that to screen for effective data to obtain correlations, and finally generate an imaging profile with uniform folds and azimuths.