# Influence of Loess-Mudstone Strata Structure on Slope Seismic Stability of Loess Plateau in China
## 1 Introduction  
Loess is a special soil that accounts for approximately 10% of the total coverage area of soil, with a wide global distribution [1]. Due to its unique characteristics, such as aerial pores, weak cementation structure, and collapsibility [2], it is easily destroyed when subjected to strong earthquakes, leading to a large number of loess landslides and resulting in serious casualties and property losses. At the same time, loess areas are often areas with frequent earthquakes; for example, the Loess Plateau, the largest loess distribution area in the world, is an earthquake-prone area. Historically, six violent earthquakes of magnitude M > 8.0 have been recorded here [3], providing a large number of cases for the study of loess seismic landslides. In 2017, loess was identified as a challenging soil by the International Technical Committee on Earthquake Geotechnical Engineering. Therefore, it is imperative to explore the formation rules of loess seismic landslides to reduce the disaster impact. Research interest in loess seismic landslide disasters began with [PERSON] et al. 's [4] field investigation of loess landslides induced by the Haiyuan earthquake. Since then, investigation and statistical analyses have been some of the main methods of studying loess seismic landslides, specifically the topographic conditions, geomorphic characteristics, geological structures, disaster range, and seismic parameters of typical loess landslides in different intensity regions. Various researchers have summarized the classification of the landslides [5, 6], analyzed the basic characteristics of landslide distribution [7], refined the understanding of the ideal geological conditions for the formation of landslides, and determined the maximum sliding distance [8]. These provided basic information for the study of the failure process and risk assessment of landslides induced by earthquakes. In addition, the improvement of satellite remote sensing image resolution and the wide application of unmanned aerial vehicle (UAV) low-altitude photogrammetry have provided great convenience for landslide investigations; compared to field investigations, these methods can quickly analyze the number and distribution of landslides [9]. [PERSON] et al. [10], [PERSON] et al. [11], [PERSON] et al. [12], and [PERSON] [13] carried out significant works on the spatial distribution characteristics and development models of seismic landslides using these technologies. In recent years, the use of geotechnical tests and numerical simulations to study seismic landslides has become an interesting approach [14]. These methods also support field investigations and have been widely used to analyze the liquefaction behavior and dynamic properties of Ioess [15; 16; 17; 18], to study the dynamic response and macroscopic deformation and failure process of Ioess slopes [19; 20; 21; 22; 23; 24; 25], and, thus, revealed the formation mechanism of Ioess seismic landslides. Currently, some good results have been achieved, especially in the study of one particular landslide. For example, using the Hilbert-Huang transform (HHT) to transform nonlinear and nonstationary seismic records into Hilbert spectra, the instantaneous frequency energy of the Ioess layer and mudstone layer of the Buzi landslide were compared in terms of time-frequency-energy, and the landslide failure process was studied from an energy perspective [26]. Based on the discrete element theory, landslide models were established using the particle flow code (PFC), and the dynamic responses and motion characteristics of landslides were studied by simulating the motion and interaction between particles under seismic conditions [27; 28].