# Prediction Equation for Horizontal Ground Motion Peak Values in the Loess Plateau Region
## 1 Introduction  
Destructive seismic events have frequently occurred in the Loess Plateau region of China, causing significant casualties and property damage [1]. The loess, widely distributed across the region, has unique soil dynamics characteristics, leading to notable regional variations in seismic activity and damage distribution. Therefore, studying the ground motion attenuation behavior in this specific soil layer can significantly improve earthquake disaster prevention and mitigation efforts. With the continuous improvement of China's National Strong Motion Observation Network, many strong motion records have been recently accumulated from the Loess Plateau region, providing reliable data for establishing prediction equations for ground motion parameters applicable to this area. Building upon existing research, this study uses the latest strong motion records to develop prediction equations for horizontal ground motion parameters in the Loess Plateau region. The study of ground motion attenuation relationships requires a substantial amount of strong motion records. With advancements in observation technology and the widespread deployment of instruments, the global collection of strong motion records has significantly increased. This progress has provided robust support for research on ground motion attenuation relationships [2]. In the early stages, the lack of sufficient strong motion records in the Loess Plateau region made it impossible to directly establish ground motion parameter prediction equations through statistical methods. Instead, the prediction of peak ground motion in this region relied on the conversion method proposed by [PERSON]. This method established attenuation relationships for peak ground motion on bedrock [3; 4], which were then used to predict ground motion parameters at engineering sites. Research on attenuation relationships of peak ground motion parameters for the Loess Plateau began in the 1980s. [PERSON] et al. divided historical seismic intensity data into loess and bedrock regions [5]. By comparing data from the western United States, they derived bedrock ground motion attenuation relationships using the intensity-distance method. They suggested adjusting loess ground motion parameters to bedrock values by a factor of 0.6 or amplifying bedrock parameters by a factor of 1.67 to reflect soil amplification effects. Some researchers used administrative boundaries to conduct regional studies based on seismic intensity maps. For instance, [PERSON] analyzed seismic intensity data from the Shanxi seismic belt and established intensity attenuation relationships for the region [6]. [PERSON] et al. performed regression analysis on intensity data from 20 earthquakes of magnitude 5 or higher in Gansu Province, deriving attenuation relationships specific to the province [7]. [PERSON] et al. established separate intensity attenuation relationships for the northern Loess Plateau, the southern Qinba Mountains, and the Guanzhong Plain in Shaanxi Province. Using data from the western United States, they applied a mapping conversion method to derive bedrock attenuation relationships for these regions [8]. [PERSON] and [PERSON] analyzed 1221 strong motion records collected from soil sites in the loess regions of Shaanxi, Gansu, Qinghai, and Ningxia during the Wenchuan earthquake. Using direct fitting methods, they derived horizontal and vertical peak acceleration attenuation relationships for the Loess Plateau [9]. Subsequently, other researchers [10; 11; 12] conducted extensive studies in the Loess Plateau and other loess regions to address engineering demands or specific research needs. Existing studies show that ground motion attenuation in loess-covered areas is slower than in nearby non-loess areas. This difference becomes more pronounced for larger earthquakes and aligns with observed macro-seismic damage patterns.