A Mw7.8 earthquake struck Turkey on 6 February 2023, causing severe casualties and economic losses. This paper investigates the characteristics of strong ground motion and seismogenic fault of the earthquake. We collected and processed the strong ground motion records of 379 stations using Matlab, SeismoSignal, and Surfer software: Matlab (Version R2016a), SeismoSignal (Version 5.1.0), and Surfer (Version 23.0.15), and obtained the peak ground acceleration (PGA) contour map. We analyzed the near-fault effect, the fault locking segment effect, and the trampoline effect of the earthquake based on the spatial distribution of PGA, the fault geometry, and slip distribution. We found that the earthquake generated a very strong ground motion concentration effect in the near-fault area, with the maximum PGA exceeding 2000 cm/s². However, the presence of fault locking segments influenced the spatial distribution of ground motion, resulting in four significant PGA high-value concentration areas at a local dislocation, a turning point, and the end of the East Anatolian Fault. We also revealed for the first time the typical manifestation of the trampoline effect in this earthquake, which was characterized by a large vertical acceleration with a positive direction significantly larger than the negative direction. This paper provides an important reference for understanding the seismogenic mechanism, damage mode, characteristics, and strong earthquake law of the Turkey earthquake.

Due to its special material composition, formation environment, and special structure, loess usually shows different engineering and dynamic characteristics from ordinary soil. Based on previous research results, this paper studies the Haiyuan loess. It is found that: (1) the variation coefficients of various physical properties (except for the liquid index) of loess in the region are relatively stable, but the mechanical properties are relatively discrete; (2) the correlation among natural water content, void ratio, and density is high, but the correlation between mechanical properties is poor; (3) the consolidation ratio, effective confining pressure, and dynamic shear modulus ratio change in direct proportion, while the damping ratio changes in the opposite direction with increasing shear strain; and (4) in this paper, the recommended model of shear wave velocity and burial depth of loess in the study area is given. Compared with the example, the error is smaller and more reliable. (5) The characteristic period of the seismic response spectrum of the loess soil layer is not sensitive to the change in the damping ratio, and the change amplitude is small.

The increase of pore water pressure under a dynamic load is an important reason for the vibration liquefaction of saturated sand. Therefore, studying the dynamic pore water pressure model of tailings sand plays an important role in the seismic liquefaction analysis of tailings ponds. In this paper, the dynamic pore water pressure development characteristics of tailings fine sand and tailings silt in a tailings pond with the centerline method are studied by dynamic triaxial tests. The research results show that the liquefaction dynamic pore pressure ratio of tailings fine sand shows a trend of "rising–smooth–rising" with increasing vibration frequency ratio, and the liquefaction dynamic pore-pressure ratio of tailings silt shows an approximate linear and stable increasing trend. According to the development law of dynamic pore pressure, a new tailings sand pore pressure stress model is proposed in this paper, and the fitting effect is compared with four different pore pressure models, which verifies the applicability of the new model to predict the growth of dynamic pore pressure in tailings and silt.

This study collected acceleration records and station reports from 379 strong-motion stations triggered by the M_w7.7 earthquake in Pazarcik, Türkiye, on 6 February 2023. A total of 451 horizontal and 194 vertical strong-motion acceleration records with complete waveforms and reasonable data were selected to establish appropriate equations for predicting seismic parameters. Two iterative algorithms, specifically the optimization algorithm and orthogonal distance regression, were employed to formulate prediction equations for PGA and EPA in the NS (north–south), EW (east–west), and vertical directions. Furthermore, a comparative analysis of the attenuation curves for PGA and EPA was conducted within the vertical and horizontal directions. The results indicated that the observed and predicted values of vertical PGA and EPA at the same fault distance were approximately 0.577–0.673 times those of horizontal PGA and EPA. The ratio range calculated in our study aligns closely with previous research results, slightly more than 2/3 only in the vicinity of fault zones. The analysis demonstrated that the horizontal PGA value of the soil site at the same fault distance was approximately 1.46 times that of the bedrock site, while the vertical PGA value was only 1.12 times. The comparison of attenuation relationships revealed that within the fault distance range of 20 km to 100 km, the horizontal PGA of the Wenchuan earthquake was approximately 1.26–2.16 times that of the Pazarcik earthquake, and the ratio increased with an increasing fault distance.

This study aims to explore the differences between the loess and landslide deposits, focusing on aspects such as particle distribution, consolidation characteristics, and the dynamic shear modulus. Through a series of experiments, the research reveals the similarities and differences between these two entities, yielding several key findings. Firstly, the process of landsliding disrupts the original structure of the loess, resulting in a reduction in porosity and a densification of the soil. Additionally, the movement and sorting of particles during the landslides cause variations in particle size distribution across different sections of the landslide deposits. Secondly, the landslide process not only alters the soil’s structure but also changes the particle sizes within the loess. Particle wear and sieving results in the transformation of larger particles into smaller ones, leading to a more uniform particle size distribution. This shift in the structure and particle size directly impacts the consolidation characteristics of landslide deposits, resulting in a substantial reduction in the compression coefficient. Despite undergoing consolidation for decades, the middle and lower sections of the landslide deposits still exhibit under-consolidation. Although the differences in the maximum dynamic shear modulus between the loess and landslide deposits at varying depths are relatively minor, differences in the porosity and consolidation characteristics lead to faster decay rates of the dynamic shear modulus for the latter. The study also highlights a reduction in the water sensitivity of the maximum dynamic shear modulus within the landslide deposits. Based on the experimental results, a predictive model is proposed, utilizing the A and m values to estimate the maximum dynamic shear modulus of both the loess and landslide deposits. In conclusion, this research uncovers the impact of landslide processes on the structure and properties of the loess, providing an insightful understanding into the disparities between these two entities.