Search

Seismic landslide susceptibility evaluation models are usually built on the basis of historical sample data; however, the evaluation results are often unsatisfactory when the environmental settings differ between the historical sample data region and application region. Therefore, similarity between the environmental settings is important for the application of such models. In this paper, a seismic landslide susceptibility evaluation model was first built using data from the 2008 Ms 8.0 Wenchuan earthquake-induced landslide, and the model was then used to evaluate the 2022 Ms 6.8 Luding earthquake area. In addition, the grade of susceptibility is typically represented by the landslide density, which is insufficient for capturing the details of landslides, such as their sizes, frequencies, and spatial distribution patterns. The authors therefore use a large and concentrated landslide as the susceptibility grade for the Luding earthquake area. The test results demonstrate that these two areas have similar background environments. The area under the curve (AUC) value of the receiver operating characteristics (ROC) curve of the evaluation accuracy for the model applied to the Luding earthquake area is 0.889, which indicates relatively high accuracy. Besides, the results also demonstrate that the evaluations are consistent with the disaster situation of the Moxi Platform, Wandong Village, as well as the Dagangshan Hydropower Station area. Therefore, it is reliable to apply the susceptibility evaluation model based on the Wenchuan earthquake data to the Luding earthquake area. These results show that better evaluations can be obtained based on environmental similarity tests between the areas used for historical data modeling and areas to which the models are applied. [ABSTRACT FROM AUTHOR]

Seismic landslide hazard assessment plays a very important guiding role during urgent earthquake relief. In August 2017, an Ms 7.0 earthquake in Jiuzhaigou County, Sichuan Province, China, triggered thousands of landslides. Based on the analysis of geological settings and coseismic landslide characteristics, the Newmark model is used to complete the seismic landslide hazard assessment. Three seismic motion parameters, namely, peak ground acceleration (PGA), traditional Arias intensity (Arias_P), and improved Arias intensity (Arias_C), are adopted. A publicly published coseismic landslide catalog is used as the validation samples. The results show that the coseismic landslides are mainly distributed in the deep gullies and steep mountainous slopes on the north and south sides of the epicenter. The seismic landslide hazard accuracy based on Arias_C is the best, followed by that based on PGA and Arias_P. The spatial distribution of seismic landslide hazards based on Arias_C shows an almost standard elliptical ring and is in good agreement with that of coseismic landslides. These results fully reflect the combined influence of the epicenter and seismogenic fault on landslide development. The middle seismic landslide hazard and over are mainly located at areas with seismic intensity of VII degree and above. The Arias intensity is very suitable for rapid seismic landslide hazard assessment in emergency situations. The study results can provide scientific and technological support for rapid earthquake relief and have reference significance for future seismic landslide hazard assessment. [ABSTRACT FROM AUTHOR]

On May 21, 2021, at 21:48, the Ms6.4 Yangbi earthquake struck Dali prefecture, Yunnan province, China; the maximum PGA reached 714.78 gal, causing 37 casualties and infrastructures damage. A field investigation demonstrated that seismic landslides were concentrated along the G56 Hangrui and Dayangyun highways, classified as local rock falls and shear slides. The shear slides were more severe than the local rock falls and were located along the Dayangyun highway, which was still under construction when the earthquake occurred, severely impacting following engineering activities. Typical shear slides caused by the earthquake were selected for detailed investigations; electrical resistivity topography (ERT) was conducted to study the failure mechanism. The ERT results indicated that the sliding surface was located at the interface between the overburden layer and the underlying rock stratum. The slope failures along the Dayangyun highway were characterized by several tensile cracks on the rear edge, a relatively short displacement, and an accumulation at the toe of the excavated slope where reinforcement measures had not yet been completed. The combined effect of engineering activities and a geological structure provided favorable conditions for slope failure. In addition, seismic motion triggered the landslides; however, engineering activity was a specific and significant factor contributing to the shear slides during the Yangbi earthquake. Excavation and incomplete construction reduced the stability of the overburden soil layer. Although the scale of the seismic landslides in the Yangbi earthquake was generally small, the coming rainy season after the earthquake may contribute for sliding again. [ABSTRACT FROM AUTHOR]

This work represents a regional potential seismic landslide hazard assessment for the Tianshui area, southeastern Gansu Province, China. The peak ground accelerations for two specific seismic scenarios (Ms 7.0 and 8.0) are estimated through empirical attenuation relationships. They are then combined with the slope threshold accelerations to calculated cumulative displacements through the Newmark’s sliding rigid-block model. Potentially unstable areas are identified based on the predicted Newmark displacement. The results show that both of the scenarios are capable of producing widespread slope instabilities, mainly loess landslides in the near-fault region, and that the Ms 7.0 earthquake would induce more slope instabilities around Tianshui city. The high-risk zones are concentrated mainly in the loess or mudstone areas with slope greater than 30°, especially on the banks of the Wei River, Xi River, and Niutou River, and pose a threat to the Longhai Railway line and the surroundings of Tianshui city. The potential damage to traffic networks and to built-up areas in Tianshui city is also mapped. These maps represent a preliminary assessment that can be utilized by local government to define the seismic landslide hazard better for future detailed risk evaluation, emergency plans, and engineering design. [ABSTRACT FROM AUTHOR]