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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]

On May 5, 2014, an earthquake with a magnitude of Mw 6.1 (the largest earthquake in Thailand so far) occurred in Chiang Rai of the Golden Triangle area in northern Thailand. We had an opportunity to conduct field survey immediately after the earthquake. Serious damage to buildings and casualties of lives were observed, and the estimated Maximum Mercalli Intensity (MMI) of the earthquake is VIII (evaluated according to the MMI scale of the Chinese Standard). No long continuous ground ruptures were produced during the earthquake, but in the epicenter (commonly within MMI VIII extent), massive small linear ruptures (usually several tens of meters long) developed and displayed intriguing structural features, offsetting many roads several centimeters left laterally on NE trending cracks or offsetting right laterally on NW trending ones. The focal mechanism solution of earthquake shows that this is a pure strike‐slip event, and two nodal planes in NW and NE directions had the same motion senses respectively as those of breakage associated with the earthquake. The long axis of the isoseismals and aftershock distributions are in NE direction, which is consistent with the strike of Luang Namtha fault. The 230‐km‐long Luang Namtha fault which starts from the border of China and Laos, runs through northern Laos, and terminates at Chiang Rai of Thailand is predominated by left‐lateral strike‐slip and active in late Quaternary, and two earthquakes over Ms 6.0 occurred along the fault in 1925 and 2007 respectively. This Mw 6.1 earthquake occurred at the southwestern end of the fault. All related features such as evident structural rupturing, elongated orientation of MMI and aftershock distribution, as well as the location of the epicenter, suggest that the Luang Namtha fault may be responsible for the 2014 Northern Thailand earthquake. [ABSTRACT FROM AUTHOR]

The 2008 Mw 7.9 Wenchuan, China, earthquake produced many damaging landslides in the Longmenshan region along the eastern margin of the Tibetan Plateau, China. Among the thousands of reported landslides, some are geologically notable because of their close spatial relationship to local fault rupture complexities. The Leigu landslide is particularly interesting because it formed at a restraining bend along the Beichuan-Yingxiu fault system in a structural position that favored hill-slope collapse because of a variety of preexisting structural and geomorphological conditions. The 2008 landslide reactivated an older landslide that is indicated by a preserved paleo-scarp upslope from the main 2008 event scarp. Our field and analytical results coupled with a review of existing geological information on the region indicate that the landslide site is located between two regional folds with opposing plunge directions and that the restraining bend is the displacement transfer zone between two parallel, but offset segments of the Beichuan-Yingxui Fault system. In addition, NE-oriented steep joints were reactivated as slip surfaces in the upper slopes of the landslide area within an anticline hinge zone that focuses vertical uplift. Steep valley walls due to incision of the antecedent Laochangkou River and abundant rainfall during the earthquake period, combined with intense seismic acceleration were contributing factors to the landslide event. During the earthquake, approximately equal components of strike-slip and SE-directed thrusting occurred on surface ruptures within the bend, offsetting older landslide deposits and man-made structures. Field results indicate that sliding was facilitated by loose unconsolidated materials from the previous landslide that were remobilized above a soft, low-friction basal slip surface. The Leigu landslide provides an important case study for evaluating potential landslide hazards close to active fault systems where complex 3-D structural geometries and high-relief, steep terrain combine to generate significant ground instability during large magnitude earthquakes. [ABSTRACT FROM AUTHOR]

Due to complicated structures and discontinuities in surrounding rock mass, existing empirical failure criteria cannot meet the requirements of engineering practice such as tunnels. To improve estimation accuracy on the strength of rock mass with joints, a modified chart of the Geological Strength Index using Hoek-Brown criteria was further tested to estimate rock mass strength [Lin et al. (2014) Bull Eng Geol Environ 4(73):1245-1258], and, in this paper, new strength estimation equations for jointed rock mass were then modified based on a large dataset obtained from Chinese projects. Here, standard drilling time is first introduced and described in this study, and then used as a parameter to estimate rock strength. Different empirical formulas based on joint density, rock mass classification, Hoek-Brown criteria, and elastic wave velocity are thus used to estimate rock mass strength by using data from the Jiubao tunnel. The results estimated based on different empirical formulas were similar, indicating that the modified assessment method presented in this paper can be used to estimate rock mass strength under certain circumstances. Cross-correlation of different empirical methods provides significant confidence in predicted rock mass strength calculations. [ABSTRACT FROM AUTHOR]

Risk assessment and minimisation of environmental hazards are critical issues to consider in the geotechnical engineering projects. A case of highway pavement seepage induced by groundwater, at a locality along the section of Hua-Qing Highway of Guangdong Province, China, is presented for environmental hazard analysis and effective remediation. The environmental hazard analyses were based on in situ hydrogeologic investigation, rock–soil testing and integrated environmental understanding. The analyses indicate that the highway seepage was caused by elevation of groundwater hydraulic pressure in low permeable strata near the highway pavement, which was controlled by landform, hydrology, weather and road structure. The risk source of groundwater ‘flooding’ was the groundwater and surface water in the ring-like valley around Fenshui Village. A blind-ditch system for effective remediation of the pavement seepage hazard was proposed and successfully implemented by declining groundwater table near the highway based on the comprehensive assessment of various conditions. This geotechnical accident shows that the role of groundwater is an essential factor to consider in the geotechnical and environmental engineering studies and multidisciplinary effort for risk assessment of environmental hazards is important under current global climate change condition. [Copyright &y& Elsevier]