Rock avalanches represent a serious risk for human lives, properties, and infrastructures. On June 24, 2017, a catastrophic landslide destroyed the village of Xinmo (Maoxian County, Sichuan, China) ...causing a large number of fatalities. Adjacent to the landslide source area, further potentially unstable masses were identified. Among them, a 4.5-million m
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body, displaced during the landslide event by about 40 m, raised serious concerns. Field monitoring and a reliable secondary risk assessment are fundamental to protect the infrastructure and the population still living in the valley. In this framework, the use of distinct element methods and continuum model methods to simulate the avalanche process was discussed. Various models (PFC, MatDEM, MassMov2D, Massflow) were used with the aim of reproducing the Xinmo landslide and, as predictive tools, simulating the kinematics and runout of the potentially unstable mass, which could cause a new catastrophic event. The models were all able to reproduce the first-order characteristics of the landslide kinematics and the morphology of the deposit, but with computational times differing by several orders of magnitude. More variability of the results was obtained from the simulations of the potential secondary failure. However, all models agreed that the new landslide could invest several still-inhabited buildings and block the course of the river again. Comparison and discussion of the performances and usability of the models could prove useful towards the enforcement of physically based (and multi-model) risk assessments and mitigation countermeasures.
Climatic change is exhibiting significant effects on the ecosystem of the Tibetan Plateau (TP), a climate-sensitive area. In particularly, winter frost, freezing events and snow avalanche frequently ...causing severe effects on ecosystem and social economy, however, few long-term winter temperature records or reconstructions hinder a better understanding on variations in winter temperature in the vast area of the TP. In this paper, we present a minimum winter (November–February) temperature reconstruction for the past 668 years based on a tree-ring network (12 new tree-ring chronologies) on the southeastern TP. The reconstruction exhibits decadal to inter-decadal temperature variability, with cold periods occurring in 1423–1508, 1592–1651, 1729–1768, 1798–1847, 1892–1927, and 1958–1981, and warm periods in 1340–1422, 1509–1570, 1652–1728, 1769–1797, 1848–1891, 1928–1957, and 1982–2007. As suggested by the comparisons with existing winter temperature series and spatial correlations with Climatic Research Unit gridded data, our reconstruction is reliable and indicative, and it can represent large-scale winter temperature variability on the southeastern TP. Furthermore, it shows an overall agreement with winter temperature from the northeastern TP on decadal to inter-decadal timescales. It also shows the possible effects of volcanic eruption and reducing solar activity on the winter temperature variability for the past six centuries on the southeastern TP.
We propose a multiscale diagonalization scheme to study disordered one-dimensional chains, in particular, the transition between many-body localization (MBL) and the ergodic phase, expected to be ...governed by resonant spots. Our scheme focuses on the dichotomy of MBL versus validity of the eigenstate thermalization hypothesis. We show that a few natural assumptions imply that the system is localized with probability one at criticality. On the ergodic side, delocalization is induced by a quantum avalanche seeded by large ergodic spots, whose size diverges at the transition. On the MBL side, the typical localization length tends to the inverse of the maximal entropy density at the transition, but there is a divergent length scale related to the response to an inclusion of large ergodic spots. A mean-field approximation analytically illustrates these results and predicts a power-law distribution for thermal inclusions at criticality.
A large and catastrophic rock avalanche occurred at the Xinmo village in the Maoxian county of the Sichuan province of China on June 24, 2017. The avalanche destroyed 64 houses and killed 10 people, ...and 73 people were reported to be missing. In this study, we focused on the contributions of six historical earthquakes to the collapse of rocks in the source area and the landslide amplification caused by the entrainment of pre-existing deposits on the landslide path. The historical earthquakes in this area contributed different levels of damage on the source rocks; particularly, the 1933 Diexi earthquake induced a few initial cracks in rocks at the crest of the steep hillslope. Under the combined time-effects of long-term weathering and gravity, the rock blocks in the source area were detached from the crest along the intersecting cracks and over-dip soft layer (namely, the sliding surface). The avalanche was amplified by the entrainment of colluvium on its path. The influence of the colluvium on the movement process of the Xinmo landslide was modelled by the GPU-based parallel discontinuous deformation analysis (DDA) method, and the effect of the impact and entrainment in the debris flow was rigorously analysed. The results indicate that the impact and entrainment can continuously increase the volume of debris flow, and the thickness of the colluvium was established to be in the range of 25.9–33.9 m based on the analysis of the deposit pattern and movement duration of the avalanche. There were numerous unstable rocks induced by historical earthquakes, at the crests of steep hill slopes in the earthquake-stricken area. With long-term damage caused by environmental factors and gravity, the failure of unstable rocks with high potential energy is likely to cause severe disasters. The excess pore water pressure likely to be present in the colluvium or deposits during impact and entrainment can considerably reduce the effective stress and degrade friction resistance along the runout path. As a result, the landslide can be intensively amplified owing to the effect of impact and entrainment under a lower friction resistance
•The volume of rock avalanche sharply increased by entrainment effects.•The rocks at the source were damaged by historical earthquakes.•The colluvium exerts different influences on the movement of the avalanche with an increase in its thickness.•Numerous earthquake-damaged rocks at the summit of mountains are hazardous.
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