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Debris flow risk is growing with the current increases in landscape exploitation and extreme precipitation events associated with global warming. Insurance is an efficient approach to cope with disasters. Based on the quantitative assessment, the debris flow hazard was obtained by a dynamic run-out model (FLO-2D), and the pure risk premiums of debris flow disaster were rating in a high-risk region (Anzhou) in Sichuan, China. Simulation results indicated that disastrous debris flows would reoccur every 5 years on average under the contemporary climatic and geological conditions of the study area. The mountain region experienced a wider area affected by debris flows than plains and hills; however, its area affected by low debris flow depth (d

Although time-averaged shear wave velocity to the depth of 30 m (Vs30) is an important indicator of earthquake site effects, it is difficult to obtain. Several proxies have been used either individually or in combination to infer Vs30 values during seismic hazard estimation under limited observational conditions. Sichuan Province is an area highly prone to earthquakes. Complex geological structures and lack of drilling sites mean that it is particularly important to establish a suitable approach for the estimation of Vs30 values for site classification. This study compared the application of three proxy-based approaches—geology-based, topographic slope-based, and terrain-based—to the estimation of Vs30 values in Sichuan Province. The results revealed that the residual between the measured logVs30 values and the estimations derived from the terrain-based approach was smallest, indicating best predictability. Stability analysis of the three approaches also showed that the terrain-based approach performed best. However, its performance in the plain area was poor, that is, the Vs30 values were mostly underestimated. This might indicate that the old strata, hard rock, and alluvial deposits formed by Quaternary glacier sediments were not identified appropriately in the plain area, highlighting the need for localized corrections.

The rapid urbanization of China generated not only dozens of megacities but also a great number of surrounding small and medium-sized cities. The utter lack of seismic risk assessments for small and medium-sized cities is emerging as a potential threat. A seismic risk evaluation of a medium-sized city, Jiangyou, is presented with the modified vulnerability index method (VIM), based on the investigation of 6369 buildings for a scenario corresponding to the destructive historical earthquake of May 12, 2008 (MW 7.9). The population-time-land (PTL) model is used to estimate the human deaths (MD) and resettlement population (MR). The direct economic loss from physical damage to buildings is calculated. The results show that the modified VIM not only can indicate that the distributions of building seismic vulnerability and direct economic loss are closely related with city plans, but reflect the seismic performance characteristics of buildings and the huge differences in seismic consequences under different time scenarios. Evaluating seismic risk in small and medium-sized cities will support accurate and comprehensive seismic risk mitigation strategies setting in similar rapid urbanization areas under earthquake threats.

Slope geohazards, which cause significant social, economic and environmental losses, have been increasing worldwide over the last few decades. Climate change-induced higher temperatures and shifted precipitation patterns enhance the slope geohazard risks. This study traced the spatial transference of slope geohazards in the Qinghai-Tibet Plateau (QTP) and investigated the potential climatic factors. The results show that 93% of slope geohazards occurred in seasonally frozen regions, 2.6% of which were located in permafrost regions, with an average altitude of 3818 m. The slope geohazards are mainly concentrated at 1493–1988 m. Over time, the altitude of the slope geohazards was gradually increased, and the mean altitude tended to spread from 1984 m to 2562 m by 2009, while the slope gradient varied only slightly. The number of slope geohazards increased with time and was most obvious in spring, especially in the areas above an altitude of 3000 m. The increase in temperature and precipitation in spring may be an important reason for this phenomenon, because the results suggest that the rate of air warming and precipitation at geohazard sites increased gradually. Based on the observation of the spatial location, altitude and temperature growth rate of slope geohazards, it is noted that new geohazard clusters (NGCs) appear in the study area, and there is still a possibility of migration under the future climate conditions. Based on future climate forecast data, we estimate that the low-, moderate- and high-sensitivity areas of the QTP will be mainly south of 30° N in 2030, will extend to the south of 33° N in 2060 and will continue to expand to the south of 35° N in 2099, we also estimate that the proportion of high-sensitivity areas will increase from 10.93% in 2030 to 14.17% in 2060 and 17.48% in 2099.