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The Mw 6.3 Yutian earthquake, occurred in northwestern Tibet on 25 June 2020, is one of the major events sequentially occurring in the region following the 2008 Mw 7.2, 2012 Mw 6.2, and 2014 Mw 6.9 earthquakes, and is of great significance for studying the tectonic activity and assessing future seismic hazards in the region. In this study, we used Sentinel‐1 Synthetic Aperture Radar images to retrieve co‐ and post‐seismic deformation and to investigate the coseismic rupture behavior of the fault and the mechanisms of postseismic deformation. Based on the slip models of recent four nearby major earthquakes, we explored the local stress evolution, triggering mechanism of the 2020 event and future regional seismic hazards. Postseismic modeling reveals that afterslip on fault patches surrounding the ruptured co‐seismic patches is the main mechanism responsible for the near‐field deformation, with the poroelastic rebound relaxation only accounts for maximumly 25% of the ground displacement and limited impact on the overall deformation pattern. The Coulomb failure stress changes (ΔCFS) suggest that the 2020 Yutian earthquake was inhibited by the 2008 Mw 7.2 earthquake but facilitated by the 2012 Mw 6.2 and 2014 Mw 6.9 earthquakes, resulting in an overall ΔCFS with a large lateral gradient on the 2020 fault. Stress concentrations on nearby major faults indicate increasing chances of seismic hazards in the eastern section of the Altyn Tagh fault at 82.8°E, the western section of the Guozha Co fault at 81.5°E and the entire section of the Ashikule fault. Plain Language Summary: The 2020 Mw 6.3 Yutian earthquake is one of the major events sequentially occurred following the 2008 Mw 7.2, 2012 Mw 6.2, and 2014 Mw 6.9 earthquakes in Yutian County. As large earthquakes result in stress perturbations altering regional seismicity, it provides great opportunity for studying the regional tectonic activity and assessing future seismic hazards. In this study, we investigated the coseismic rupture behavior of the 2020 earthquake and the mechanisms of postseismic deformation observed by radar observations. We also explored the local stress evolution, triggering mechanism of the 2020 event and future seismic hazards. Postseismic modeling indicates that afterslip is responsible for most of the near‐field deformation, with the poroelastic rebound effect contributing only a small portion. Earthquakes prior to 2020 have generated considerable stress perturbations with complex patterns which may have triggered the 2020 Yutian earthquake. Stress concentrations on nearby faults indicate that future attention should be paid in the eastern section of the Altyn Tagh fault at 82.8°E, the western section of the Guozha Co fault at 81.5°E and the entire section of the Ashikule fault. Key Points: The afterslip and poroelastic rebound mechanisms were examined to explain the observed postseismic deformationPrevious major events caused complex stress changes on the fault ruptured in 2020 with along‐strike gradients from positive to negativeStress concentrations on major nearby faults were calculated and future seismic hazards were evaluated [ABSTRACT FROM AUTHOR]

This study highlights the importance of the effects of spatial tourism. Using panel data of 135 Wenchuan earthquake-affected counties from 2008 to 2018, this study employs the dynamic spatial Durbin model to examine the spatial effects of tourism development on post-disaster economic resilience and compares the differences in the tourism-growth nexus between severe disaster-affected counties and general disaster-affected counties. The empirical results show that tourism development contributes to economic resilience for general disaster-affected counties, which supports the tourism-led growth hypothesis, whereas there is an inverted U-shaped relationship for severely disaster-affected counties. Furthermore, the spatial spillover effects of tourism are insignificant. Plausible explanations for these results are discussed, and policy suggestions are provided. [ABSTRACT FROM AUTHOR]

The occurrence of destructive earthquakes is a small probability event, that is, the seismic samples are extremely imbalanced, which increases the difficulty of earthquake prediction. The existing earthquake prediction methods rarely adopt sample imbalance technology, and the prediction results are not good enough. Therefore, this study proposes a novel immune optimization inspired Numerical Differential Artificial Natural Killer Cell Algorithm (NDANKA) for earthquake prediction. First, based on the signals collected by our developed Acoustic and Electromagnetic Testing All in one system (AETA), historical record and precursor data are combined as the data source of our proposed model; then, the numerical differential artificial-based natural killer cell method is adopted to construct time-series Synthetic Minority Over-sampling Technique; moreover, an artificial antigen presenting cell approach is introduced to predict earthquakes; finally, the stochastic gradient descent method is adopted to optimize the parameters of the proposed algorithm. Through experiments in Sichuan and surroundings, the results demonstrate that the proposed NDANKA outperforms the state-of-the-art earthquake prediction approaches. Meanwhile, a hypothesis testing is accomplished. [ABSTRACT FROM AUTHOR]

In the neo-deterministic seismic hazard assessment (NDSHA) evaluation, great-earthquake-prone areas (GEPAs) play an important role in defining the 'controlling earthquakes' or 'scenario earthquakes'. When considering great earthquakes, their finite rupture attributes, which contribute to determine the strong ground motions and intensities, have to be taken into account. For continental earthquakes in China, the great earthquakes are located mainly within the boundary zones of the 'tectonic blocks'. The 'tectonic block' model indicates the focal mechanisms and some finite rupture attributes of the great earthquakes within the boundary zones. Accordingly, in the NDSHA for China, it is both necessary and feasible for the GEPAs to consider the finite rupture attributes of great earthquakes. The Sichuan-Yunnan border in southwest China has been taken as an example to naturally develop the originally used circular shape of GEPAs into one with more degrees-of-freedom, better reflecting the possible rupture processes of the considered earthquakes. [ABSTRACT FROM AUTHOR]

A two-step model based on MODIS remote sensing data and statistical inversion method for calculation of high resolution ground solar radiation is constructed. Firstly, monthly solar radiation percentage of grid points is calculated based on the correlation between remote sensing cloud cover and percentage of sunshine at ground level; secondly, the solar radiation of grid point is calculated based on the correlation between percentage of sunshine and solar radiation. Finally, this model is used to calculate the surface solar radiation with 1km grid resolution in Sichuan province, and the results are evaluated by actual total radiation from six representative radiation stations. The results show that the annual total radiation in Sichuan province ranges from 3102MJ·m-2 to 6659MJ·m-2. Among it, the lowest value occurs in the southeast of Sichuan Basin and the highest value occurs in the Western Sichuan Plateau. The calculated monthly solar radiation of the six representative stations are basically consistent with the observation results. Specifically, the absolute errors of calculated annual radiation are less than 100MJ·m-2 and the relative errors are less than 2%, which shows that the proposed model has high simulation accuracy and can be used to calculate the surface solar radiation in Sichuan province. [ABSTRACT FROM AUTHOR]

The living heritage approach seeks to link heritage properties with the living dimensions attributed by local communities - tangible and intangible heritage. However, how living heritage can be further understood and managed in post-disaster traditional settlements has yet to be explored adequately. This paper discusses the concept of living heritage embedded in post-earthquake planning and reconstruction of traditional settlements in Jiuzhaigou Valley, a World Heritage property in Sichuan Province. The thematic analysis method is employed to conduct both deductive and inductive content analysis of governmental administrative documents on post-earthquake reconstruction policies and practices. The results demonstrate that the continuity of heritage and the continuity of community are the two essential attributes conceptualizing living heritage by developing a people-centered approach to resilience-building in post-disaster traditional settlements. The paper broadens the concept of living heritage by incorporating the discussion of heritage and traditional settlements into a post-disaster context. The living heritage approach can be further elaborated into an integrated heritage management approach relying on community values and empowerment, to promote urban and rural conservation and urbanization policy-making and practices worldwide. [ABSTRACT FROM AUTHOR]

In this study, the post-earthquake economic recovery of the most severely affected areas in the 2008 Wenchuan earthquake is analyzed. First, a new analysis method that uses the economic data in Sichuan Province as the comparison standard is proposed. Then, based on the economic data of the most severely affected areas and Sichuan Province from 2003 to 2019, the post-earthquake economic recovery of the most severely affected areas is analyzed, and the results of the analysis are compared with those of the synthetic control method and the gray prediction model. Finally, the recovery path and its influencing factors are analyzed. The main findings are as follows: (1) The recovery of the post-earthquake economy varies among regions. Only the GDP per capita of An County and Pengzhou City had recovered to the pre-earthquake level by 2019. (2) The proposed method is highly similar to the synthetic control method in determining the recovery process and recovery time of the post-earthquake economy but differs significantly from the gray prediction model in the results of the analysis of the long-run economic recovery. (3) The post-earthquake economic recovery of the most severely affected areas shows a variety of recovery paths. The rapid and gradual decrease in the normalized gross investment in fixed assets (GIFA) per capita after the reconstruction period led to the economic recovery of the most severely affected areas into different recovery paths, and the significant increase in the normalized GIFA per capita and normalized retail sales of consumer goods (RSCG) per capita may lead to economic recovery breaking the equilibrium state and entering a new recovery path. Some discussions on the comparison of the proposed method, the synthetic control method and gray prediction model are also given as well as the economic recovery path. [ABSTRACT FROM AUTHOR]

Global climate change has increased severe torrential hazards, particularly debris flows in mountainous regions. After floods and earthquakes, debris flows are the most devastating natural hazard in the world. The effects of debris flow on human life and built environments necessitate reconsidering current infrastructure planning, engineering, and risk management practices. Hence, the vulnerability of elements at risk is critical for effective risk reduction systems. Therefore, this article reviews the existing physical vulnerability approach of infrastructure, particularly building toward debris flow hazards in the last 20 years. Furthermore, uncertainties associated with the vulnerability assessment and their quantification techniques have also been discussed in detail. It was found that matrices, curves, and indicators have been extensively used for vulnerability assessment approaches in the last two decades. However, if aleatory and epistemic uncertainties are not quantified or conserved in the vulnerability assessment process, it makes the system inefficient and unreliable. Moreover, data requirements, strengths, and weaknesses of approaches presented herein are highlighted with case studies. Finally, a thorough discussion on future needs in the field of risk assessment methodologies is highlighted by considering uncertainties into account. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to assess the impact of the Ms7.0 Jiuzhaigou earthquake that occurred on 8 August 2017 on vegetation, the Carnegie-Ames-Stanford Approach (CASA) model was adopted to estimate the vegetation net primary productivity (NPP) of Jiuzhaigou Valley, one of the World Heritage Sites, in July, August and September from 2015 to 2019. Then the characteristics of the impact of different earthquake-induced geohazards on vegetation were discussed, and a vulnerability-resilience assessment system concerning the seismic intensity was proposed. The results show that the NPPmax and NPPmean values in Jiuzhaigou Valley first decreased and then increased and were 151.5–261.9 gC/m2 and 54.6–116.3 gC/m2, respectively. The NPP value of more than 70% area was 90–150 gC/m2 in July. In August, the NPPmean values decreased, and the areas with lower values became larger; the NPPmean values of most areas affected by geohazards were 60–150 gC/m2. During the earthquake, the NPPmean values of areas hit by geohazards sharply declined by 27.2% (landslide), 22.4% (debris flow) and 15.7% (collapse) compared with those in the same month in 2016. Vegetation in debris flow zones showed a stronger recovery, with a maximum NPP value increase of about 23.0% in September 2017. The vegetation gradually recovered after the earthquake, as indicated by the uptrend of the NPP values in the corresponding period in 2018 and 2019. In general, the reduction magnitude of NPP values decreased year by year in comparison to that in 2015 and 2016, and the decrease slowed down after the earthquake. The vulnerability and resilience index corresponding to the three seismic intensity ranges were 0.470–0.669 and 0.642–0.693, respectively, and those of Jiuzhaigou Valley were 0.473 and 0.671, respectively. The impact coefficient defined to represent the impact of the earthquake on NPP was 0.146–0.213. This paper provides a theoretical reference and guidance for the impact assessment of earthquakes on the ecosystem. [ABSTRACT FROM AUTHOR]

We establish a reasonable 3D complex fault model. The Global Positioning System (GPS) data is adopted to reproduce the slip distribution of the 2008 Mw7.9 Wenchuan earthquake. Utilizing the nonnegative least square method, the slip distribution of the fault plane is recovered. The results are as follows: (1) The released seismic moment of Wenchuan earthquake is 0.959 × 10 21 N · m. The deep of the rupture is mainly within 15 km. (2) The rupture mainly occurred along the Beichuan fault, indicating that the Beichuan fault is the main rupture fault. On the southern section of the Beichuan fault, the rupture is concentrated from Yingxiu to Longmenshan and from Yuejiashan to Qingping areas, with mainly thrust slip. On the northern section of the Beichuan fault, the slip is concentrated near the surface of Beichuan and Nanba areas, with thrust and strike slip. On the Pengguan fault, the slip is mainly located near Hanwang with thrust and strike slip. (3) The GPS data are useful for defining the slip in the shallow part but are useless to determine the slip in the deep part. Meanwhile, the time information of the rupture cannot be reproduced. [ABSTRACT FROM AUTHOR]

The earthquake and its secondary geological disasters have some long-term effects on vegetation recovery, and the spatiotemporal differentiation of vegetation coverage in earthquake-stricken areas are often not valued by researchers. Beichuan County in Sichuan Province is the worst-hit area during Wenchuan earthquake, tracking the vegetation coverage in this disaster area can provide feedback for post-earthquake ecological restoration. Based on remote sensing (RS) and Geographic information system (GIS), this paper relies on dimidiate pixel model (DPM) and vegetation coverage transfer matrix to explore the vegetation coverage of the earthquake worst-hit area. The results show that the overall level of vegetation coverage in Beichuan county is high, and earthquakes are dominant in the areas with high vegetation coverage. Besides, earthquake can do most severe damages to the areas with high vegetation coverage, followed by medium damage impacting to the areas with medium vegetation coverage, but the damage of other areas are relatively small. From 2007 to 2020, the average vegetation coverage in Beichuan County decreased from 0.835 in 2007 to 0.755 in 2008, then gradually recovered to 0.826 in 2020, experiencing a sharp decline and then a steady increase. The recovery of vegetation coverage is improved over time, but the spatiotemporal differences of the recovery process are obvious. Elevation has the largest driving force on vegetation coverage (q = 0.569, p less than 0.001), followed by temperature and rainfall; the interaction between factors has a significant increasement in the spatial differentiation of vegetation coverage, indicating that vegetation coverage is a combination result of multiple factors. The research findings can help construct the scientific management of the eco-environment in the disaster area, it can also help builda medium to long-term ecological restoration plan according to the variation in vegetation coverage. [ABSTRACT FROM AUTHOR]

The finite-fault stochastic method was applied to simulate the Mw 6.9, 2008 Iwate-Miyagi earthquake at 44 selected KiK-net sites using EXSIM computer code. To investigate the effects of source characteristics on the simulated results, three models were considered: two models with prescribed slip distribution (Model 1 and Model 3) and a model with random slip distribution (Model 2). S-wave regional attenuation indicates an obvious difference between fore-arc and back-arc regions which are formed by volcanic front. Site amplification was determined by corrected surface to borehole spectral ratio and Quarter wavelength methods. The high-frequency decay parameter (kappa) was estimated to be 0.0473 s. The value of 16 MPa for stress drop was calculated by minimizing the absolute residual of 5% damped pseudo-spectral accelerations (PSA). Comparison of the observed and simulated PGAs and PSAs was performed to investigate the capability of our finite-fault models. The residual models represent that the simulated results by Model 2 are in good agreement with the observations in f < 3 Hz, while the other models can better simulate higher frequency motions. We also focused on the effects of slip patches sitting on the fault plane on near-field stations placed in the directions of slip propagation. For these stations, the simulated results by Model 1 and Model 3 were preferred over those of Model 2. Finite-fault models successfully interpreted the real forced motions to AKTH04 where the recorded peak values were abnormal for non-seismological reasons. Finally, the comparison of intensity measures with the GMPEs showed agreement. [ABSTRACT FROM AUTHOR]

The 5.12 Wenchuan earthquake in 2008 led to a large number of loose deposits on the slope on both sides of the gully in the formation area. Under the triggering action of heavy rainfall, the previously unrecognized slope loose source in formation areas easily failed and started earlier than the overall start of the gully debris flow, which has practical significance for realizing the early warning of the gully debris flow starting. The special loose source conditions and postearthquake geological environment change the hydraulic mechanism of traditional debris flow start-up, which brings great difficulties to the monitoring and early warning of postearthquake debris flows. Therefore, based on hydraulics, on the premise of building a hydraulic model of groundwater level change of loose slope accumulation body, the characteristics and rules of groundwater level change are analyzed with the aid of hydraulic seepage theories, and the action characteristics of hydrodynamic pressure and hydrostatic pressure on the accumulation body are quantitatively studied. Based on field exploration data and average slope gradient, we divided the accumulation body in a reasonable manner; completed the sliding force, anti-sliding force and residual-sliding force mechanical expression and establishment; and performed a slope stability analysis. The research results show that the slope starting mode is divided into the thrust-type landslide and the retrogressive landslide mode of the subsection disintegration. The hydraulic deposit mechanism analytical results can also reverse the critical rainfall condition of slope failure. Finally, taking the Yindongzi gully in Dujiangyan as an example, the hydraulic mechanism of typical slope deposits in the formation area was analyzed and combined with the historical debris flow events in the study area to verify the physical simulation test, which was consistent with the field investigation results after the disaster. [ABSTRACT FROM AUTHOR]

The article presents a study on the number of wild multilevel societies of the endangered Rhinopithecus roxellana, also known as the golden snub-nosed monkey, in China. Topics discussed include threats to the existence of this species, an increase in the number of the species from 1992 to 2018, and the implications of the study for environmental planning and sustainable development for the conservation of the species and its habitat.

Land surface temperature (LST) is a key parameter in the study of surface energy balance and climate change from local through to global scales. Vegetation has inevitably influenced the LST by changing the surface properties. However, the thermal environment pattern in the Yangtze River Basin (YRB) still remains unclear after the implementation of large-scale ecological restoration projects. In this study, the temporal and spatial variation characteristics of LST were analyzed based on the Theil–Sen estimator, Mann–Kendall trend analysis and Hurst exponent from 2003 to 2021. The relationships between vegetation and LST were further revealed by using correlation analysis and trajectory-based analysis. The results showed that the interannual LST was in a state of fluctuation and rise, and the increasing rate at night time (0.035 °C·yr−1) was faster than that at day time (0.007 °C·yr−1). An obvious cooling trend could be identified from 2007 to 2012, followed by a rapid warming. Seasonally, the warming speed was the fastest in summer and the slowest in autumn. Additionally, it was found that autumn LST had a downward trend of 0.073 °C·yr−1 after 2015. Spatially, the Yangtze River Delta, Hubei province, and central Sichuan province had a significant warming trend in all seasons, except autumn. The northern Guizhou province and Chongqing showed a remarkable cooling trend only in autumn. The Hurst exponent results indicated that the spring LST change was more consistent than the other three seasons. It was found by studying the effect of land cover types on LST changes that sparse vegetation had a more significant effect than dense vegetation. Vegetation greening contributed 0.0187 °C·yr−1 to the increase in LST in winter, which was spatially concentrated in the central region of the YRB. For the other three seasons, vegetation greening slowed the LST increase, and the degree of the effect decreased sequentially in autumn, summer, spring and winter. These results improve the understanding of past and future variations in LST and highlight the importance of vegetation for temperature change mitigation. [ABSTRACT FROM AUTHOR]

The 2008 Mw 7.9 Wenchuan earthquake, one of the largest continental intraplate events instrumentally recorded, struck the central part of Sichuan Province in southwestern China causing great destruction and loss of life but also providing a wealth of seismological data, geodetic measurements, and tectonic observations. The Wenchuan earthquake ruptured two northwest‐dipping imbricate oblique reverse faults along the middle segment of the Longmenshan fault zone—a northeast‐trending thrust belt located at the boundary between the Tibetan Plateau and the Sichuan Basin. In this study, a hybrid approach that combines deterministic modeling at low frequencies with stochastic modeling at high frequencies is used to simulate broadband ground motions at 52 strong‐motion stations and 506 geodetic sites in the vicinity of the causative fault. The low‐frequency components of the synthetic ground motion are simulated using an extended kinematic source model embedded in a layered medium, whereas the high‐frequency components are generated using a stochastic finite‐fault model. The two independently derived ground‐motion components are then combined using matched filtering at a crossover frequency of 0.8 Hz to generate broadband ground‐motion time histories and response spectra. The temporal and spectral characteristics of the synthetic and recorded ground motions at the 52 strong‐motion stations are compared and the effect of soil nonlinearity on the simulated ground motions is investigated through 1‐D nonlinear site response analysis. Finally, the simulated permanent ground displacements at the 506 geodetic sites are evaluated against geodetic observations and the peak amplitudes of the synthetic ground motions at the same locations are compared with predictions of empirical ground‐motion models. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Resources is the property of Geology & Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Featured Application: Resource and environmental effects of the Tibetan Plateau. Long-term stress accumulation influenced by coseismic stress changes and postseismic viscoelastic relaxation is considered critical to triggering giant earthquakes. Nevertheless, how the stress increase is interrupted by aftershocks and how it influences the megaseismic cycle remain enigmatic. In this study, based on the Mohr–Coulomb failure criterion at the nucleated segments of the 2008 great Sichuan earthquake, the stress variation associated with four M > 6 aftershocks was calculated for the period from 2010 to 2017. The results show that (1) the spatial distribution of coseismic stress change is correlated with the rupture pattern of large events and has a fundamental impact on triggering subsequent earthquakes and (2) postseismic viscoelastic relaxation leads to increased Coulomb stress accumulation at the northern and southern edges of the seismogenic Longmenshan fault, which results in enhanced fault instability and the potential for future large events. [ABSTRACT FROM AUTHOR]

On 28 June 2012, a large debris flow occurred in Aizi gully, Ningnan County, Sichuan Province, China. It was the most significant debris flow disaster at a construction site in 2012 in China, which left 40 people dead or missing. Field investigations and model calculations were conducted following the event in order to determine dynamic parameters and execute engineering mitigation measures. Analyzing the collected data, it is found that earthquake and drought play a dominant role in debris flow initiation, and from 1 January 1986 to 31 December 2010, 43 earthquakes with a magnitude greater than 3.0 occurred around the study area. Through calculation it was found that the inducive radius of 16 earthquakes was larger than the distance between the epicenter and the study area, and it proves that the study area is frequently affected by seismic activities. Furthermore, on the basis of calculation of rainfall anomaly index H from January 2011 to June 2012, it can be seen that the rainfall of 2011 is extremely low. The percentage of the rainfall anomaly index is almost less than −34%, which indicates that the drought in the basin is serious. Under the influences of repeated seismic activities and continuous droughts, the structure of soil was destroyed and its strength and permeability changed significantly, providing favorable conditions for debris flow initiation. On 28 June 2012, heavy rainfall with the intensity of 23.3 mm/h occurred, and the total amount of precipitation reached 66.1 mm before 6am of 28 June 2012. Debris flow was induced due to the triggering effect of the torrential rain. Studying the causes of the large-scale debris flows in construction sites can significantly facilitate the prevention and mitigation of future debris flow disasters, as well as reduce the potential of hazards caused by debris flows in major engineering areas. [ABSTRACT FROM AUTHOR]

This paper considers a simplified single-phase depth-averaged model for simulating rock-ice avalanche movement, which incorporates an energy conservation equation to describe the evolution of mass temperature, accounting for the transition from negative to positive values and vice versa. Additionally, this model introduces a saturation parameter that quantifies the impact of pore water pressure on the normal stress of flow materials. To validate the feasibility of the presented model, two laboratory experiments are simulated. Based on the comparison between numerical results and measured data, this study demonstrates that the presented model captures the transformation of rock-ice avalanches from granular flow to debris flow induced by ice melting during movement and the evolution of associated variables including ice volume fraction and temperature. This study further investigates the impact of factors such as fluid viscosity and melting water on rock-ice avalanche movement through simulation. The findings demonstrate that fluid viscosity has an impact on the morphology of rock-ice avalanches and the rate of ice melting. Consequently, this influence directly affects the movement of rock-ice avalanches. In addition, the cohesive force generated by meltwater impedes the progression of low-speed rock-ice avalanches, particularly those with lower water content. • A depth-averaged single-phase rock-ice avalanche model that considers ice melting and temperature evolution is proposed. • A parameter is introduced to quantify the impact of ice melting on the pore water pressure of flow materials. • Fluid viscosity influences the rate of ice melting, thereby affecting the movement of rock-ice avalanche. • Water cohesive forces hinder the movement of low-speed rock-ice avalanches characterized by lower water content. [ABSTRACT FROM AUTHOR]

Natural disasters occur when environmental systems have a disruptive effect on the socio-economic system. In recent years, particular unreasonable human behaviours have amplified losses from natural disasters as result of the increasing complexity of human systems. Because of the lack of both quantitative calculation of this amplification, and analysis of the root cause of these behaviours, existing risk assessment and management research rarely includes unreasonable human behaviour as a critical factor. This study therefore creates three simulation scenarios, each based on a twenty-first-century catastrophe in China, and calculates the disaster losses that are amplified when such behaviour increases exposure (the 2008 Wenchuan earthquake), vulnerability (the 2014 Ludian earthquake) and hazard (the 2021 Zhengzhou rainstorm) levels. In doing so, it intuitively demonstrates the amplification effect caused by unreasonable human behaviour. The results show that these behaviours amplified disaster losses significantly: increased exposure due to unscientific planning nearly doubled the death toll in the Wenchuan earthquake; high vulnerability caused by the low economic level of residents increased the disaster losses of the Ludian earthquake more than tenfold; and the elevated hazard intensity caused by anthropogenic climate change resulted in a 1.44-times expansion of the area severely affected by the Zhengzhou rainstorm. These behaviours have become an important cause of disasters, and the main driving factors behind them—such as neglecting disaster risk; the inability to cope with disasters; and a lack of certainty about how to deal with extreme events—are the inevitable outcomes of societal development. On this basis, we constructed an extended risk framework that included unreasonable behavioural factors and a disaster mechanism, to analyse in depth the relationship between human behaviours and disaster risk prevention in different developmental stages. The results provide an important reference for the development of risk management policies to control these unreasonable behaviours. [ABSTRACT FROM AUTHOR]

Arias intensity is an essential ground motion measure correlating with the potential for earthquake-induced landslides. The Sichuan–Yunnan region, which is primarily mountainous, is a high incidence region of earthquake-induced landslides in China. However, there is no available attenuation relationship for this intensity measure due to the backward construction of the stations. In this study, we developed a region-specific Arias intensity attenuation relationship using the China Strong-Motion Networks Center (CSMNC) database which was established in 2008. We recommend this relationship be applied in the Sichuan–Yunnan region for moment magnitudes ranging between 4.2 and 7.0, distances ranging between 0 and 300 km and with Vs30 (the average shear-wave velocity in the upper 30 m of a soil profile) ranging between 128 and 760 m/s. The current study finds that this relationship's intra-event, inter-event, and total standard deviations are greater than for other regions. This is likely caused by the complicated seismotectonic activities, nonlinear site effects, error from inferring Vs30, basin effects, etc. However, this relationship has the best performance in fitting and predicting the data from the Sichuan–Yunnan region. [ABSTRACT FROM AUTHOR]

A strong earthquake-induced hazard has obvious long-term and spatial heterogeneity, which will result in continuous social and economic losses. Measuring the socioeconomic development level of the disaster area is of great significance for long-term development reconstruction after an earthquake. First, the kernel density estimation (KDE) is used to analyze the spatial effects of 10 extremely earthquake-stricken areas of the Wenchuan earthquake in this paper. Second, the economic gravity centers from 2006 to 2016 are calculated, and the temporal and spatial variation characteristics of the socioeconomic development level of the study area are analyzed. Finally, the relationship between the effects of strong earthquake-induced hazards and the level of socioeconomic development in earthquake-stricken areas is discussed. The results indicate that the effect of landslide hazards show an oscillatory attenuation trend with time from 2008 to 2016 and has significant spatial differentiation characteristics. The economic gravity centers move in the direction of "moving northeast first and moving southwest later" with time, and the movement trend is closely related to the effect of hazard and the industrial structure of the earthquake-stricken areas. [ABSTRACT FROM AUTHOR]

Climate change affects the species spatio‐temporal distribution deeply. However, how climate affects the spatio‐temporal distribution pattern of related species on the large scale remains largely unclear. Here, we selected two closely related species in Taxus genus Taxus chinensis and Taxus mairei to explore their distribution pattern. Four environmental variables were employed to simulate the distribution patterns using the optimized Maxent model. The results showed that the highly suitable area of T. chinensis and T. mairei in current period was 1.616 × 105 km2 and 3.093 × 105 km2, respectively. The distribution area of T. chinensis was smaller than that of T. mairei in different periods. Comparison of different periods shown that the distribution area of the two species was almost in stasis from LIG to the future periods. Temperature and precipitation were the main climate factors that determined the potential distribution of the two species. The centroids of T. chinensis and T. mairei were in Sichuan and Hunan provinces in current period, respectively. In the future, the centroid migration direction of the two species would shift towards northeast. Our results revealed that the average elevation distribution of T. chinensis was higher than that of T. mairei. This study sheds new insights into the habitat preference and limiting environment factors of the two related species and provides a valuable reference for the conservation of these two threatened species. [ABSTRACT FROM AUTHOR]

We present an offline paleo-data assimilation methodology that formally combines the analog assimilation method (AA) and the Kalman filter (KF), utilizing the KF as a postprocessor of the AA output. This methodology can be applied to reconstruct climate fields that are spatially separated from proxy-based reconstructions by using the spatial covariability generated by a climate model. Our method is applied to a set of spatially resolved and spatially consistent climate reconstructions of several variables reflecting different seasons, incorporating the application of methodological variants that have undergone rigorous testing in terms of both improving statistical methodology and physical interpretation. This contrasts with applications primarily based on transfer relationships of annual means of local, single variable or bivariate, climate model priors into paleo proxy states. The gains from adding the KF postprocessor are modest in our test case of reconstructing sea level pressure (SLP) geopotential height fields in the northeast Pacific, utilizing paleoclimatic temperature and moisture reconstructions in western North America. Notably, SLP reconstruction skill is enhanced in the oceanic region south of Alaska that is strongly associated with wet winters in western North America. The results suggest that the AA method is approaching optimality in this test case, driven by the quality of the paleoreconstruction information used to drive the AA process, along with the realism of the climate model employed, to which the KF postprocessing step is added. The derived reconstructions are then used for evaluation of the relationship between winter SLP and precipitation in California over the past ∼450 years. [ABSTRACT FROM AUTHOR]

The Mabian fault zone, distanced ∼200 km to the east of the Xianshuihe–Xiaojiang fault system, is located in the western vicinity of the relatively stable South China Block. Since 1917, about 54  M > 4.7 earthquakes, including the 1974 M s = 7.1 Mabian event have occurred around this fault zone, suggesting that significant strain is localized within the Mabian fault zone. Here, we built a 3-D finite element model to investigate the main parameters that possibly control strain localization around the Mabian fault zone averaged over the active deformation timescale. In the model, the Xianshuihe–Xiaojiang fault system is specified as a discontinuous contact interface for its motion governed by a Coulomb-friction law, and the crustal rheology is simplified as a frictional upper crust underlain by a viscoelastic lower crust. In addition, global positioning system (GPS) data are used to mimic the horizontal tectonic loading, and the model base is supported by a hydrostatic pressure. Numerical results show that with the weak fault strength and the low viscosity contrast between the Tibetan plateau and the South China Block, strain rates from motion of the southeastern Tibetan plateau could be propagated across the Xianshuihe–Xiaojiang fault system more widely within the Mabian fault zone. Constrained by the estimates on slip rates of the faults and on rheological structures of the crust, our optimal model predicts the effective friction coefficient of the Xianshuihe–Xiaojiang fault of 0.05–0.1. Under this condition, relative motion across the Xianshuihe–Xiaojiang fault system is largely partitioned by the geometric bend near the central portion of the fault system, resulting in a relatively high strain rate of 2.1–3×10–8 yr–1 accumulating around the Mabian fault zone. Keeping the weak strength of the fault, numerical results also show that if the central portion of the Xianshuihe–Xiaojiang fault system follows the Daliangshan fault, strain accumulation around the Mabian fault zone could be significantly reduced. It thus can be concluded that the strain partitioning from the weak strength and the special geometry of the Xianshuihe–Xiaojiang fault system must play a crucial role in active deformation around the Mabian area out of the Tibetan plateau deformation domain. This in turn means that in the Xianshuihe–Xiaojiang fault system, the Anninghe–Zemuhe fault is still the main boundary between the southeastern Tibetan plateau and the South China Block. [ABSTRACT FROM AUTHOR]

Cohesion is the main inter-controlled factor for the stability of fine-grained sediments in debris flow, and plays an important role in debris flow hazard early warning. At present, there is no cohesion rapid remote sensing detection model, which seriously affects the development of quantitative evaluation on debris flow stability. How to use remote sensing to quickly detect the cohesion of fine-grained debris has become an important scientific issue. Therefore, strengthening the research on the cohesion hyperspectral detection model, indicating its sensitive spectral bands, and establishing a quantitative model between cohesion and these bands are of great significance not only in discovering the stability mechanism, but also in quickly establishing the stability detection model for gully sediments. Taking the Beichuan debris flow as the study area, we carried out experiments on cohesion, cohesion influencing factors, and spectra. Firstly, six cohesion hyperspectral sensitive bands are indicated in red, near infrared portions of the electromagnetic spectrum, including 750, 1578, 1835, 2301, 2305, and 2309 nm; secondly, these bands discover the cohesion influencing factors. Band 750 nm indicates the characteristics of cohesion, effective internal friction angle, and permeability coefficient, while the other five bands indicate the characteristics of effective internal friction angle, density, and moisture; finally, a hyperspectral remote sensing detection model for the fine-grained sediments cohesion is established. With a correlation coefficient of 0.56, and p value less than 0.001, the model indicates that cohesion has a great significant correlation with the six bands. This not only provides sensitive bands for detecting cohesion of fine-grained sediments using remote sensing, but also provides a scientific basis for rapid detection of the fine-grained sediments' stability in large areas. [ABSTRACT FROM AUTHOR]

Extensive landslides were triggered by the Wenchuan earthquake (in China) on 12 May 2008, causing a tremendous amount of loose material suspended on the hillslopes, likely to be eroded and transported by rain. It is of great significance to study the long-term variation of the quantity and spatiotemporal distribution of loose deposits after a great earthquake in order to understand the restoration process, to assess the risk of future soil erosion, including geological hazards, and to further develop ecological governance strategy. In this study, information about the multi-temporal loose deposits on the ranges of the Baisha River Basin, an alpine valley near the epicenter, was extracted by object-oriented remote sensing interpretation, and analysis on their spatiotemporal variation showed that the earthquake in 2008 resulted in loose deposits covering an additional area of 81.09 km2, with a volume estimated at 0.357 billion m3. Within five years after the earthquake, the vegetation had recovered rapidly, and the extent of the deposits was significantly less. From 5 to 13 years after the earthquake, the vegetation continued to recover but at a slower rate and a decreasing trend in newly formed deposits was evident. The total area, volume and quantity of the loose deposits gradually stabilized. The geometric mean center of the loose deposits gradually moved back towards the upstream area after the earthquake and, by 2021, the mean center was about 4 km away from its pre-earthquake position. Taking the mean center of the loose deposits in 2008 as the center, the deposits in the downstream area shrank significantly after the earthquake, but collapses and landslides of deposits persisted in the upstream area to the west-southwest, west-northwest and north-northwest from the mean center, indicating future source areas of new loose deposits in the basin. [ABSTRACT FROM AUTHOR]

The impact and feedback of climate--vegetation interaction on the potential habitat of plants is one of the focuses of terrestrial ecosystem and global climate change research. Based on 246 occurrence records of S. chamaejasme and 28 environmental variables (climate, topography and soil), we predicted and analyzed the suitable habitat distributions and shifts of S. chamaejasme under current and future (by 2050 and 2070) climate scenarios using the maximum entropy (Maxent) model. The Area Under the receiver operating characteristics Curve (AUC) was used to evaluate the model performance. The key environmental factors were screened by Jackknife tests. The results showed the following: 1) AUC values indicated better performance of MaxEnt modeling. 2) Altitude, annual precipitation, extreme moisture conditions (including precipitation of the wettest and the driest month) and mean temperature of the coldest quarter were the most predominant environmental factors influencing S. chamaejasme's habitat suitability. 3) In the current scenario, S. chamaejasme distributed in Qinghai--Tibet plateau, Loess Plateau, Inner Mongolia plateau and Yungui plateau (covering 44.16% of total land of China), especially in Sichuan (37.25%) and Gansu (34.65%) province. 4) With climate change, an increasing trend for the distribution (except in 2050_RCP2.6 and 2050_RCP8.5) had taken place in the area of all suitable classes comparing current and future scenarios overall, while the trends of variation are insignificant. At the same time, the centroid of highly suitable distribution regions shifted to northeast China, and the distribution regions moderately extended to the south. This paper may provide a deep insight for further research and practice management on S. chamaejasme. [ABSTRACT FROM AUTHOR]

On January 8, 2022, the MS 6.9 Menyuan earthquake occurred in Menyuan, Qinghai province, China; the epicenter was on the fault terrace of the Lenglongling and Tuolaishan faults. To investigate the coseismic and pre-seismic deformation associated with the event, we constructed physical models using interferometric synthetic aperture radar (InSAR) and global navigation satellite system (GNSS) data and inverted the fault slip distribution, fault coupling fraction, fault slip deficit and strain rate. The primary inversion results were as follows: (1) The InSAR coseismic deformation pattern indicates that the left-lateral strike-slip deformation occurred in the NW–SE direction, with the maximum relative displacement in the line-of-sight direction being 1.3 m. (2) The coseismic slip mainly occurred in a 30 × 25 km region at a depth of 0–8 km. The maximum fault slip was 3.81 m with a moment magnitude (MW) of 6.6. (3) Based on the fault coupling inversion, the seismogenic fault was strongly locked (> 0.96) up to a depth of ~ 10 km before the Menyuan earthquake. The coseismic rupture zone in the fault strike direction was significantly smaller than the pre-seismic locked region. (4) The pre-seismic strain rates revealed NE–SW compressive and NW–SE tensile deformations, reflecting a considerable left-lateral strain accumulation in the seismogenic region, with a maximum shear strain rate of 2.6 × 10–8/year. Therefore, attention must be paid to the seismic hazards posed by the Tuolaishan and Lenglongling faults adjacent to the seismogenic region. [ABSTRACT FROM AUTHOR]

Cremastraappendiculata (Orchidaceae) is a perennial medicinal herb, which is included in the national second-class protected plant catalog in China. Due to the influences of climate change and anthropogenic activities, in conjunction with soaring commercial prices, the wild sources of C.appendiculata have been drastically reduced and are in danger of extinction. Consequently, it is important to predict the distribution of potentially suitable growth/propagation areas for C.appendiculata under the backdrop of climate change for its protection and sustainable use. For this study, an optimized maximum entropy model was employed to analyze the distribution patterns and changes of potentially suitable regions for C.appendiculata during different periods since the Last Glacial Maximum (LGM, 18–24 ka). Based on multiple climate change scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), the distribution range of C. appendiculata was predicted for the 2050s (average for 2041–2060), 2070s (average for 2061–2080), and 2090s (average for 2081–2100). The results revealed that during the LGM period, the highly suitable growth area for C.appendiculata was 0.28 × 104 km2, which accounted for only 3.26% of the current highly suitable growth area. During the mid-Holocene (MH, 6 ka) period, the area of highly suitable regions increased to 8.38 × 104 km2, which accounted for 99.30% of the present highly suitable growth area. Further, the cumulative existing potentially suitable growth area for C. appendiculata is 213.9 × 104 km2, which accounts for 22.28% of China's territory. Of these lands, the low, medium, and high suitable areas are 147.76 × 104 km2, 57.71 × 104 km2, and 8.44 × 104 km2, respectively. The highly suitable areas are primarily distributed across Sichuan, Gansu, Shaanxi, Chongqing, Guizhou, Hubei, and Anhui Provinces. Moreover, in the future the potentially suitable growth areas for C. appendiculata will decrease to varying degrees. Further, the results of this study found that the relatively low impact areas for C. appendiculata were mainly distributed across Shaanxi, Sichuan, Chongqing, and Guizhou Provinces. Centroid transfer analysis indicated that the center of potentially suitable growth areas for C.appendiculata shifted to the northwest in SSP2-4.5 and SSP3-7.0, while they initially shifted to the northwest and then to the southeast in SSP1-2.6 and SSP5-8.5. [ABSTRACT FROM AUTHOR]

We provide two datasets for tracking the debris flow induced by the 2008 Wenchuan Mw 7.9 earthquake on a section of the Longmen mountains on the eastern side of the Tibetan plateau (Sichuan, China). The database was obtained through a literature review and field survey reports in the epicenter area, combined with high-resolution remote sensing image and extensive data collection and processing. The first dataset covers an area of 892 km2, including debris flows from 2008 to 2020 (an updated version). 186 debris flows affecting 79 watersheds were identified. 89 rainfall stations were collected to determine the rainfall events for the post-earthquake debris flow outbreak. The second database is a list of mitigation measures for post-earthquake debris flows, including catchment name, check dam number, coordinates, construction time, and successful mitigation date. The datasets can aid different applications, including the early warning and engineering prevention of post-earthquake debris flow, as well as provide valuable data support for research in related disciplines. Measurement(s) debris flow • water-based rainfall • check dam Technology Type(s) satellite imaging • weather station Sample Characteristic - Organism earthquake induced debris flows and mitigation measures Sample Characteristic - Environment earthquake Sample Characteristic - Location Wenchuan County [ABSTRACT FROM AUTHOR]

It is widely recognized that post-seismic mass movements amplify and decay. Previous studies have found that most post-seismic mass movement is concentrated in the first few years following an earthquake. A major debris flow occurred in Wenchuan County in 2019, 11 years after the 2008 Wenchuan earthquake, showing that there might be a different temporal evolution pattern. In Wenchuan Country, the area struck by the 2019 disaster was investigated to explore whether a pattern existed. Remote sensing and field surveys investigate the initiation processes, sediment supply, and triggering rainfall. The result shows that most of the active landslides occurred in high-elevation areas where vegetation cover was lacking, and nearly half of them were reactivated landslides. The debris flows were mainly initiated by run-off erosion of debris in steep channels, and more than half of the sediment supply was from deposition along the channels in some catchments. The spatial and temporal evolution of debris flows was analyzed by combining our investigation results with historical events. More debris flows occurred in the northern part of the study area, where the relative annual rainfall and coseismic landslide density were low. The average values of debris-active catchments' size and relief are increasing, while the average values of their coseismic landslide density and the annual rainfall received were decreasing from 2008 to 2019. Larger catchments receiving less annual rainfall tend to have a more prolonged and enhanced mass movement. [ABSTRACT FROM AUTHOR]

The Xuebaoding W–Sn–Be mining area, located in the Songpan–Garze orogenic belt in western China, is known for producing large, colorful, euhedral crystals of scheelite, cassiterite, and tabular beryl. Zircon LA-ICP-MS U–Pb dating of the Wuzhutang granite yields a concordia age of 218.96 ± 2.1 Ma, and a weighted mean 206Pb/238U age of 218.98 ± 1.12 Ma. Cassiterite LA-MC-ICPMS dating of the quartz vein bearing beryl, cassiterite, and scheelite, yields a concordant age of 213.5 ± 1.7 Ma. These observations indicate that magmatic activities and mineralization on the western side of the Zibaishan dome occurred during the late Indosinian, prior to their occurrence on the eastern side of the dome, reflecting the fact that the granite may have undergone two epochs of magmatic evolution and metallogenic processes. Geochemical analysis revealed that the Wuzhutang granite has relatively high A/CNK (average: 1.05) and differentiation index (DI; 81.16~85.88) values, and that they are enriched in W, Sn, Be, Li, and Cs. Unlike the Pukouling and Pankou granites, the Wuzhutang granite contains a certain amount of plagioclase and relatively high contents of Ba (633~1007 ppm) and Sr (334~411 ppm). Sr–Nd–Pb isotope values (87Sr/86Sr(t) = 0.70747–0.70865, εNd(t) = −6.35 to –4.34, 206Pb/204Pb = 18.186–18.3, 207Pb/204Pb = 15.556–15.592, and 208Pb/204Pb = 38.268–38.432) indicate a Mesoproterozoic basement origin for the Wuzhutang granite. We suggest the three granites belong to a peraluminous magma system and were derived by partial melting of the upper crust, the magma of the Wuzhutang granite originated from a deeper source and exhibits a lower degree of differentiation than that of the Pankou and Pukouling granites. [ABSTRACT FROM AUTHOR]

This paper summarizes a sophisticated field investigation of the seismic damage to a continuous rigid frame bridge. Cracking and deformation of main girder, failure of bearings, and damage of piers were examined. The whiplash effect of the long side span of main bridge caused the prominent damage of bearings and restrainers on the transition piers. A numerical model was developed for supplementary analysis. The multi-directional dynamic analyses were conducted, which revealed a satisfactory agreement with the field investigation. Based on the numerical model, the effect of anti-tensile configurations was analyzed for reducing the whiplash effect of the side span. [ABSTRACT FROM AUTHOR]

【Objective】 The present paper aimed to study the spatial and temporal distribution characteristics of low-temperature continuous rain disasters in rice during the heaving-heading stage in Sichuan province, in order to provide scientific basis for disaster prevention and reduction of low-temperature continuous rain disasters in rice at different growth stages in Sichuan province. 【Method】 According to the topographic and geomorphic types of Sichuan province, the rice planting regions were divided into six regions, namely, the marginal mountain region around the basin, the parallel range-valley region in the east of the basin, the hilly region in the south of the basin, the shallow hilly region in the middle of the basin, the flat hill region in the west of the basin and the mountainous region in the southwest of Sichuan. Based on the data of daily mean temperature, maximum temperature, minimum temperature, precipitation and sunshine duration of 21 agricultural meteorological stations in Sichuan province from 1961 to 2020, the spatial and temporal distribution characteristics of low-temperature continuous rain during the period of rice starting from heading to heading were analyzed by using statistical analysis method combined with evaluation indexes of low-temperature continuous rain. 【Result】 (i) The frequency of mild, moderate and severe cold damage of rice during booting and heading stage in Sichuan province was as follows: 0%-32.5%, 0%-44.8% and 0%-50.3%, and the large values were all in the southwest Mountain area of Sichuan. Although the occurrence frequency of mild and moderate cold damage was relatively low, the distribution area of mild cold damage was the widest, followed by moderate cold damage, and the distribution area of severe cold damage was the smallest, only in the southwest Mountain area of Sichuan. (ii) The frequency of mild, moderate and severe continuous rain disasters were 0.4%-3.8%, 0%-5.2% and 0%-0.5%, respectively. (iii) The frequency of low-temperature continuous rain disasters was 0%-9.1% from 1961 to 2020, 0%-9.1% from 1991 to 2000, and 0%-3.3% from 1961 to 1970. (iv) From 1961 to 2020, the frequency of low temperature cold damage and low temperature continuous rain disaster passed the significance test of 0.05 over time, showing a decreasing trend. The frequency of continuous rain disaster did not change significantly with time and did not pass the morphological significance test of 0.05. 【Conclusion】 The frequency of low-temperature continuous rain disaster was high in the mountainous area of southwest Sichuan. In Sichuan province, the continuous low temperature rain disaster of rice during booting and heading stage showed a decreasing trend in recent years, which was consistent with the results of the reduction of low temperature cold damage and continuous rain disaster under the background of climate warming. [ABSTRACT FROM AUTHOR]

To combat the coronavirus epidemic, the city at the epicentre, Wuhan, China, was placed under strict lockdown in 2020 for 76 days. Unlike past emergency response situations in China, government-organised Residents' Committees (RC), property management companies, and other community institutions played an unusually prominent role in enforcing the lockdown, providing essential services, and maintaining public order. This article explains the role of community institutions in emergency management in China through case studies of the 2008 earthquake in Chengdu, the 2016 flood in Wuhan, and later, the 2020 coronavirus outbreak. Drawing on databases of media reports and individual accounts, I argue that the administrative and coercive power of community institutions stems from their spatiality—from being embedded in gated residential communities, maintaining contact and familiarity with residents, and having control over physical structures. During earthquakes and floods, when the physical space that give community institutions power is changed and destroyed, the role of these organisations in emergency response diminishes. However, when facing an epidemic, in which structured physical space is not only unchanged but also reinforced, community institutions take the lead. [ABSTRACT FROM AUTHOR]

Highlights: The topography and climate background determine that the hazard happens periodically, and these factors are fundamental for the weak vulnerability in the Sedongpu basin; The dynamic glacier simulations with the Elmer/Ice model showed that the glacier surface velocity can reach 19 cm/d on the Dongpu glacier; Heavy rain and an earthquake were triggering factors of the ice avalanche that led to the glacial debris flow. In this paper, the glacial debris flow blockage event, on 17 October 2018, in the Sedongpu basin of the Yarlung Zangbo River is taken as an example to analyse the occurrence and development of glacier hazards in this region. Multi-sources including remote sensing products, DEM, earthquake records and meteorological data were used to analyse the characteristics and mechanism of glacier hazards. The Elmer/Ice dynamic model was chosen to simulate the glacial surface velocity. It was found that topography and climate background determine that the hazard happens periodically. Based on the meteorological records of the Linzhi station, the warming rate was greater than 0.40 °C/10a during the period 1960–2017. The short-term heavy rainfall with daily values of 9.3 mm before the blockage event was also regarded as a factor. Both heavy rain and earthquake were triggering factors of the ice avalanche that led to the glacial debris flow. The glacier surface velocity of the Dongpu glacier simulated by Elmer/Ice model can reach 19 cm/d. This study has extensive applicability significance in glacier hazard mitigation under a changing climate. [ABSTRACT FROM AUTHOR]

Extremely hard-hit areas face frequent secondary geological hazards and difficulties in vegetation recovery, and subsequent effects have a significant impact on land cover changes. At present, there is a lack of research on the dynamic restoration of, and changes in, the ecological environment before and after an earthquake, and especially a lack of quantitative assessment of the impact of earthquakes on land cover at the microscopic scale of spatial distribution of landscape indices. Taking the Lushan earthquake in Sichuan Province as an example, this paper obtained land cover data from the study area between 2012 and 2020, and analyzes the spatial distribution characteristics and influencing factors of land cover change frequency by using a comprehensive land cover degree index, land cover transfer matrix and landscape ecology index. The results show that the types of cropland, forest, built-up and bare land have changed significantly in the study area. During the earthquake recovery period, the comprehensive land cover index of the study area showed an increasing trend, and land cover has been continuously improved under the effect of artificial measures and natural restoration. After 2013, patch density (PD) and landscape shape index (LSI) values decreased and aggregation index (AI) values increased for the vast majority of landscape land classes, indicating a benign ecological development across the region in the post-earthquake period. The research results are not only helpful to establish scientific ecological environmental management in the earthquake-stricken areas, but also helpful to formulate medium- and long-term ecological environmental monitoring and ecological restoration plans based on land cover change patterns. [ABSTRACT FROM AUTHOR]

Tidal stresses could load or unload focal media and trigger small to moderate earthquakes in and around the focal region before a large or great earthquake. Based on the preliminary reference Earth model, we calculated the time series of tidal Coulomb failure stress (TCFS) acting on the focal fault plane of the Wenchuan earthquake. For earthquakes (2.5≤ML≤4.0) that occurred in and around the focal region from January 1990 to April 2008, we calculated the time rate of TCFS, Δ TCFS, at the occurrence time of each earthquake. These earthquakes were divided into two categories on the basis of the signs of Δ TCFS: one is positive earthquakes (PEQs) occurring at times of Δ TCFS > 0 and the other negative earthquakes (NEQs) occurring at times of Δ TCFS < 0. First, we obtained cumulative seismic strain release (CSSR) curves of NEQs and PEQs and found that the two curves nearly overlapped prior to September 2004 and then began to separate increasingly with time. We used a parameter Rp , the proportion of seismic strain release of PEQs, to investigate the effect of TCFS on earthquake occurrence and found that Rp was significantly higher than 0.5 about 6 months before the Wenchuan event at a 99 % confidence level, indicating a significant correlation between earthquake occurrence and increasing TCFS. Furthermore, we calculated the slope k (time rate) of the CSSR curve vs. time for PEQs and NEQs separately. It was observed in the pre-event period that the seismic strain release accelerated when TCFS increased but decelerated when TCFS decreased. The difference in the time rate of seismic strain release between PEQs and NEQs was quantified using Rk , the ratio of k for PEQs to that for NEQs. We discovered stable Rk values (around 1.0) until they began to rise rapidly with time in early 2005, reaching their highest value of 2.7 just before the Wenchuan event. Rk could reveal the promoting and inhibiting effects of tidal stress on seismic strain release. When kp increases alone or kn decreases alone, Rk will increase. Thus, an increase in Rk corresponds to a promoting effect during times of increasing TCFS and an inhibiting one during that of decreasing TCFS. Both effects were observed in the focal region prior to the Wenchuan mainshock. The b value in the Gutenberg–Richter relationship decreases as the tectonic stress in the crust increases. We also calculated the temporal evolution of the b value in the study region. It was observed that after 2.5 years of increasing tectonic stress, the focal region became unstable, and the tidal stress began to take effect. The effects of the tidal stress were gradually enhanced as the tectonic stress increased further. The increase in the tidal Coulomb failure stress may have aided the occurrence of earthquakes, whereas the decrease had the opposite effect. This observation may shed light on the seismogenic processes that led to the Wenchuan earthquake and its precursors. [ABSTRACT FROM AUTHOR]

To support the implementation of China's carbon neutrality target, this study assesses the impact of future climate change on hydroelectricity production (HP) in China. We developed a hydropower database for mainland China, which covers 92% of the installed capacity indicated by national statistics (352 GW in 2018). An HP model was applied to simulate monthly HP by 3,521 conventional plants at different levels of global warming (1°, 1.5°, 2°, and 3°C above preindustrial) using an ensemble of monthly streamflow time series computed by five global hydrological models (GHMs), where each global hydrological model was driven by four global climate models (GCMs). With a probability of 80%, limiting global warming to 1.5°C will constrain changes of national HP to the range of −1.4%–2.5% as compared to near‐present climate (1°C). In case of a 3°C world, this range more than doubles. HP is projected to likely increase in the two provinces Sichuan and Yunnan that encompass more than half of China's installed capacity. However, with a probability of about 10%, HP may decrease in a 3°C world by more than 15% in five provinces, and 40% of the installed capacity may suffer from an HP decrease of more than 5%. The uncertainty of projected HP changes is mainly due to the GCMs. We found that relative changes in annual HP and streamflow often differ in magnitude and direction as HP depends on seasonal streamflow patterns and installed capacities that determine the maximum flow through the turbines. Key Points: A new hydropower database for mainland China was compliedSignificant reductions due to climate change cannot be precluded for 40% of the installed capacityChanges in annual hydroelectricity production and streamflow often differ in magnitude and direction [ABSTRACT FROM AUTHOR]

In arid regions, debris flows are occasionally observed when torrential rainfall hits steep slopes with unconsolidated materials. Despite the important related hazards, not much is yet known about the critical rainfall conditions for debris flow initiation in dryland areas. In this study, we use high-resolution digital surface models and weather radar rainfall estimates for the detection and characterization of triggering and non-triggering storms. We focus on the arid slopes of the Dead Sea north- western margins and use the differences of digital surface models to identify deposits from over 40, relatively small, shortlived debris flows (SLDFs) occurred between 2013 and 2019. We divide them into four groups based on their spatial distribution and triggering period, and identify the most likely triggering storm for each group. Using high-resolution weather radar data we show that the SLDFs were likely initiated by an intense convective cell (lasting 20 to 45 min) which was preceded by significant rainfall amounts (8-12 mm) delivered during the storm. Comparing triggering and non-triggering storms, we observed that rain intensity alone is insufficient to explain the phenomena, and discuss the possibility that antecedent rainfall could represent a critical factor for the triggering of SLDFs in steep slopes of arid environments. [ABSTRACT FROM AUTHOR]

This study investigates the autumn precipitation in Sichuan Basin (SB), China in combination with reanalysis data sets of aerosol and meteorological fields from 2008 to 2018. To identify the aerosol impacts on precipitation, we carefully selected and divided the data into multiple groups according to vorticity, precipitation amount category, aerosol pollution level, and the geopotential height (GH) in the upper troposphere. Our data show that the precipitation in SB are generally reduced and weakened in afternoon to evening, but enhanced and intensified after midnight under the aerosol polluted condition. By analyzing data contrasts between different groups, we find that aerosol pollution in SB reduces shortwave heating near surface, which enhances the tropospheric stability and inhibits the vertical motion and rainfall in the afternoon to early evening. As the stability reduces within the basin, the vertical motions are invigorated to enhance and intensify the rain after midnight. Therefore, we conclude that the aerosol pollution in SB and the rapid adjustment of aerosol‐radiation interaction amplify the diurnal features of precipitation in autumn. Plain Language Summary: The present study illustrates that aerosols modify atmospheric thermodynamic states by direct effects and further impact diurnal variation of precipitation over the Sichuan Basin (SB). Key Points: Precipitation in Sichuan Basin are reduced and weakened in the afternoon and evening but enhanced and intensified after midnightAerosol pollution reduces shortwave heating at the surface, enhances tropospheric stability, and inhibits vertical motion in the afternoonThe rapid adjustment of aerosol‐radiation interaction amplifies the diurnal evolution of thermodynamic and precipitation features [ABSTRACT FROM AUTHOR]

The 2008 Wenchuan earthquake triggered local geomorphic changes rapidly and gradually and produced abundant materials through external processes. The abundant materials increased the risks of geomorphic hazards (flash floods, landslides, and debris flows) induced by extreme precipitation in the area. To reduce sediment transport present in geomorphic hazards, intervention measures such as dams, levees, and vegetation revetments have been constructed in specified sites. This study concentrated on the assessment of intervention effects incorporated with various facilities on post-earthquake fragile mountains in the short-medium term. Take the Xingping valley as an example, we used the CAESAR-Lisflood landscape evolution model to simulate three different scenarios including unprotected landscapes, present protected landscapes, and enhanced protected landscapes in 20112013. We compared the geomorphic changes and defined two indicators to assess the intervention effects. The results showed that the mitigation facilities were effective, especially engineering measures that cooperated with vegetation revetments in the upstream area, and the present mitigation measures were inadequate to stop materials loss and prevent hazards from the upstream area. Moreover, the effectiveness reduced gradually caused by the storage capacity of dams decreased. The simulation methods assessed the ability and effectiveness of cooperated control measures and could support optimum mitigation strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: Climate change has always been a noticeable factor in the research of species distribution. In recent decades, the habitats of species have been gradually destroyed due to the changing climate. Thus, in order to predict how climate change will influence the survival and suitable habitats of wild Morchella Dill. ex Pers. species in China, we used a maximum entropy model to simulate the changes in its distribution area from historical periods to future periods. Our results illustrate that precipitation, elevation and temperature are indispensable factors affecting the presence and suitable habitats of wild Morchella species. Furthermore, this research showed us a promising trend that, regardless of which scenario, the suitable area of the species will increase to a certain scale in the near future. Based on these findings, we could explore and design an optimal scheme for the conservation of wild Morchella resources. Morchella is a kind of precious edible, medicinal fungi with a series of important effects, including anti-tumor and anti-oxidation effects. Based on the data of 18 environmental variables and the distribution sites of wild Morchella species, this study used a maximum entropy (MaxEnt) model to predict the changes in the geographic distribution of Morchella species in different historical periods (the Last Glacial Maximum (LGM), Mid Holocene (MH), current, 2050s and 2070s). The results revealed that the area under the curve (AUC) values of the receiver operating characteristic curves of different periods were all relatively high (>0.83), indicating that the results of the maximum entropy model are good. Species distribution modeling showed that the major factors influencing the geographical distribution of Morchella species were the precipitation of the driest quarter (Bio17), elevation, the mean temperature of the coldest quarter (Bio11) and the annual mean temperature (Bio1). The simulation of geographic distribution suggested that the current suitable habitat of Morchella was mainly located in Yunnan, Sichuan, Gansu, Shaanxi, Xinjiang Uygur Autonomous Region (XUAR) and other provinces in China. Compared with current times, the suitable area in Northwest and Northeast China decreased in the LGM and MH periods. As for the future periods, the suitable habitats all increased under the different scenarios compared with those in contemporary times, showing a trend of expansion to Northeast and Northwest China. These results could provide a theoretical basis for the protection, rational exploitation and utilization of wild Morchella resources under scenarios of climate change. [ABSTRACT FROM AUTHOR]

The deformation pattern and slip partitioning related to oblique underthrusting of the Tarim Basin in the eastern Tian Shan orogenic belt are not well understood because interior deformation images are lacking. The Baoertu fault is an E-W--striking, ~350-km-long reactivated basement structure within the eastern Tian Shan. In this study, we quantify its late Quaternary activity based on interpretations of detailed highresolution remote sensing images and field investigations. Three field observation sites along an ~80-km-long fault segment indicate that the Baoertu fault is characterized by sinistral thrust faulting. Based on surveying of the displaced geomorphic surfaces with an unmanned drone and dating of the late Quaternary sediments using radiocarbon and optically stimulated luminescence (OSL) methods, we estimate a late Quaternary leftlateral, strike-slip rate of 1.87 ± 0.29 mm/yr and a N--S shortening rate of 0.26 ± 0.04 mm/ yr for this fault. The lithospheric Baoertu fault acts as a decoupling zone and accommodates the left-lateral shearing caused by the oblique underthrusting of the Tarim Basin. In the eastern Tian Shan orogenic belt, the oblique convergence is partitioned into thrust faulting across the entire range and sinistral slip faulting on the high-dip basement structure within the orogen. This active faulting pattern in the eastern Tian Shan of sinistral shearing in the center and thrust faulting on both sides can be viewed as giant, crustal-scale positive flower structures. [ABSTRACT FROM AUTHOR]

In steep wildfire-burned terrains, intense rainfall can produce large runoff that can trigger highly destructive debris flows. However, the ability to accurately characterize and forecast debris flow susceptibility in burned terrains using physics-based tools remains limited. Here, we augment the Weather Research and Forecasting Hydrological modeling system (WRF-Hydro) to simulate both overland and channelized flows and assess postfire debris flow susceptibility over a regional domain. We perform hindcast simulations using high-resolution weather-radar-derived precipitation and reanalysis data to drive non-burned baseline and burn scar sensitivity experiments. Our simulations focus on January 2021 when an atmospheric river triggered numerous debris flows within a wildfire burn scar in Big Sur – one of which destroyed California's famous Highway 1. Compared to the baseline, our burn scar simulation yields dramatic increases in total and peak discharge and shorter lags between rainfall onset and peak discharge, consistent with streamflow observations at nearby US Geological Survey (USGS) streamflow gage sites. For the 404 catchments located in the simulated burn scar area, median catchment-area-normalized peak discharge increases by ∼ 450 % compared to the baseline. Catchments with anomalously high catchment-area-normalized peak discharge correspond well with post-event field-based and remotely sensed debris flow observations. We suggest that our regional postfire debris flow susceptibility analysis demonstrates WRF-Hydro as a compelling new physics-based tool whose utility could be further extended via coupling to sediment erosion and transport models and/or ensemble-based operational weather forecasts. Given the high-fidelity performance of our augmented version of WRF-Hydro, as well as its potential usage in probabilistic hazard forecasts, we argue for its continued development and application in postfire hydrologic and natural hazard assessments. [ABSTRACT FROM AUTHOR]

Rainfall is the main factor that induces debris flow. Satellite rainfall products provide a new source of data in terms of debris flow-triggering conditions to overcome the lack of rainfall data coverage from ground-based rainfall gauges in large-scale mountainous regions. In this study, the applicability of four satellite rainfall products (CMORPH, GPM, MSWEP, and PERSIANN) in the Hengduan Mountain region (HMR) was evaluated with reference to ground observation data from 2000 to 2020. The critical rainfall and rainfall thresholds under different rainfall patterns and warning levels that trigger debris flows were analyzed according to the empirical cumulative distribution function (ECDF) and cumulative probability. The results showed that CMORPH (comprehensive indicator score (CI = 0.72) and GPM (CI = 0.70) performed better in the simulation of daily rainfall sequence consistency and extreme rainfall conditions in the study area. CMORPH also had the highest reconstruction rate for correctly capturing rainfall events that triggered debris flows, with a value of 89%. Approximately half of the rainfall patterns that cause debris flows are antecedent-effective-rainfall-dominated. Both intraday-rainfall-dominated and intraday-antecedent-rainfall-balanced patterns were below 30%. There were evident differences in the critical rainfall for different rainfall patterns under the same warning level. By comparing the results of previous studies on rainfall thresholds, it is believed that the results of this study confirm the application of satellite rainfall products; in addition, the calculated rainfall thresholds can provide a reference for the early warning of debris flows in the HMR. In general, this work is of great significance to the prediction and early warning of debris flow hazards. [ABSTRACT FROM AUTHOR]