Across a gradient belt of the Western Sichuan Plateau,geohazards have seriously limited economic and social development.According to incomplete statistics,15,673 geohazards have been recorded in the study area.In orde...Across a gradient belt of the Western Sichuan Plateau,geohazards have seriously limited economic and social development.According to incomplete statistics,15,673 geohazards have been recorded in the study area.In order to mitigate the threat of geohazards to human engineering activities in the region,an overall understanding of the distribution pattern of geohazards and susceptibility assessment are necessary.In this paper,a gradient belt of the Western Sichuan Plateau and its zoning criteria were defined.Subsequently,on the basis of relief amplitude,distance to faults,rainfall,and human activities,three indicators of endogenic process were introduced:Bouguer gravity anomaly gradient,vertical deformation gradient,and horizontal deformation gradient.Thereafter,the distribution patterns of geohazards were investigated through mathematical statistics and ArcGIS software.By randomly selecting 10,449 hazards,a geohazard susceptibility map was generated using the Information Value(IV)model.Finally,the IV model was validated against 5224 hazards using the Area Under Curve(AUC)method.The results show that 47.6%of the geohazards were distributed in the zone of steep slope.Geohazards showed strong responses to distance to faults,human activities,and annual rainfall.The distribution of geohazards in the gradient belt of the Western Sichuan Plateau is more sensitive to vertical internal dynamics factors(such as vertical deformation gradient and Bouguer gravity anomaly gradient)without any apparent sensitivity to horizontal internal dynamics factors.The areas of high and very-high risk account for up to 32.22%,mainly distributed in the Longmenshan and Anning River faults.According to the AUC plot,the success rate of the IV model for generating the susceptibility map is 76%.This susceptibility map and geohazard distribution pattern can provide a reference for geological disaster monitoring,preparation of post-disaster emergency measures,and town planning.展开更多
Geohazards along highways are the main natural hazards that could affect the safety and operation of highway systems.Understanding the risks faced by highways in areas affected by geohazards is an urgent problem to be...Geohazards along highways are the main natural hazards that could affect the safety and operation of highway systems.Understanding the risks faced by highways in areas affected by geohazards is an urgent problem to be solved.This study used historical geohazard events from Sichuan Province and highway network data to propose a geohazard risk index that reflects the risk geohazards along highways.Furthermore,this work applied the entropy method and expert scoring to calculate the weight of the index.The spatial distributions of landslides,debris flows,collapses,and unstable slopes along the highways were analysed based on ArcGIS spatial statistics,and the highway geohazard intensity index were obtained.The relationships between slope,rainfall,vegetation coverage,rock type,land use,and incision depth with geohazards were analysed,and the highway geohazard susceptibility index was calculated by the weighted information method.Based on the intensity and susceptibility index,we obtained a geohazard risk index which can better evaluate the risk of highways,and made a highway geohazard risk map to aid the prevention and mitigation of geohazards along highways and assist with highway network planning.展开更多
In order to prevent and mitigate disasters,it is crucial to immediately and properly assess the spatial distribution of landslide hazards in the earthquake-affected area.Currently,there are primarily two categories of...In order to prevent and mitigate disasters,it is crucial to immediately and properly assess the spatial distribution of landslide hazards in the earthquake-affected area.Currently,there are primarily two categories of assessment techniques:the physical mechanism-based method(PMBM),which considers the landslide dynamics and has the advantages of effectiveness and proactivity;the environmental factor-based method(EFBM),which integrates the environmental conditions and has high accuracy.In order to obtain the spatial distribution of landslide hazards in the affected area with near realtime and high accuracy,this study proposed to combine the PMBM based on Newmark method with EFBM to form Newmark-Information value model(N-IV),Newmark-Logic regression model(N-LR)and Newmark-Support Vector Machine model(N-SVM)for seismic landslide hazard assessment on the Ludian Mw 6.2 earthquake in Yunnan.The predicted spatial hazard distribution was compared with the actual cataloged landslide inventory,and frequency ratio(FR),and area under the curve(AUC)metrics were used to verify the model's plausibility,performance,and accuracy.According to the findings,the model's accuracy is ranked as follows:N-SVM>N-LR>N-IV>Newmark.With an AUC value of 0.937,the linked N-SVM was discovered to have the best performance.The research results indicate that the physics-environmental coupled model(PECM)exhibits accuracy gains of 46.406%(N-SVM),30.625%(N-LR),and 22.816%(N-IV)when compared to the conventional Newmark technique.It shows varied degrees of improvement from 2.577%to 12.446%when compared to the single EFBM.The study also uses the Ms 6.8 Luding earthquake to evaluate the model,showcasing its trustworthy in forecasting power and steady generalization.Since the suggested PECM in this study can adapt to complicated earthquake-induced landslides situations,it aims to serve as a reference for future research in a similar field,as well as to help with emergency planning and response in earthquakeprone regions with landslides.展开更多
Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geolog...Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geological factors controlling the nature,condition,and distribution of earthquake-induced geohazards can be analyzed.Such insights facilitate earthquake disaster prediction and emergency response planning.The authors combined field investigations and spatial data analysis to examine geohazards induced by seismic events,examining ten earthquakes including the Wenchuan,Yushu,Lushan events,to elucidate the main control factors of seismic geohazard.The authors observed that seismic geohazard occurrence is usually affected by many factors,among which active nature of the seismogenic fault,seismic peak ground acceleration(PGA),topographic slope and geomorphic height differences,and distance from the fault zone and river system are the most important.Compared with strike-slip earthquakes,thrust earthquakes induce more high-altitude and high-speed remote landslides,which can cause great harm.Slopes of 0°–40°are prone to secondary seismic geohazards,which are mainly concentrated 0–6 km from the river system.Secondary geohazards are not only related to seismogenic fault but also influenced by the associated faults in the earthquake area.The maximum seismic PGA and secondary seismic geohazard number are positively correlated,and the horizontal and vertical ground motions play leading and promoting roles in secondary geohazard formation,respectively.Through the research,the spatial distribution of seismic geohazards is predicted,providing a basis for the formulation of emergency response plans following disasters.展开更多
Earthquake-induced gravity variation refers to changes in the earth’s gravity field associated with seismic activities.In recent years,development in the theories has greatly promoted seismic deformation research,lay...Earthquake-induced gravity variation refers to changes in the earth’s gravity field associated with seismic activities.In recent years,development in the theories has greatly promoted seismic deformation research,laying a solid theoretical foundation for the interpretation and application of seismological gravity monitoring.Traditional terrestrial gravity measurements continue to play a significant role in studies of interseismic,co-seismic,and post-seismic gravity field variations.For instance,superconducting gravimeter networks can detect co-seismic gravity change at the sub-micro Gal level.At the same time,the successful launch of satellite gravity missions(e.g.,the Gravity Recovery and Climate Experiment or GRACE)has also facilitated applied studies of the gravity variation associated with large earthquakes,and several remarkable breakthroughs have been achieved.The progress in gravity observation technologies(e.g.,GRACE and superconducting gravimetry)and advances in the theories have jointly promoted seismic deformation studies and raised many new research topics.For example,superconducting gravimetry has played an important role in analyses of episodic tremor,slow-slip events,and interseismic strain patterns;the monitoring of transient gravity signals and related theories have provided a new perspective on earthquake early warning systems;the mass transport detected by the GRACE satellites several months before an earthquake has brought new insights into earthquake prediction methods;the use of artificial intelligence to automatically identify tiny gravity change signals is a new approach to accurate and rapid determination of earthquake magnitude and location.Overall,many significant breakthroughs have been made in recent years,in terms of the theory,application,and observation measures.This article summarizes the progress,with the aim of providing a reference for seismologists and geodetic researchers studying the phenomenon of gravity variation,advances in related theories and applications,and future research directions in this discipline.展开更多
Many natural landscapes that lie in high mountain regions are highly susceptible to geological hazards, and their values and integrity are strongly threatened by the hazards. A preliminary framework was proposed to un...Many natural landscapes that lie in high mountain regions are highly susceptible to geological hazards, and their values and integrity are strongly threatened by the hazards. A preliminary framework was proposed to undertake a quantitative assessment of the impact of earthquake-induced geological hazards on the natural landscapes. Four factors reflecting the aesthetic value, ecological value, integrity of landscapes were selected to assess their vulnerability. The impact of earthquake-induced geological hazards on the landscapes is quantitatively expressed as the product of their vulnerability and resilience. The assessment framework was applied to Jiuzhaigou Valley which was severely struck by the Ms 7.0 earthquake on August 8, 2017. Field survey, satellite image interpretation, high-resolution DEM and unmanned aerial vehicle(UAV) reconnaissance were used to retrieve the values of the assessment factors. Twenty seven World Heritage Sites in the valley strongly influenced by the earthquakeinduced geohazards were evaluated. The impact values of two sites of them(Sparking Lake and Nuorilang Waterfall) are up to 8.24 and 4.65, respectively, and their natural landscapes were greatly damaged. The assessment results show a good agreement with the actual damages of the heritage sites.展开更多
Geohazards induced by the Lushan Ms 7.0 earthquake on April 20, 2013 mainly have four types: collapse, landslide, slope debris flow, and sand-soil liquefaction. These geohazards mainly occurred near the epicenter, on...Geohazards induced by the Lushan Ms 7.0 earthquake on April 20, 2013 mainly have four types: collapse, landslide, slope debris flow, and sand-soil liquefaction. These geohazards mainly occurred near the epicenter, on steep slopes or below cliffs in high mountain and deep valley areas, and at or near fault ends. They have no obvious relationships to active faults, but their relationships to the weathering degree and structures of rock and rock mass are obvious. Compared with the Wenchuan Ms 8.0 earthquake on May 12, 2008, the Lnshan earthquake is relatively little in the impact force and the throwing amount. All of these should be related to the magnitude of this earthquake, not very large but not very little. This character of the Lushan earthquake would make some processes uncompleted so as to bring about some concealed geohazards. Finally, in order to deal with challenges presented by such conceal geohazards, some brief recommendations are put forward.展开更多
The rapid identification based on InSAR technology was proved to be effective in our emergency investigation of surface ruptures and geohazards induced by the Yushu earthquake.The earthquake-generating fault of the Yu...The rapid identification based on InSAR technology was proved to be effective in our emergency investigation of surface ruptures and geohazards induced by the Yushu earthquake.The earthquake-generating fault of the Yushu earthquake is the Yushu section of the Garze-Yushu faults zone.It strikes NWW-NW,23 km long near the Yushu County seat,dominated by left-lateral strike slip,and appearing as a surface rupture zone.The macroscopic epicenter is positioned at Guo-yang-yan -song-duo of Gyegu Town(33°03'11"N,96°51'26"E),where the co-seismic horizontal offset measured is 1.75 m.Geohazards induced by the Yushu earthquake are mainly rockfalls,landslides,debris flows, and unstable slopes.They are controlled by the earthquake-generating fault and are mostly distributed along it.There are several geohazard chains having been established,such as earthquake,canal damage,soil liquefying,landslide-debris flow,earthquake,soil liquefying,roadbed deformation,etc.In order to prevent seismic hazards,generally,where there is a visible surface rupture induced by the Yushu earthquake,reconstruction should be at least beyond 20 m,on each side,from it.Sufficient attention should also be given to potential geohazards or geohazard chains induced by the earthquake.展开更多
With offshore resource exploration moving to the deep water, marine geohazards have been attracting attention from the academic and industry. Research achievements of marine geohazards were reviewed in this paper. We ...With offshore resource exploration moving to the deep water, marine geohazards have been attracting attention from the academic and industry. Research achievements of marine geohazards were reviewed in this paper. We analyzed and discussed typical issues among marine geohazards, including coastal erosion, submarine slope failure, turbidity current and special hazards induced by gas hydrate dissociation, in terms of their definition, distribution, characteristics and case studies. Major international projects on marine geohazards headed by the United States, Europe, Japan and other international organizations are introduced as well. Three marine geohazard survey methods, including geophysical survey, geotechnical exploration and in-situ observation, were summarized with a brief description of each approach, respectively. Especially, the history of marine geohazard researches in China is briefly reviewed, showing the disparity between China and developed countries in the study of marine geohazards narrows gradually. The potential research tendency in future was suggested.展开更多
Various geological processes and features that might inflict hazards identified in the South China Sea by using new technologies and methods.These features include submarine landslides,pockmark fields,shallow free gas...Various geological processes and features that might inflict hazards identified in the South China Sea by using new technologies and methods.These features include submarine landslides,pockmark fields,shallow free gas,gas hydrates,mud diapirs and earthquake tsunami,which are widely distributed in the continental slope and reefal islands of the South China Sea.Although the study and assessment of geohazards in the South China Sea came into operation only recently,advances in various aspects are evolving at full speed to comply with National Marine Strategy and‘the Belt and Road’Policy.The characteristics of geohazards in deep-water seafloor of the South China Sea are summarized based on new scientific advances.This progress is aimed to aid ongoing deep-water drilling activities and decrease geological risks in ocean development.展开更多
The hazard assessment of potential earthquake-induced landslides is an important aspect of the study of earthquake-induced landslides. In this study, we assessed the hazard of potential earthquake-induced landslides i...The hazard assessment of potential earthquake-induced landslides is an important aspect of the study of earthquake-induced landslides. In this study, we assessed the hazard of potential earthquake-induced landslides in Huaxian County with a new hazard assessment method. This method is based on probabilistic seismic hazard analysis and the Newmark cumulative displacement assessment model. The model considers a comprehensive suite of information, including the seismic activities and engineering geological conditions in the study area, and simulates the uncertainty of the intensity parameters of the engineering geological rock groups using the Monte Carlo method. Unlike previous assessment studies on ground motions with a given exceedance probability level, the hazard of earthquake-induced landslides obtained by the method presented in this study allows for the possibility of earthquake-induced landslides in different parts of the study area in the future. The assessment of the hazard of earthquake-induced landslides in this study showed good agreement with the historical distribution of earthquake-induced landslides. This indicates that the assessment properly reflects the macroscopic rules for the development of earthquake-induced landslides in the study area, and can provide a reference framework for the management of the risk of earthquakeinduced landslides and land planning.展开更多
This paper discusses the rational exploitation of main resources and prevention of geohazards in karst regions. There exist relationship chains between natural disasters in the earth, which include the chain between g...This paper discusses the rational exploitation of main resources and prevention of geohazards in karst regions. There exist relationship chains between natural disasters in the earth, which include the chain between geological hazards and climatic hazards, the chain between geological hazards and biogenic hazards as well as the one between geological hazards. Irrational exploitation of all resources will inevitably cause hazards. Therefore it is very important to discuss the problem related to prevention of geohazards by rational exploitation of resources.展开更多
The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary r...The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary results indicate that secondary effects of the earthquake will affect specific areas, including those with glutenite and carbonate bedrock, a seismic intensity of IX, slopes between 40° and 50°, elevations of less than 2500 m, slope change rates between 20° and 30°, slope curvatures from - 1 to -0.5 and 0. 5 to 1, and relief between 50 and 100 m. Regions with susceptibility indices greater than 0.71 are prone to landslides and collapses. The secondary features are mainly distributed on both sides of the ridges that extend from Baosheng to Shuangshi and from Baosheng to Longxing. Other features are scattered on both sides of the ridges that extend from Qishuping to Baosheng and from Masangping to Lingguan. The distribution of the earthquake-related features trends in the NE direction, and the area that was most affected by the Lushan earthquake covers approximately 52.4 km^2.展开更多
As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially foll...As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially following a strong earthquake, is one of common geological disasters known in rock slope engineering. Therefore, it is important to study the collapse mechanism of dangerous rock masses induced by an earthquake and the analysis approach of its stability. This study provides a simple and convenient method to determine the collapse mechanisms of two types of dangerous rock masses (i.e. cantilever and upright) associated with the definition and calculation of the safety factor, which is based on the flexure theory of a constant-section beam by combining with the maximum tensile-stress criterion to depict the process of crack propagation caused by seismic waves. The calculation results show that there are critical crack depths in each form of the dangerous rock masses. Once the accumulated depth of the crack growth during an earthquake exceeds the critical depth, the collapse will occur. It is also demonstrated that the crack extension amount of each step is not a constant value, and is closely associated with the current accumulated crack depth. The greater the cumulative crack depth, the more easily the crack propagates. Finally, the validity and applicability of the proposed method are verified through two actual engineering examples.展开更多
China has been affected by some of the world’s most serious geological disasters and experiences high economic damage every year.Geohazards occur not only in remote areas but also in highly populated cities.In the fr...China has been affected by some of the world’s most serious geological disasters and experiences high economic damage every year.Geohazards occur not only in remote areas but also in highly populated cities.In the framework of the Dragon-432365 Project,this paper presents the main results and the major conclusions derived from an extensive exploitation of Sentinel-1,ALOS-2(Advanced Land Observing Satellite 2),GF-3(Gao Fen Satellite 3),and latest launched SAR(Synthetic Aperture Radar),together with methods that allow the evaluation of their importance for various geohazards.Therefore,in the scope of this project,the great benefits of recent remote sensing data(wide spatial and temporal coverage)that allow a detailed reconstruction of past displacement events and to monitor currently occurring phenomena are exploited to study different areas and geohazards problems,including:surface deformation of mountain slopes;identification and monitoring of ground movements and subsidence;landslides;ground fissure;and building inclination studies.Suspicious movements detected in the different study areas were cross validated with different SAR sensors and truth data.展开更多
We want to talk about the geohazards in Pamir mountains,in Tajikistan,using different materials and researches about it.Also we are trying to look deeply into this problem,and want to research how about
Geohazards,such as earthquakes,landslides, tsunamis,volcanic eruptions,floods,melting permafrost, and metastable soils impact people’s lives worldwide.Population growth is forcing people to live in areas that have cl...Geohazards,such as earthquakes,landslides, tsunamis,volcanic eruptions,floods,melting permafrost, and metastable soils impact people’s lives worldwide.Population growth is forcing people to live in areas that have classically supported low population densities including steep slopes,low-lying coasts,and along floodplains and currently climate change is exacerbating risk in these regions.展开更多
The permanent displacement of seismic slopes can be regarded as an effective criterion for stability estimation. This paper studied the characteristics of permanent displacements induced by velocity pulse-like ground ...The permanent displacement of seismic slopes can be regarded as an effective criterion for stability estimation. This paper studied the characteristics of permanent displacements induced by velocity pulse-like ground motions and developed an empirical model to readily evaluate the stability of seismic slopes in a near-fault region. We identified 264 velocity pulse-like ground motions from the Next Generation Attenuation(NGA) database using the latest improved energy-based approach. All selected ground motions were rotated to the orientation of the strongest observed pulse for considering the directivity of the pulse effect, so that the most dangerous condition for slopes was considered. The results show the velocity pulse-like ground motions have a much more significant effect on permanent displacement of slopes than non-pulse-like ground motions. A regression model based on a function of peak ground velocity(PGV), peak ground acceleration(PGA) and critical acceleration(ac), was generated. A significant difference was found by comparing the presented model with classical models from literatures. This model can be used to evaluate the seismic slope stability considering the effects of nearfault pulse-like characteristics.展开更多
文摘Across a gradient belt of the Western Sichuan Plateau,geohazards have seriously limited economic and social development.According to incomplete statistics,15,673 geohazards have been recorded in the study area.In order to mitigate the threat of geohazards to human engineering activities in the region,an overall understanding of the distribution pattern of geohazards and susceptibility assessment are necessary.In this paper,a gradient belt of the Western Sichuan Plateau and its zoning criteria were defined.Subsequently,on the basis of relief amplitude,distance to faults,rainfall,and human activities,three indicators of endogenic process were introduced:Bouguer gravity anomaly gradient,vertical deformation gradient,and horizontal deformation gradient.Thereafter,the distribution patterns of geohazards were investigated through mathematical statistics and ArcGIS software.By randomly selecting 10,449 hazards,a geohazard susceptibility map was generated using the Information Value(IV)model.Finally,the IV model was validated against 5224 hazards using the Area Under Curve(AUC)method.The results show that 47.6%of the geohazards were distributed in the zone of steep slope.Geohazards showed strong responses to distance to faults,human activities,and annual rainfall.The distribution of geohazards in the gradient belt of the Western Sichuan Plateau is more sensitive to vertical internal dynamics factors(such as vertical deformation gradient and Bouguer gravity anomaly gradient)without any apparent sensitivity to horizontal internal dynamics factors.The areas of high and very-high risk account for up to 32.22%,mainly distributed in the Longmenshan and Anning River faults.According to the AUC plot,the success rate of the IV model for generating the susceptibility map is 76%.This susceptibility map and geohazard distribution pattern can provide a reference for geological disaster monitoring,preparation of post-disaster emergency measures,and town planning.
基金funded by Chang’an University(Xi’an,China)through the National Key Research&Development Program of China(2020YFC1512003)。
文摘Geohazards along highways are the main natural hazards that could affect the safety and operation of highway systems.Understanding the risks faced by highways in areas affected by geohazards is an urgent problem to be solved.This study used historical geohazard events from Sichuan Province and highway network data to propose a geohazard risk index that reflects the risk geohazards along highways.Furthermore,this work applied the entropy method and expert scoring to calculate the weight of the index.The spatial distributions of landslides,debris flows,collapses,and unstable slopes along the highways were analysed based on ArcGIS spatial statistics,and the highway geohazard intensity index were obtained.The relationships between slope,rainfall,vegetation coverage,rock type,land use,and incision depth with geohazards were analysed,and the highway geohazard susceptibility index was calculated by the weighted information method.Based on the intensity and susceptibility index,we obtained a geohazard risk index which can better evaluate the risk of highways,and made a highway geohazard risk map to aid the prevention and mitigation of geohazards along highways and assist with highway network planning.
基金financially supported by the National Natural Science Foundation of China(41977213)The Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0906)+3 种基金Fundamental Research Funds for the Central Universities(XJ2021KJZK039)Sichuan Provincial Transportation Science and Technology Project(2021-A-03)China Road&Bridge Corporation(P220447)Research on the mechanism of dynamic disaster and key technology of protection for slope engineering in the high-intensity red layer area of Heilongtan(R110121H01092)。
文摘In order to prevent and mitigate disasters,it is crucial to immediately and properly assess the spatial distribution of landslide hazards in the earthquake-affected area.Currently,there are primarily two categories of assessment techniques:the physical mechanism-based method(PMBM),which considers the landslide dynamics and has the advantages of effectiveness and proactivity;the environmental factor-based method(EFBM),which integrates the environmental conditions and has high accuracy.In order to obtain the spatial distribution of landslide hazards in the affected area with near realtime and high accuracy,this study proposed to combine the PMBM based on Newmark method with EFBM to form Newmark-Information value model(N-IV),Newmark-Logic regression model(N-LR)and Newmark-Support Vector Machine model(N-SVM)for seismic landslide hazard assessment on the Ludian Mw 6.2 earthquake in Yunnan.The predicted spatial hazard distribution was compared with the actual cataloged landslide inventory,and frequency ratio(FR),and area under the curve(AUC)metrics were used to verify the model's plausibility,performance,and accuracy.According to the findings,the model's accuracy is ranked as follows:N-SVM>N-LR>N-IV>Newmark.With an AUC value of 0.937,the linked N-SVM was discovered to have the best performance.The research results indicate that the physics-environmental coupled model(PECM)exhibits accuracy gains of 46.406%(N-SVM),30.625%(N-LR),and 22.816%(N-IV)when compared to the conventional Newmark technique.It shows varied degrees of improvement from 2.577%to 12.446%when compared to the single EFBM.The study also uses the Ms 6.8 Luding earthquake to evaluate the model,showcasing its trustworthy in forecasting power and steady generalization.Since the suggested PECM in this study can adapt to complicated earthquake-induced landslides situations,it aims to serve as a reference for future research in a similar field,as well as to help with emergency planning and response in earthquakeprone regions with landslides.
基金supported by the National Natural Science Foundation of China(41977258)the National Key Research and Development Program of China(2017YFC1501005 and 2018YFC1504704)。
文摘Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geological factors controlling the nature,condition,and distribution of earthquake-induced geohazards can be analyzed.Such insights facilitate earthquake disaster prediction and emergency response planning.The authors combined field investigations and spatial data analysis to examine geohazards induced by seismic events,examining ten earthquakes including the Wenchuan,Yushu,Lushan events,to elucidate the main control factors of seismic geohazard.The authors observed that seismic geohazard occurrence is usually affected by many factors,among which active nature of the seismogenic fault,seismic peak ground acceleration(PGA),topographic slope and geomorphic height differences,and distance from the fault zone and river system are the most important.Compared with strike-slip earthquakes,thrust earthquakes induce more high-altitude and high-speed remote landslides,which can cause great harm.Slopes of 0°–40°are prone to secondary seismic geohazards,which are mainly concentrated 0–6 km from the river system.Secondary geohazards are not only related to seismogenic fault but also influenced by the associated faults in the earthquake area.The maximum seismic PGA and secondary seismic geohazard number are positively correlated,and the horizontal and vertical ground motions play leading and promoting roles in secondary geohazard formation,respectively.Through the research,the spatial distribution of seismic geohazards is predicted,providing a basis for the formulation of emergency response plans following disasters.
文摘Earthquake-induced gravity variation refers to changes in the earth’s gravity field associated with seismic activities.In recent years,development in the theories has greatly promoted seismic deformation research,laying a solid theoretical foundation for the interpretation and application of seismological gravity monitoring.Traditional terrestrial gravity measurements continue to play a significant role in studies of interseismic,co-seismic,and post-seismic gravity field variations.For instance,superconducting gravimeter networks can detect co-seismic gravity change at the sub-micro Gal level.At the same time,the successful launch of satellite gravity missions(e.g.,the Gravity Recovery and Climate Experiment or GRACE)has also facilitated applied studies of the gravity variation associated with large earthquakes,and several remarkable breakthroughs have been achieved.The progress in gravity observation technologies(e.g.,GRACE and superconducting gravimetry)and advances in the theories have jointly promoted seismic deformation studies and raised many new research topics.For example,superconducting gravimetry has played an important role in analyses of episodic tremor,slow-slip events,and interseismic strain patterns;the monitoring of transient gravity signals and related theories have provided a new perspective on earthquake early warning systems;the mass transport detected by the GRACE satellites several months before an earthquake has brought new insights into earthquake prediction methods;the use of artificial intelligence to automatically identify tiny gravity change signals is a new approach to accurate and rapid determination of earthquake magnitude and location.Overall,many significant breakthroughs have been made in recent years,in terms of the theory,application,and observation measures.This article summarizes the progress,with the aim of providing a reference for seismologists and geodetic researchers studying the phenomenon of gravity variation,advances in related theories and applications,and future research directions in this discipline.
基金supported by "8.8" Jiuzhaigou earthquake stricken area ecological disaster prevention and control of key scientific and technological support project of Land and Resources Department of Sichuan Province(Research on Prevention and Control Technology of Ecological Debris Flow Disasters)(Grant No.KJ-2018-24)the National Natural Science Foundation of China(Grant No.41790434 and 41601011)
文摘Many natural landscapes that lie in high mountain regions are highly susceptible to geological hazards, and their values and integrity are strongly threatened by the hazards. A preliminary framework was proposed to undertake a quantitative assessment of the impact of earthquake-induced geological hazards on the natural landscapes. Four factors reflecting the aesthetic value, ecological value, integrity of landscapes were selected to assess their vulnerability. The impact of earthquake-induced geological hazards on the landscapes is quantitatively expressed as the product of their vulnerability and resilience. The assessment framework was applied to Jiuzhaigou Valley which was severely struck by the Ms 7.0 earthquake on August 8, 2017. Field survey, satellite image interpretation, high-resolution DEM and unmanned aerial vehicle(UAV) reconnaissance were used to retrieve the values of the assessment factors. Twenty seven World Heritage Sites in the valley strongly influenced by the earthquakeinduced geohazards were evaluated. The impact values of two sites of them(Sparking Lake and Nuorilang Waterfall) are up to 8.24 and 4.65, respectively, and their natural landscapes were greatly damaged. The assessment results show a good agreement with the actual damages of the heritage sites.
基金financially supported by the Project of China Special Project of Basic Work of Science and Technology (2011FY110100-2)Project of the 12th Five-year National Sci-Tech Support Plan of China (grant No. 2011BAK12B09)+1 种基金the National Science Foundation of China (grant No. 41072269)China Geological Survey (grant No. 1212010914025)
文摘Geohazards induced by the Lushan Ms 7.0 earthquake on April 20, 2013 mainly have four types: collapse, landslide, slope debris flow, and sand-soil liquefaction. These geohazards mainly occurred near the epicenter, on steep slopes or below cliffs in high mountain and deep valley areas, and at or near fault ends. They have no obvious relationships to active faults, but their relationships to the weathering degree and structures of rock and rock mass are obvious. Compared with the Wenchuan Ms 8.0 earthquake on May 12, 2008, the Lnshan earthquake is relatively little in the impact force and the throwing amount. All of these should be related to the magnitude of this earthquake, not very large but not very little. This character of the Lushan earthquake would make some processes uncompleted so as to bring about some concealed geohazards. Finally, in order to deal with challenges presented by such conceal geohazards, some brief recommendations are put forward.
基金supported by the National Natural Science Foundation of China(grant No.40902059)the Land Resource Survey Project of China Geological Survey (grant No.1212010914025,No.1212011014035)the Fundamental Research Fund of Institute of Geomechanics, CAGS(grant No.DZLXJK200906)
文摘The rapid identification based on InSAR technology was proved to be effective in our emergency investigation of surface ruptures and geohazards induced by the Yushu earthquake.The earthquake-generating fault of the Yushu earthquake is the Yushu section of the Garze-Yushu faults zone.It strikes NWW-NW,23 km long near the Yushu County seat,dominated by left-lateral strike slip,and appearing as a surface rupture zone.The macroscopic epicenter is positioned at Guo-yang-yan -song-duo of Gyegu Town(33°03'11"N,96°51'26"E),where the co-seismic horizontal offset measured is 1.75 m.Geohazards induced by the Yushu earthquake are mainly rockfalls,landslides,debris flows, and unstable slopes.They are controlled by the earthquake-generating fault and are mostly distributed along it.There are several geohazard chains having been established,such as earthquake,canal damage,soil liquefying,landslide-debris flow,earthquake,soil liquefying,roadbed deformation,etc.In order to prevent seismic hazards,generally,where there is a visible surface rupture induced by the Yushu earthquake,reconstruction should be at least beyond 20 m,on each side,from it.Sufficient attention should also be given to potential geohazards or geohazard chains induced by the earthquake.
基金granted by the National Natural Science Foundation of China(Grant No.41427803)
文摘With offshore resource exploration moving to the deep water, marine geohazards have been attracting attention from the academic and industry. Research achievements of marine geohazards were reviewed in this paper. We analyzed and discussed typical issues among marine geohazards, including coastal erosion, submarine slope failure, turbidity current and special hazards induced by gas hydrate dissociation, in terms of their definition, distribution, characteristics and case studies. Major international projects on marine geohazards headed by the United States, Europe, Japan and other international organizations are introduced as well. Three marine geohazard survey methods, including geophysical survey, geotechnical exploration and in-situ observation, were summarized with a brief description of each approach, respectively. Especially, the history of marine geohazard researches in China is briefly reviewed, showing the disparity between China and developed countries in the study of marine geohazards narrows gradually. The potential research tendency in future was suggested.
基金funded by the MOST 973 program (No. 2015CB251201)the Guangzhou Marine Geology Survey project (Nos. GZH201400210 and GZH201601040) the National Natural Science Foundation of China (Nos. 91228208 and 41666012)
文摘Various geological processes and features that might inflict hazards identified in the South China Sea by using new technologies and methods.These features include submarine landslides,pockmark fields,shallow free gas,gas hydrates,mud diapirs and earthquake tsunami,which are widely distributed in the continental slope and reefal islands of the South China Sea.Although the study and assessment of geohazards in the South China Sea came into operation only recently,advances in various aspects are evolving at full speed to comply with National Marine Strategy and‘the Belt and Road’Policy.The characteristics of geohazards in deep-water seafloor of the South China Sea are summarized based on new scientific advances.This progress is aimed to aid ongoing deep-water drilling activities and decrease geological risks in ocean development.
基金funded by the National Natural Science Foundation of China(41572313)Geological Survey Project(12120114035501)the China National Special Fund for Earthquake Scientific Research(201408014)
文摘The hazard assessment of potential earthquake-induced landslides is an important aspect of the study of earthquake-induced landslides. In this study, we assessed the hazard of potential earthquake-induced landslides in Huaxian County with a new hazard assessment method. This method is based on probabilistic seismic hazard analysis and the Newmark cumulative displacement assessment model. The model considers a comprehensive suite of information, including the seismic activities and engineering geological conditions in the study area, and simulates the uncertainty of the intensity parameters of the engineering geological rock groups using the Monte Carlo method. Unlike previous assessment studies on ground motions with a given exceedance probability level, the hazard of earthquake-induced landslides obtained by the method presented in this study allows for the possibility of earthquake-induced landslides in different parts of the study area in the future. The assessment of the hazard of earthquake-induced landslides in this study showed good agreement with the historical distribution of earthquake-induced landslides. This indicates that the assessment properly reflects the macroscopic rules for the development of earthquake-induced landslides in the study area, and can provide a reference framework for the management of the risk of earthquakeinduced landslides and land planning.
文摘This paper discusses the rational exploitation of main resources and prevention of geohazards in karst regions. There exist relationship chains between natural disasters in the earth, which include the chain between geological hazards and climatic hazards, the chain between geological hazards and biogenic hazards as well as the one between geological hazards. Irrational exploitation of all resources will inevitably cause hazards. Therefore it is very important to discuss the problem related to prevention of geohazards by rational exploitation of resources.
基金supported by the Director Foundation of the Institute of Seismology,China Earthquake Administration(201056076,201116002)
文摘The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary results indicate that secondary effects of the earthquake will affect specific areas, including those with glutenite and carbonate bedrock, a seismic intensity of IX, slopes between 40° and 50°, elevations of less than 2500 m, slope change rates between 20° and 30°, slope curvatures from - 1 to -0.5 and 0. 5 to 1, and relief between 50 and 100 m. Regions with susceptibility indices greater than 0.71 are prone to landslides and collapses. The secondary features are mainly distributed on both sides of the ridges that extend from Baosheng to Shuangshi and from Baosheng to Longxing. Other features are scattered on both sides of the ridges that extend from Qishuping to Baosheng and from Masangping to Lingguan. The distribution of the earthquake-related features trends in the NE direction, and the area that was most affected by the Lushan earthquake covers approximately 52.4 km^2.
基金Scientific Research Fund of the Hebei Education Department under Grant No.QN2015166
文摘As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially following a strong earthquake, is one of common geological disasters known in rock slope engineering. Therefore, it is important to study the collapse mechanism of dangerous rock masses induced by an earthquake and the analysis approach of its stability. This study provides a simple and convenient method to determine the collapse mechanisms of two types of dangerous rock masses (i.e. cantilever and upright) associated with the definition and calculation of the safety factor, which is based on the flexure theory of a constant-section beam by combining with the maximum tensile-stress criterion to depict the process of crack propagation caused by seismic waves. The calculation results show that there are critical crack depths in each form of the dangerous rock masses. Once the accumulated depth of the crack growth during an earthquake exceeds the critical depth, the collapse will occur. It is also demonstrated that the crack extension amount of each step is not a constant value, and is closely associated with the current accumulated crack depth. The greater the cumulative crack depth, the more easily the crack propagates. Finally, the validity and applicability of the proposed method are verified through two actual engineering examples.
基金National Natural Science Foundation of China(Nos.41590852,42071453)。
文摘China has been affected by some of the world’s most serious geological disasters and experiences high economic damage every year.Geohazards occur not only in remote areas but also in highly populated cities.In the framework of the Dragon-432365 Project,this paper presents the main results and the major conclusions derived from an extensive exploitation of Sentinel-1,ALOS-2(Advanced Land Observing Satellite 2),GF-3(Gao Fen Satellite 3),and latest launched SAR(Synthetic Aperture Radar),together with methods that allow the evaluation of their importance for various geohazards.Therefore,in the scope of this project,the great benefits of recent remote sensing data(wide spatial and temporal coverage)that allow a detailed reconstruction of past displacement events and to monitor currently occurring phenomena are exploited to study different areas and geohazards problems,including:surface deformation of mountain slopes;identification and monitoring of ground movements and subsidence;landslides;ground fissure;and building inclination studies.Suspicious movements detected in the different study areas were cross validated with different SAR sensors and truth data.
文摘We want to talk about the geohazards in Pamir mountains,in Tajikistan,using different materials and researches about it.Also we are trying to look deeply into this problem,and want to research how about
文摘Geohazards,such as earthquakes,landslides, tsunamis,volcanic eruptions,floods,melting permafrost, and metastable soils impact people’s lives worldwide.Population growth is forcing people to live in areas that have classically supported low population densities including steep slopes,low-lying coasts,and along floodplains and currently climate change is exacerbating risk in these regions.
基金financial support from the National Natural Science Foundation of China (41672286, 41761144080 and 41530639)Science &Technology Department of Sichuan Province (2017JQ0042)+2 种基金Ministry of Science and Technology of China (KY201801005)State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining & Technology (SKLGDUEK1806)Innovation-Driven Project of Central South University (No. 2019CX011)
文摘The permanent displacement of seismic slopes can be regarded as an effective criterion for stability estimation. This paper studied the characteristics of permanent displacements induced by velocity pulse-like ground motions and developed an empirical model to readily evaluate the stability of seismic slopes in a near-fault region. We identified 264 velocity pulse-like ground motions from the Next Generation Attenuation(NGA) database using the latest improved energy-based approach. All selected ground motions were rotated to the orientation of the strongest observed pulse for considering the directivity of the pulse effect, so that the most dangerous condition for slopes was considered. The results show the velocity pulse-like ground motions have a much more significant effect on permanent displacement of slopes than non-pulse-like ground motions. A regression model based on a function of peak ground velocity(PGV), peak ground acceleration(PGA) and critical acceleration(ac), was generated. A significant difference was found by comparing the presented model with classical models from literatures. This model can be used to evaluate the seismic slope stability considering the effects of nearfault pulse-like characteristics.