Characteristics and Prevention of Secondary Geological Disasters of Wenchuan Earthquake

In the research, secondary geological disasters of Wenchuan earthquake were defined and the consequences were illustrated based on geological disasters, such as collapse, landslide and debris flow, and threats of barrier lakes. In addition, the characteristics of secondary disasters were analyzed, as follows： Rupture of geological faults lays foundation in terms of geological structure; loose solids provide resources of an earthquake; abundant rainfall and large runoffs are driving forces of an earthquake; rainstorm, flood, and long-term high temperature are major inducing factors. Furthermore, suggestions on prevention of secondary disasters were proposed in terms of prevention before, at and after an earthquake. Finally, the scientific and practical significances of secondary disasters were illustrated.

RS and GIS-based Statistical Analysis of Secondary Geological Disasters after the 2008 Wenchuan Earthquake

Using RS and GIS means, this article analyzes the general geological characteristics and the structural belt distribution features in Wenchuan County, Sichuan province, P.R. China as well as the characteristics of the large-scale landslides, mud-rock flows, earthquake lakes, etc., after the earthquake on May 12, 2008. Based on the above work, comprehensive indoor and outdoor research is launched on disaster distribution characteristics and their relationship with earthquakes, terrains, strata, lithology, and structures. Weights of evidence method is utilized to quantitatively analyze and evaluate the spatial distribution of secondary geological disasters after the earthquake occurred. 3 remedying grades for secondary geological disasters are derived from the results of the weights of Evidence, followed by suggestions given to remedy earthquake secondary disasters.

Risk Assessment of Secondary Geological Disasters Induced by the Yushu Earthquake

The Yushu Ms 7.1 earthquake occurred on April 14,2010 in Qinghai Province,China.It induced a mass of secondary geological disasters,such as collapses,landslides,and debris flows.Risk assessment maps are important for geological disaster prevention and mitigation,and also can serve as a guide for post-earthquake reconstruction.Firstly,a hazard assessment index system of secondary geological disasters in the earthquake region was built in this paper,which was based on detailed analysis of environmental and triggering factors closely related to geological disasters in the study area.GIS technology was utilized to extract and analyze the assessment index.Hazard assessment maps of secondary geological disasters were obtained by spatial modeling and overlaying analysis.Secondly,an analysis of the vulnerability of hazard bearing bodies in the area was conducted,important information,such as, population density,percentage of arable land, industrial and agricultural outputs per unit area were regarded as assessment indices to evaluate socioeconomic vulnerability.Thirdly,the risk level of secondary geological disasters of the area was obtained by the formula:Risk=Hazard×Vulnerability. Risk assessment maps were categorized into four levels,including"low","moderate","high"and"very high".These results show that some urban areas are at very high risk,including Jiegu,Chengwen,Xiaxiula and Sahuteng towns.This research can provide some references and suggestions to improve decisionmaking support for emergency relief and post- earthquake reconstruction in the study area.

New Thought of Meteorological Forecasting and Warning Models of Geological Disasters in Loess Plateau of North Shaanxi

The study established daily comprehensive precipitation equations and calculated respective critical daily comprehensive precipitation value of loess-collapse disasters and landslide disasters by dint of the geological disasters and corresponding precipitation data in 47 years.Considering geological disaster risk divisions,precipitation influence coefficient and daily comprehensive precipitation,hourly rolling daily-forecasting and hourly warning fine and no-gap models on the base of high temporal and spatial resolution rainfall data of automatic meteorological station were developed.Through the verifying of combination of dynamical forecasting model and warning model,the results showed that it can improve efficiency of forecast and have good response at the same time.

Factor analysis of earthquake-induced geological disasters of the M7.0 Lushan earthquake in China

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.

Study on the Analysis System of Meteorological and Geological Disaster Grades Early Warning of WebGIS

The method of realizing meteorological and geological disaster forecast and early warning information system in Qixian County of Shanxi Province was studied. According to meteorological factor parameter of the geological disasters for many years in Qixian County Land Bureau, and data of average meteorological element parameters that corresponded by evolution of geological disaster region each year, evaluation algorithm model of the forecast and eady warning of geological disasters in Qixian County was obtained, and the database of meteorological factor of geological disaster was established. On this basis, WebGIS geographic information system based on C/S and B/S which could real-time monitor geological disaster region was studied and designed. After data analysis system could evaluate the geological disaster forecast and early warning and make the real-time and accurate early warning, which greatly improved the timeliness of meteorological geological disasters forecast and early warning in Qixian County. System set of data processing and forecast and early warning issued in one, to realize the dynamic information release function of grade of geological disaster early warning, and had the characteristics of easy sharing, real-time dynamic update.

Construction of Forecast and Early Warning System of Meteorological and Geological Disasters in Qinghai Province

Based on the meteorological and geological disaster data, ground observation data set, CLDAS grid point data set, and EC, BJ and other model product data during 2008-2020, the temporal and spatial distribution characteristics of meteorological and geological disasters and precipitation were analyzed, and the causes of the occurrence of meteorological geological disasters and the deviation of model precipitation forecast were revealed. Besides, an objective precipitation forecast system and a forecast and early warning system of meteorological and geological disasters were established. The results show that meteorological and geological disasters and precipitation were mainly concentrated from May to October, of which continuous precipitation appeared frequently in June and September, and convective precipitation was mainly distributed in July-August;the occurrence frequency of meteorological and geological disasters was basically consistent with the distribution of accumulated precipitation and short-term heavy precipitation, and they were mainly concentrated in the southern and eastern parts of Qinghai. Meteorological and geological disasters were basically caused by heavy rain and above, and meteorological and geological disasters were divided into three types: continuous precipitation(type I), short-term heavy precipitation(type II) and mixed precipitation(type III). For type I, the early warning conditions of meteorological and geological disasters in Qinghai are as follows: if the soil volumetric water content difference between 0-10 and 10-40 cm is ≤0.03 mm^(3)/mm^(3), or the soil volumetric water content at one of the depths is ≥0.25 mm^(3)/mm^(3), the future effective precipitation reaches 8.4 mm in 1 h, 10.2 mm in 2 h, 11.5 mm in 3 h, 14.2 mm in 6 h, 17.7 mm in 12 h, and 18.2 mm in 24 h, and such warning conditions are mainly used in Yushu, Guoluo, southern Hainan, southern Huangnan and other places. For type II, when the future effective precipitation is up to 11.5 mm in 1 h, 14.9 mm in 2 h, 16.2 mm in 3 h, 19.9 mm in 6 h, 25.3 mm in 12 h, and 26.3 mm in 24 h, such precipitation thresholds are mainly used in Hainan, Huangnan, and eastern Guoluo;as it is up to 13.3 mm in 1 h, 15.5 mm in 2 h, 16.6 mm in 3 h, 19.9 mm in 6 h, 31.1 mm in 12 h, and 34.0 mm in 24 h, such precipitation thresholds are mainly used in Hehuang valley. The precipitation thresholds of type III are between type I and type II, and closer to that of type II;such precipitation thresholds are mainly used in Hainan, Huangnan, and northern Guoluo. The forecasting ability of global models for heavy rain and above was not as good as that of mesoscale numerical prediction model, and global models had a wet bias for small-scale precipitation and a dry bias for large-scale precipitation;meso-scale models had a significantly larger precipitation bias. The forecast ability of precipitation objective forecast system constructed by frequency matching and multi-model integration has improved. At the same time, the constructed grid forecast and early warning system of meteorological and geological disasters is more precise and accurate, and is of instructive significance for the forecast and early warning of meteorological and geological disasters.

Application of Electronic Sand Table System in Geological Disasters Meteorological Service Based on GIS

With complex terrain and developed economy, Zhejiang Province has suffered a lot from the frequent geological disasters, which have done great damages to the construction and development of the whole province. Therefore, it is particularly important to improve the geological disasters meteorological service. Electronic sand table system, a high-tech product of three-dimensional visualization, can provide the geological disaster meteorological service with the intuitive and visual application environment. In this study, we developed electronic sand table system based on GIS and established the geological disasters meteorological service database. In addition, we also analyzed and discussed the applications of meteorological service in online weather forecast, meteorological warning message, and multimedia meteorological electronic display. The application of electronic sand table system in geological disaster meteorological services for disaster prevention and mitigation is of great importance that it provides intuitive terrain analysis data for the forecast of geological disasters warning, which greatly enhances the ability of geological disasters meteorological service.

Analysis on the Relationship between Geological Disasters and Precipitation in Zhuanghe Region

To improve relevance and timeliness of forecasting and early warning for precipitation-type geological disasters in Zhuanghe City, by using case information of geological disasters and corresponding precipitation data in Zhuanghe City during 2009 -2011, the relationship between geological disasters and precipitation was analyzed. Results showed that precipitation-type geological disasters in Zhuanghe City had close relationships with precipitation intensity in prior period and rainfall on the day. The research had important actual significance for prevention of geological disasters.

Study on Quantitative Assessment for the Social Risk of Major Geological Disasters

Based on the analysis of social risk of geological disasters,the index system of social risk evaluation was established. To assess the social risk quantitatively,a quantitative evaluation model of the social risk was established based on AHP,and the social risk of geological disasters was graded. Finally,the evaluation model was applied in a case.

Imbalance Between Scientific Technology and Human Rights and Measures to Rectify the Imbalance——Taking Geological Disasters as an Example

I. Increase in Human Activity and Occurrence of Geological Disasters ＂A geological disaster is a natural disaster that happens in a geo- logical environment. It is a geological effect （phenomenon） caused or in- fluenced by Nature and （or） human factors that leads to losses to human life, property and the environment.TM Based on their cause, geological disasters can be divided into natural geological and artificial geological disasters. Natural geological disas- ters include those caused by natural effects. These include typhoons, rain- fall, melting snow and earthquakes,

Risk assessment of coastal flooding disaster by storm surge based on Elevation-Area method and hydrodynamic models:Taking Bohai Bay as an example

The future inundation by storm surge on coastal areas are currently ill-defined.With increasing global sealevel due to climate change,the coastal flooding by storm surge is more and more frequently,especially in coastal lowland with land subsidence.Therefore,the risk assessment of such inundation for these areas is of great significance for the sustainable socio-economic development.In this paper,the authors use Elevation-Area method and Regional Ocean Model System(ROMS)model to assess the risk of the inundation of Bohai Bay by storm surge.The simulation results of Elevation-Area method show that either a 50-year or 100-year storm surge can inundate coastal areas exceeding 8000 km^(2);the numerical simulation results based on hydrodynamics,considering ground friction and duration of the storm surge high water,show that a 50-year or 100-year storm surge can only inundate an area of over 2000 km^(2),which is far less than 8000 km^(2);while,when taking into account the land subsidence and sea level rise,the very inundation range will rapidly increase by 2050 and 2100.The storm surge will greatly impact the coastal area within about 10-30 km of the Bohai Bay,in where almost all major coastal projects are located.The prompt response to flood disaster due to storm surge is urgently needed,for which five suggestions have been proposed based on the geological background of Bohai Bay.This study may offer insight into the development of the response and adaptive plans for flooding disasters caused by storm surge.

Comparative evaluation of geological disaster susceptibility using multi-regression methods and spatial accuracy validation

Geological disasters not only cause economic losses and ecological destruction, but also seriously threaten human survival. Selecting an appropriate method to evaluate susceptibility to geological disasters is an important part of geological disaster research. The aims of this study are to explore the accuracy and reliability of multi-regression methods for geological disaster susceptibility evaluation, including Logistic Regression(LR), Spatial Autoregression(SAR), Geographical Weighted Regression(GWR), and Support Vector Regression(SVR), all of which have been widely discussed in the literature. In this study, we selected Yunnan Province of China as the research site and collected data on typical geological disaster events and the associated hazards that occurred within the study area to construct a corresponding index system for geological disaster assessment. Four methods were used to model and evaluate geological disaster susceptibility. The predictive capabilities of the methods were verified using the receiver operating characteristic(ROC) curve and the success rate curve. Lastly, spatial accuracy validation was introduced to improve the results of the evaluation, which was demonstrated by the spatial receiver operating characteristic(SROC) curve and the spatial success rate(SSR) curve. The results suggest that: 1) these methods are all valid with respect to the SROC and SSR curves, and the spatial accuracy validation method improved their modelling results and accuracy, such that the area under the curve(AUC) values of the ROC curves increased by about 3%–13% and the AUC of the success rate curve values increased by 15%–20%; 2) the evaluation accuracies of LR, SAR, GWR, and SVR were 0.8325, 0.8393, 0.8370 and 0.8539, which proved the four statistical regression methods all have good evaluation capability for geological disaster susceptibility evaluation and the evaluation results of SVR are more reasonable than others; 3) according to the evaluation results of SVR, the central-southern Yunnan Province are the highest sus-ceptibility areas and the lowest susceptibility is mainly located in the central and northern parts of the study area.

Distribution Pattern of and Spatial Correlation Between Traditional Villages and Geological Disasters:A Case Study on Aba Prefecture,Sichuan Province

Identifying the types of disasters and analyzing the distribution pattern of and the spatial correlation between villages and disasters are important prerequisite for the disaster prevention and mitigation of traditional villages.Taking Aba Tibetan and Qiang Autonomous Prefecture as an example and using the tools of kernel density evaluation and spatial statistics,this paper analyzes the distribution pattern of and the spatial correlation between traditional villages and typical geological disasters on the three spatial scales of Aba Prefecture,village agglomeration area,and village administrative area with necessary explanations.It concludes that most of the traditional villages in Aba Prefecture agglomerate in the middle-and high-level alpine gorges and some are clustered at either the border area or the central hinterland of counties;with the increase of maximum seismic intensity and frequency of earthquakes,it appears there is an increase of traditional villages and their trend of agglomeration,which implies an overlap of the areas of dense traditional villages and high-density geological disasters,as well as the synchronous increase of traditional village density and geological disaster density;and the traditional villages in Aba Prefecture are affected by multiple disasters,in particular landslide and debris flow.Finally,the paper discusses the issue of disaster prevention and mitigation in the protection and development planning of traditional villages.

Comparative study of different machine learning models in landslide susceptibility assessment: A case study of Conghua District, Guangzhou, China

Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Conghua District,which is the most prone to landslide disasters in Guangzhou,was selected for landslide susceptibility evaluation.The evaluation factors were selected by using correlation analysis and variance expansion factor method.Applying four machine learning methods namely Logistic Regression(LR),Random Forest(RF),Support Vector Machines(SVM),and Extreme Gradient Boosting(XGB),landslide models were constructed.Comparative analysis and evaluation of the model were conducted through statistical indices and receiver operating characteristic(ROC)curves.The results showed that LR,RF,SVM,and XGB models have good predictive performance for landslide susceptibility,with the area under curve(AUC)values of 0.752,0.965,0.996,and 0.998,respectively.XGB model had the highest predictive ability,followed by RF model,SVM model,and LR model.The frequency ratio(FR)accuracy of LR,RF,SVM,and XGB models was 0.775,0.842,0.759,and 0.822,respectively.RF and XGB models were superior to LR and SVM models,indicating that the integrated algorithm has better predictive ability than a single classification algorithm in regional landslide classification problems.

Analysis of the Heavy Rainfall Process in Mangshi City on August 8, 2023

On August 7,2023,Mangshi City,Dehong Prefecture experienced a local heavy rainstorm,and the geological disaster caused by the heavy rainfall caused casualties and property losses.Based on the real-time observation data of automatic stations,Doppler weather radar detection and meteorological risk warning products,the disaster situation,social impact,forecast and early warning service,causes of heavy precipitation and forecast and early warning inspection were summarized and analyzed.The results show that the heavy rainfall was prominent locally,lasted for a long time and accumulated a large amount of rainfall.There were biases in model products,and it was difficult for forecasters to make subjective corrections in complex terrain.The analysis ideas and focus points of heavy rainfall forecast,the improvement ideas and technical schemes of forecast deviation,and the improvement ideas and suggestions of services were summarized.It provides a reference for the forecast and early warning of severe weather in the future.

Geometrical feature analysis and disaster assessment of the Xinmo landslide based on remote sensing data

At 5:39 am on June 24, 2017, a landslide occurred in the village of Xinmo in Maoxian County, Aba Tibet and Qiang Autonomous Prefecture(Sichuan Province, Southwest China). On June 25, aerial images were acquired from an unmanned aerial vehicle(UAV), and a digital elevation model(DEM) was processed. Landslide geometrical features were then analyzed. These are the front and rear edge elevation, accumulation area and horizontal sliding distance. Then, the volume and the spatial distribution of the thickness of the deposit were calculated from the difference between the DEM available before the landslide, and the UAV-derived DEM collected after the landslide. Also, the disaster was assessed using high-resolution satellite images acquired before the landslide. These include Quick Bird, Pleiades-1 and GF-2 images with spatial resolutions of 0.65 m, 0.70 m, and 0.80 m, respectively, and the aerial images acquired from the UAV after the landslide with a spatial resolution of 0.1 m. According to the analysis, the area of the landslide was 1.62 km2, and the volume of the landslide was 7.70 ± 1.46 million m3. The average thickness of the landslide accumulation was approximately 8 m. The landslide destroyed a total of 103 buildings. The area of destroyed farmlands was 2.53 ha, and the orchard area was reduced by 28.67 ha. A 2-km section of Songpinggou River was blocked and a 2.1-km section of township road No. 104 was buried. Constrained by the terrain conditions, densely populated and more economically developed areas in the upper reaches of the Minjiang River basin are mainly located in the bottom of the valleys. This is a dangerous area regarding landslide, debris flow and flash flood events Therefore, in mountainous, high-risk disaster areas, it is important to carefully select residential sites to avoid a large number of casualties.

Planning and construction of Xiong’an New Area(city of over 5 million people):Contributions of China’s geologists and urban geology

China established Xiong’an New Area in Hebei Province in 2017,which is planned to accommodate about 5 million people,aiming to relieve Beijing City of the functions non-essential to its role as China’s capital and to expedite the coordinated development of the Beijing-Tianjin-Hebei region.From 2017 to 2021,the China Geological Survey(CGS)took the lead in multi-factor urban geological surveys involving space,resources,environments,and disasters according to the general requirements of“global vision,international standards,distinctive Chinese features,and future-oriented goals”in Xiong’an New Area,identifying the engineering geologic conditions and geologic environmental challenges of this area.The achievements also include a 3D engineering geological structure model for the whole area,along with“one city proper and five clusters”,insights into the ecology and the background endowment of natural resources like land,geothermal resources,groundwater,and wetland of the area before engineering construction,a comprehensive monitoring network of resources and environments in the area,and the“Transparent Xiong’an”geological information platform that is open,shared,dynamically updated,and three-dimensionally visualized.China’s geologists and urban geology have played a significant role in the urban planning and construction of Xiong’an New Area,providing whole-process geological solutions for urban planning,construction,operation and management.The future urban construction of Xiong’an New Area will necessitate the theoretical and technical support of earth system science(ESS)from various aspects,and the purpose is to enhance the resilience of the new type of city and to provide support for the green,low-carbon,and sustainable development of this area.

Research on Risk Assessment of City Natural Disaster based on Neural Network

Aiming at the selection of fuzzy AHP and fuzzy DH methods in the previous studies, this paper evaluate the qualitative index system using expert questionnaire, the self-learning BP neural network model to construct the index of system, and complete the establishment of model, in order to avoid the serious subjectivity, and using statistical and measurement methods test the reliability index, analyze the validity of the evaluation index system and completeness. Finally, the paper validate the practicability of the model.

The evaluation of mine geology disasters based on fuzzy mathematics and grey theory

Mine geology disasters include mine water, mine solid waste, apron and slide, ground collapse sink and underground fracture, etc.. The subject was studied in many ways, and fuzzy mathematics was usually used. It may assure the result and distinguish the dangerous rank of different areas. But it has two defects： The first is the result is not very exact, especially the border; The second is it is short of quantity. Fuzzy mathematics and grey theory were used in order to solve the problem. Firstly, mathematical model was constructed by using grey theory, so as to evaluate and forecast the dangerous rank of mining geology disaster in different areas. Then different areas were analyzed and divided by fuzzy mathematics. By doing these, similitude rules are not only studied but also differences are discriminated. Through the practice it can be known that the result is more accurate than before.