Analysis of debris flow control effect and hazard assessment in Xinqiao Gully,Wenchuan M_(s)8.0 earthquake area based on numerical simulation

Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the effectiveness of the debris flow control project and evaluated the debris flow hazards.Through field investigation and numerical simulation methods,the indicators of flow intensity reduction rate and storage capacity fullness were proposed to quantify the effectiveness of the engineering measures in the debris flow event.The simulation results show that the debris flow control project reduced the flow intensity by41.05%to 64.61%.The storage capacity of the dam decreases gradually from upstream to the mouth of the gully,thus effectively intercepting and controlling the debris flow.By evaluating the debris flow of different recurrence intervals,further measures are recommended for managing debris flow events.

Application of logistic regression model for hazard assessment of landslides caused by the 2012 Yiliang Ms 5.7 earthquake in Yunnan Province,China

Accurate assessment of seismic landslides hazard is a prerequisite and foundation for postdisaster relief of earthquakes.An Ms 5.7 earthquake occurring on September 7,2012,in Yiliang County,Yunnan Province,China,triggered hundreds of landslides.To explore the characteristics of coseismic landslides caused by this moderate-strong earthquake and their significance in predicting seismic landslides regionally,this study uses an artificial visual interpretation method based on a planet image with 5-m resolution to obtain the information of the coseismic landslides and establishes a coseismic landslide database containing data on 232 landslides.Nine influencing factors of landslides were selected for this study:elevation,relative elevation,slope angle,aspect,slope position,distance to river system,distance to faults,strata,and peak ground acceleration.The real probability of coseismic landslide occurrence is calculated by combining the Bayesian probability and logistic regression model.Based on the coseismic landslides,the probabilities of landslide occurrence under different peak ground acceleration are predicted using a logistic regression model.Finally,the model established in this paper is used to calculate the landslide probability of the Ludian Ms 6.5 earthquake that occurred in August 2014,78.9 km away from the macro-epicenter of the Yiliang earthquake.The probability is verified by the real coseismic landslides of this earthquake,which confirms the reliability of the method presented in this paper.This study proves that the model established according to the seismic landslides triggered by one earthquake has a good effect on the seismic landslides hazard assessment of similar magnitude,and can provide a reference for seismic landslides prediction of moderate-strong earthquakes in this region.

Evolution of Coulomb failure stress in Sulaiman Lobe,Pakistan,and its implications for seismic hazard assessment

In this research work,we present the evolution of Coulomb failure stress(CFS)in the Sulaiman Lobe and its implications for seismic hazard assessment.The Chaman transform fault,~1,000 km long,is the major active fault that marks the western boundary between Pakistan and Afghanistan on the Indian Plate.To date,few studies have been conducted to unveil the interactions among earthquakes and the implications of these interactions for seismic hazard assessment in the region.We thoroughly investigated the published and online catalog to construct a sequence of major earthquakes that occurred in this region during the past.The final earthquake sequence was composed of 15 earthquakes of M_(w)≥6.0,beginning with the 1888 earthquake.We used the stress-triggering theory to numerically simulate the evolution of CFS caused by these earthquakes.The numerical results revealed that 8 out of 15earthquakes were triggered by the preceding earthquakes.The earthquakes in 1908,1910,1935,1966,and 1997 were rather independent earthquakes in this sequence.Although the epicenters of the 1975a and 1975b earthquakes were in the stress shadow zone,the partial rupture segments of both these earthquakes were in high-CFS regions.The CFS induced by the 1935 earthquake was notable,as it later triggered the 2008 doublet.Moreover,our results revealed that the northern segment of the Chaman Fault,the southern segment of the Ghazaband Fault,and the northwestern segment of the Urghargai Fault demonstrated a high change in CFS that could trigger seismicity in these regions.The necessary arrangements must therefore be made to mitigate any possible seismic hazards in the region.

Investigation and Hazard Assessment of Invasive Alien Plants on the Campus of Tongren University

[Objectives]The paper was to investigate and assess the species,distribution and hazard status of invasive alien plants on the campus of Tongren University.[Methods]A survey was conducted using line survey method,and the risk assessment index system of invasive alien plants was established by analytic hierarchy process(AHP).[Results]There were 11 species of invasive alien plants on the campus of Tongren University,belonging to 8 genera and 5 families.There were 6 species of invasive alien plants belonging to Asteraceae,accounting for 54.55%of the total.In terms of the origin of invasive plants,most of them were native to North America and Europe,accounting for 27.27%of the total.In terms of harmful level,there were no high-risk invasive plants on the campus of Tongren University,but Alternanthera philoxeroides had the highest score and was the most harmful.[Conclusions]The present situation of alien plant invasion on the campus of Tongren University is closely related to the ecological environment of the campus.It is suggested to strengthen the management of campus plants,focus on the prevention and control of A.philoxeroides,and carry out regular investigation of invasive alien plants on campus to ensure the ecological safety of the campus.

A Hazard Assessment Method for Potential Earthquake-Induced Landslides – A Case Study in Huaxian County, Shaanxi Province

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.

Debris Flow Hazard Assessment Based on Support Vector Machine

Seven factors, including the maximum volume of once flow , occurrence frequency of debris flow , watershed area , main channel length , watershed relative height difference , valley incision density and the length ratio of sediment supplement are chosen as evaluation factors of debris flow hazard degree. Using support vector machine （SVM） theory, we selected 259 basic data of 37 debris flow channels in Yunnan Province as learning samples in this study. We create a debris flow hazard assessment model based on SVM. The model was validated though instance applications and showed encouraging results.

Probabilistic seismic landslide hazard assessment: a case study in Tianshui, Northwest China

Probabilistic analysis in the field of seismic landslide hazard assessment is often based on an estimate of uncertainties of geological, geotechnical,geomorphological and seismological parameters.However, real situations are very complex and thus uncertainties of some parameters such as water content conditions and critical displacement are difficult to describe with accurate mathematical models. In this study, we present a probabilistic methodology based on the probabilistic seismic hazard analysis method and the Newmark’s displacement model. The Tianshui seismic zone(105°00′-106°00′ E, 34°20′-34°40′ N) in the northeastern Tibetan Plateau were used as an example. Arias intensity with three standard probabilities of exceedance(63%, 10%, and 2% in 50 years) in accordance with building design provisions were used to compute Newmark displacements by incorporating the effects of topographic amplification.Probable scenarios of water content condition were considered and three water content conditions(dry,wet and saturated) were adopted to simulate the effect of pore-water on slope. The influence of 5 cm and 10 cm critical displacements were investigated in order to analyze the sensitivity of critical displacement to the probabilities of earthquake-induced landslide occurrence. The results show that water content in particular, have a great influence on the distribution of high seismic landslide hazard areas. Generally, the dry coverage analysis represents a lower bound for susceptibility and hazard assessment, and the saturated coverage analysis represents an upper bound to some extent. Moreover, high seismic landslide hazard areas are also influenced by the critical displacements. The slope failure probabilities during future earthquakes with critical displacements of 5 cm can increase by a factor of 1.2 to 2.3 as compared to that of 10 cm. It suggests that more efforts are required in order to obtain reasonable threshold values for slope failure. Considering the probable scenarios of water content condition which is varied with seasons, seismic landslide hazard assessments are carried out for frequent, occasional and rare earthquake occurrences in the Tianshui region, which can provide a valuable reference for landslide hazard management and infrastructure design in mountainous seismic zones.

Seismic hazard assessment of the Three Gorges Project

Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismieity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earth- quakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types： Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock （terrane） slip earthquakes, all of which are related to the lithology, structure, and tectonics of near- surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below Ms2.0. Therefore, the intensity of the earth- quakes remained at a low level. On November 22, 2008, a magnitude 4.1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-in- duced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.

Probabilistic seismic hazard assessment of Kazakhstan and Almaty city in peak ground accelerations

As for many post-soviet countries, Kazakhstan’s building code for seismic design was based on a deterministic approach. Recently, Kazakhstan seismologists are engaged to adapt the PSHA(probabilistic hazard assessment) procedure to the large amount of available geological, geophysical and tectonic Kazakh data and to meet standard requirements for the Eurocode 8. The new procedure has been used within National projects to develop the Probabilistic GSZ(General Seismic Zoning) maps of the Kazakhstan territory and the SMZ(Probabilistic Seismic Microzoning) maps of Almaty city. They agree with the seismic design principles of Eurocode 8 and are expressed in terms of not only seismic intensity,but also engineering parameters(peak ground acceleration PGA). The whole packet of maps has been developed by the Institute of Seismology, together with other Kazakhstan Institutions. Our group was responsible for making analysis in PGA. The GSZ maps and hazard assessment maps for SMZ in terms of PGA for return periods 475 and 2475 years are considered in the article.

Seismic Hazard Assessment of District Mansehra,Khyber Pakhtoonkhawa,Pakistan

The site of Mansehra is located seismically in an active regime, known as the Crystalline Nappe Zone and Hazara-Kashmir Syntaxis in NW Himalayas, Pakistan. Seismic Hazard Assessment （SHA） for the site has been carried out by considering the earthquake source zones, selection of appropriate attenuation equations, near fault effects and maximum potential magnitude estimation. The Mansehra Thrust, Oghi Fault, Banna Thrust, Balakot Shear Zone, Main Boundary Thrust, Panjal Thrust, Jhelum Fault and Muzaffarabad Fault and, further to the south, the Sanghargali, Nathiagali, and Thandiani Thrusts are the most critical tectonic features within the 50 km radius of Mansehra. Using the available instrumental seismological data from 1904 to 2007, SHA has been carried out. Other reactivated critical tectonic features in the area have been investigated. Among them the Balakot-Bagh fault, with the fault length of 120 km from Balakot to Poonch, has been considered as the most critical tectonic feature on the basis of geological/structural/seismological data. The potential earthquake of maximum magnitude 7.8 has been assigned to the Balakot-Bagh fault using four regression relations. The peak ground acceleration value of 0.25 g （10% probability of exceedance for 50 years） and 0.5 g has been calculated with the help of the attenuation equation using probabilistic and deterministic approaches.

Quantitative hazard assessment system(Has-Q) for open pit mine slopes

Rock slope hazard assessment is an important part of risk analysis for open pit mines.The main parameters that can lead to rock slope failures are the parameters traditionally used in geomechanical classifications,the slope geometrical parameters and external factors like rainfall and blasting.This paper presents a methodology for a hazard assessment system for open pit mine slopes based on 88 cases collated around the world using principal components analysis,discriminant analysis and confidence ellipses.The historical cases used in this study included copper,gold,iron,diamond,lead and zinc,platinum and claystone mines.The variables used in the assessment methodology are uniaxial compressive strength of intact rock;spacing,persistence,opening,roughness,infilling and orientation of the main discontinuity set;weathering of the rock mass;groundwater;blasting method;and height and inclination of the pit.While principal component analysis was used to quantify the data,the discriminant analysis was used to establish a rule to classify new slopes about its stability condition.To provide a practical hazard assessment system,confidence ellipses were used to propose a hazard graph and generate the HAS-Q.The discriminant rule developed in this research has a high discrimination capacity with an error rate of 11.36%.

Seismic Hazard Assessment in the Boundary Region of Indo-China:First Phase of Implementation of the Global Seismic Hazard Assessment Program (GSHAP) in Continental Asia

The primary goal of the demonstration project endorsed by the Scientific and Technical Committee for IDNDR in 1992 is to ensure that national agencies are able to assess seismic hazard in a regionally coordinated fashion by using advanced methods.China,as a Regional Center of Central Southern Asia,has contacted with countries of the region to realistically practice seismic hazard assessments of Continental Asia.A test area located in the collision boundary between the Indian and Eurasian plates was chosen to examine the seismic hazard assessment approach in the regional coordinates.The seismotectonics and three versions of seismic sources of the test area are described in this paper and under the Global Seismic Hazard Assessment Program(GSHAP),guidelines an earthquake catalogue of the test area was assembled.Because of the incompleteness of earthquake data in different countries,we adopt different time windows for different magnitude intervals in order to obtain the seismicity parameters of sources.By

Comprehensive Studies of Seismic Forecast and Seismic Hazard Assessment in Armenia, Current State and Prospects

The study of geophysical processes in different layers of the Earth,seismic hazard assessment,earthquake prediction,etc.are topical fundamental and applied problems.The development of a modern adequate methodology for assessing seismic hazards,operational forecasting of earthquakes.

On unified analysis of uncertainty in seismic hazard assessment

In this paper, firstly the current analysis methods of uncertainties in seismic hazard assessment (SHA) are systematically reviewed, and the existing problems are pointed out. At the same time, it is proposed that the uncertainties can be divided into three kinds, namely, randomness, fuzziness and incompleteness of knowledge, and they can be treated in a unified way. Then, based on marked point process theory, a general equation for SHA is obtained, and a general equation for uncertainty analysis is also given on the basis of total probability theorem. Finally, the relationship between the proposed analysis method with those currently used both at home and abroad is discussed. The analysis shows that they are just the special case of the proposed method.

Automated machine learning for rainfall-induced landslide hazard mapping in Luhe County of Guangdong Province,China

Landslide hazard mapping is essential for regional landslide hazard management.The main objective of this study is to construct a rainfall-induced landslide hazard map of Luhe County,China based on an automated machine learning framework(AutoGluon).A total of 2241 landslides were identified from satellite images before and after the rainfall event,and 10 impact factors including elevation,slope,aspect,normalized difference vegetation index(NDVI),topographic wetness index(TWI),lithology,land cover,distance to roads,distance to rivers,and rainfall were selected as indicators.The WeightedEnsemble model,which is an ensemble of 13 basic machine learning models weighted together,was used to output the landslide hazard assessment results.The results indicate that landslides mainly occurred in the central part of the study area,especially in Hetian and Shanghu.Totally 102.44 s were spent to train all the models,and the ensemble model WeightedEnsemble has an Area Under the Curve(AUC)value of92.36%in the test set.In addition,14.95%of the study area was determined to be at very high hazard,with a landslide density of 12.02 per square kilometer.This study serves as a significant reference for the prevention and mitigation of geological hazards and land use planning in Luhe County.

Application of Hazard Vulnerability Analysis Based on Kaiser Model in Neonatal Breast Milk Management

Objective:To analyze the existing risks in breast milk management at the neonatal department and provide corresponding countermeasures.Methods:22 risk events were identified in 7 risk links in the process of bottle-feeding of breast milk.Hazard Vulnerability Analysis based on the Kaiser model was applied to investigate and evaluate the risk events.Results:High-risk events include breast milk quality inspection,hand hygiene during collection,disinfection of collectors,cold chain management,hand hygiene during the reception,breast milk closed-loop management,and post-collection disposal.Root cause analysis of high-risk events was conducted and breast milk management strategies outside the hospital and within the neonatal department were proposed.Conclusion:Hazard Vulnerability Analysis based on the Kaiser model can identify and assess neonatal breast milk management risks effectively,which helps improve the management of neonatal breast milk.It is conducive to the safe development and promotion of bottle feeding of breast milk for neonates,ensuring the quality of medical services and the safety of children.

A comprehensive geomechanical method for the assessment of rockburst hazards in underground mining

Rockburst hazard in mining industry all over the world is one of the most severe hazards. It is becoming increasingly common because of the ever-growing depths of mining operations accompanied by the increasing strength of rocks. One of the most difficult issues is to predict this hazard before the mining operations, whether geophysical investigations have been conducted or not. Polish experience in this field shows that in such cases an effective solution can be the geomechanical method. Therefore, extensive studies on rockburst hazard should focus on three main aspects:(1) rock mass and rock(and coal)predisposition to rockburst–laboratory tests and empirical analyses based on lithology,(2) identification of the potential places with stress and elastic energy concentration in the rock mass within the area planned for exploitation, and(3) the assessment of the impact of mining tremors on the surface. This preliminary geomechanical analysis assesses the propensity of the rock mass to dynamic breakage and provides quantitatively the level of rockburst hazard. The paper presents Polish experience in rockburst hazard assessment with the use of geomechanical method, as well as some solutions and examples of such analyses.

A Probabilistic Liquefaction Hazard Assessment for Urban Regions Based on Dynamics Analysis Considering Soil Uncertainties

Earthquake induced liquefaction is one of the main geo-disasters threating urban regions, which not only causes direct damages to buildings, but also delays both real-time disaster relief actions and reconstruction activities. It is thus important to assess liquefaction hazard of urban regions effectively and efficiently for disaster prevention and mitigation. Conventional assessment approaches rely on engineering indices such as the factor of safety(FS) against liquefaction, which cannot take into account directly the uncertainties of soils. In contrast, a physics simulation-based approach, by solving soil dynamics problems coupled with excess pore water pressure(EPWP) it is possible to model the uncertainties directly via Monte Carlo simulations. In this study, we demonstrate the capability of such an approach for assessing an urban region with over 10 000 sites. The permeability parameters are assumed to follow a base-10-lognormal distribution among 100 model analyses for each site. A dynamic simulation is conducted for each model analysis to obtain the EPWP results. Based on over 1 million EPWP analysis models, we obtained a probabilistic liquefaction assessment. Empowered by high performance computing, we present for the first time a probabilistic liquefaction hazard assessment for urban regions based on dynamics analysis, which consider soil uncertainties.

Application and discussion of statistical seismology in probabilistic seismic hazard assessment studies

Earthquakes are one of the natural disasters that pose a major threat to human lives and property. Earthquake prediction propels the construction and development of modern seismology;however, current deterministic earthquake prediction is limited by numerous difficulties. Identifying the temporal and spatial statistical characteristics of earthquake occurrences and constructing earthquake risk statistical prediction models have become significant;particularly for evaluating earthquake risks and addressing seismic planning requirements such as the design of cities and lifeline projects based on the obtained insight. Since the 21 st century, the occurrence of a series of strong earthquakes represented by the Wenchuan M8 earthquake in 2008 in certain low-risk prediction areas has caused seismologists to reflect on traditional seismic hazard assessment globally. This article briefly reviews the development of statistical seismology, emphatically analyzes the research results and existing problems of statistical seismology in seismic hazard assessment, and discusses the direction of its development. The analysis shows that the seismic hazard assessment based on modern earthquake catalogues in most regions should be effective. Particularly, the application of seismic hazard assessment based on ETAS(epidemic type aftershock sequence)should be the easiest and most effective method for the compilation of seismic hazard maps in large urban agglomeration areas and low seismic hazard areas with thick sedimentary zones.

Potential seismic landslide hazard and engineering effect in the Ya’an-Linzhi section of the Sichuan-Tibet transportation corridor, China

The Sichuan-Tibet transportation corridor is located at the eastern margin of the Qinghai-Tibet Plateau,where the complex topography and geological conditions,developed geo-hazards have severely restricted the planning and construction of major projects.For the long-term prevention and early control of regional seismic landslides,based on analyzing seismic landslide characteristics,the Newmark model was used to carry out the potential seismic landslide hazard assessment with a 50-year beyond probability 10%.The results show that the high seismic landslide hazard is mainly distributed along large active tectonic belts and deep-cut river canyons,and are significantly affected by the active tectonics.The low seismic landslide hazard is mainly distributed in the flat terrain such as the Quaternary basins,broad river valleys,and plateau planation planes.The major east-west linear projects mainly pass through five areas with high seismic landslide hazard:Luding-Kangding section,Yajiang-Xinlong(Yalong river)section,Batang-Baiyu(Jinsha river)section,Basu(Nujiang river)section,and Bomi-Linzhi(eastern Himalaya syntaxis)section.The seismic action of the Bomi-Linzhi section can also induce high-risk geo-hazard chains such as the high-level glacial lake breaks and glacial debris flows.The early prevention of seismic landslides should be strengthened in the areas with high seismic landslide hazard.