Probabilistic seismic and tsunami hazard analysis for design criteria development of a coastal area in the city of Banda Aceh

Both seismic and tsunami hazards design criteria are essential input to the rehabilitation and long-term development of city of Banda Aceh Post Sumatra 2004 (M _w=9.3) disaster. A case study to develop design criteria for future disaster mitigation of the area is presented. The pilot study consists of probabilistic seismic and tsunami hazard analysis. Results of the probabilistic seismic hazard analysis indicates that peak ground acceleration at baserock for 10 and 2% probability of exceedance in 50 years is 0.3 and 0.55 g, respectively. The analysis also provides spectral values at short (T=0.2 s) and long period (T=1.0 s) motions. Some non-linear time-domain earthquake response analyses for soft, medium, and hard site-class were conducted to recommend design response spectra for each site-class. In addition, tsunami inundation maps generated from probabilistic tsunami hazard analysis were developed through tsunami wave propagation analysis and run-up numerical modeling associated with its probability of tsunamigenic earthquake source potential. Both the seismic and tsunami hazard curve and design criteria are recommended as contribution of this study for design criteria, as part of the disaster mitigation effort in the development process of the city. The methodology developed herein could be applied to other seismic and tsunami disaster potential areas.     

Earthquake risk assessment in NE India using deep learning and geospatial analysis

Earthquake prediction is currently the most crucial task required for the probability, hazard, risk mapping, and mitigation purposes. Earthquake prediction attracts the researchers' attention from both academia and industries. Traditionally, the risk assessment approaches have used various traditional and machine learning models. However, deep learning techniques have been rarely tested for earthquake probability mapping. Therefore, this study develops a convolutional neural network (CNN) model for earthquake probability assessment in NE India. Then conducts vulnerability using analytical hierarchy process (AHP), Venn's intersection theory for hazard, and integrated model for risk mapping. A prediction of classification task was performed in which the model predicts magnitudes more than 4 Mw that considers nine indicators. Prediction classification results and intensity variation were then used for probability and hazard mapping, respectively. Finally, earthquake risk map was produced by multiplying hazard, vulnerability, and coping capacity. The vulnerability was prepared by using six vulnerable factors, and the coping capacity was estimated by using the number of hospitals and associated variables, including budget available for disaster management. The CNN model for a probability distribution is a robust technique that provides good accuracy. Results show that CNN is superior to the other algorithms, which completed the classification prediction task with an accuracy of 0.94, precision of 0.98, recall of 0.85, and F1 score of 0.91. These indicators were used for probability mapping, and the total area of hazard (21,412.94 km²), vulnerability (480.98 km²), and risk (34,586.10 km²) was estimated.     

Multi-criteria vulnerability analysis to earthquake hazard of Bucharest, Romania

The expansive infrastructure, along with the high population density, makes cities highly vulnerable to the severe impacts of natural hazards. In the context of an explosive increase in value of the damage caused by natural disasters, the need for evaluating and visualizing the vulnerability of urban areas becomes a necessity in helping practitioners and stakeholders in their decision-making processes. The paper presented is a piece of exploratory research. The overall aim is to develop a spatial vulnerability approach to address earthquake risk, using a semi-quantitative model. The model uses the analytical framework of a spatial GIS-based multi-criteria analysis. For this approach, we have chosen Bucharest, the capital city of Romania, based on its high vulnerability to earthquakes due to a rapid urban growth and the advanced state of decay of the buildings (most of the building stock were built between 1940 and 1977). The spatial result reveals a circular pattern, pinpointing as hot spots the Bucharest historic centre (located on a meadow and river terrace, and with aged building stock) and peripheral areas (isolated from the emergency centers and defined by precarious social and economic conditions). In a sustainable development perspective, the example of Bucharest shows how spatial patterns shape the ??vulnerability profile?? of the city, based on which decision makers could develop proper prediction and mitigation strategies and enhance the resilience of cities against the risks resulting from the earthquake hazard.     

Comparative Risk Assessments for the City of Cologne – Storms, Floods, Earthquakes

In this paper a methodology for a multi-risk assessment of an urban area is introduced and performed for the city of Cologne, Germany, considering the natural hazards windstorm, flooding and earthquake. Moreover, sources of the uncertainty in the analysis and future needs for research are identified. For each peril the following analyses were undertaken: hazard assessment, vulnerability assessment and estimation of losses. To compare the three hazard types on a consistent basis, a common economic assessment of exposed assets was developed. This was used to calculate direct economic losses to buildings and their contents. The perils were compared by risk curves showing the exceedence probability of the estimated losses. In Cologne, most of the losses that occur frequently are due to floods and windstorms. For lower return periods (10–200 years) the risk is dominated by floods. For return periods of more than 200 years the highest damage is caused by earthquakes.     

Site-specific earthquake response study for hazard assessment in Kolkata city,India

The assessment of local site effects on seismic ground motions is of great importance in earthquake engineering practice. Several destructive earthquakes in the past have demonstrated that the amplification of ground motion and associated damage to structures due to local site conditions is a significant consideration in earthquake hazard analysis. A recent paper published in this journal highlights the hazard posed by earthquakes in the megacity of Kolkata in India due to its seismic and geological settings. The seismic hazard assessment study speculates that the deep alluvial deposit in the city may increase the seismic hazard probably due to the amplification of the seismic energies. This paper focuses on the seismic response studies of the various soil strata (i.e. for local subsurface conditions) obtained from various construction sites in the city for predicted earthquake. It is very well recognized that site response studies (a part of seismic microhazard zonation for urban areas) are the first step towards performance-based foundation design or seismic risk analysis and mitigation strategy. One of the problems for carrying out site-specific study in Kolkata is the lack of recorded strong motion data in the city. Hence, this paper outlines a methodology to carry out site-specific study, where no strong motion data or seismic data are available. The methodology uses wavelet-based spectrum compatibility approach to generate synthetic earthquake motions and equivalent linear method for seismic site response analysis. The Mega City of Kolkata has been considered to explain the methodology. Seismic hazard zonation map by the Bureau of Indian Standards classifies the City of Kolkata as moderate seismic zone (Zone III) with a zone factor 0.16. On the other hand, GSHAP(Global Seismic Hazard Assessment Program) map which is based on 10% probability of exceedance in 50 years specifies a maximum peak ground acceleration (PGA) of 1.6 m/s² (0.163 g) for this region. In the present study, the seismic response has been carried out based on GSHAP. The results of the analysis indicate the amplification of ground motion in the range of 4.46–4.82 with the fundamental period ranging from 0.81 to 1.17 s. Furthermore, the maximum spectral accelerations vary in the range of 0.78–0.95 g.     

Validation and development of composite indices for measuring vulnerability to earthquakes using a socio-economic perspective

While many approaches for assessing earthquake risk exist within the literature and practice, it is the dynamic interrelationships between earthquake hazard, physical risk, and the social conditions of populations that are the focal point for disaster risk reduction. Here, the measurement of vulnerability to earthquakes (i.e., characteristics that create the potential for harm or loss) has become a major focus area. However, metrics aimed at measuring vulnerability to earthquakes suffer from several key limitations. For instance, hazard and community context are often ignored, and attempts to validate metrics are largely non-existent. The purpose of this paper is to produce composite indices of the vulnerability of countries to earthquakes within three topical areas: social vulnerability, economic vulnerability, and recovery potential. To improve upon the status quo in indicators development for measuring vulnerability to seismic events, our starting point was to: (1) define a set of indicators that are context specific to earthquakes as defined by the literature; (2) delineate indicators within categorical areas of vulnerability that are easy to understand and could be put into practical use by DRR practitioners; and (3) propose indicators that are validated using historical earthquake impacts. When mapped, the geographic variations in the differential susceptibility of populations and economies to the adverse effects of damaging earthquake impacts become evident, as does differential ability of countries to recover from them. Drivers of this geographic variation include average country debt, the type and density of infrastructure, poverty, governance, and educational attainment, to name just a few.

     

Net earthquake hazard and elements at risk (NEaR) map creation for city of Istanbul via spatial multi-criteria decision analysis

The creation of earthquake hazard maps requires various datasets with selected attenuation relations. Based on the selected attenuation relation, the calculation time varies from half an hour to a couple of days. The length of time needed to create an earthquake hazard map also depends on the resolution of the resulting map. The time gets longer as the resolution of the resulting earthquake hazard map gets higher. The basic form of an attenuation relation requires complex calculation algorithms including geospatial information related to the region of interest. Nowadays, next-generation attenuation (NGA) models are introduced to generate more realistic earthquake hazard maps. However, the more complex the attenuation relation is, the longer time will be required to create a hazard map. This paper offers a new method to create high-resolution earthquake hazard maps, faster than using traditional attenuation relation methods, by using an analytic hierarchy process of spatial multi-criteria decision analysis and geographic information systems. This method has been generated and tested for the city of Istanbul. The resulting maps are compared with the earthquake hazard maps created for the city of Istanbul by using the NGA model of Boore and Atkinson (in Boore–Atkinson NGA ground motion relations for the geometric mean horizontal component of peak and spectral ground motion parameters (trans: Engineering Co, University of California B). Pacific Earthquake Engineering Research Center 2007). A second output of this paper is a map of the elements at risk (EaR) for the population and buildings of Istanbul, and the introduction of a new approach of net elements at risk (NEaR).     

Seismic hazard map of Coimbatore using subsurface fault rupture

This study presents the future seismic hazard map of Coimbatore city, India, by considering rupture phenomenon. Seismotectonic map for Coimbatore has been generated using past earthquakes and seismic sources within 300 km radius around the city. The region experienced a largest earthquake of moment magnitude 6.3 in 1900. Available earthquakes are divided into two categories: one includes events having moment magnitude of 5.0 and above, i.e., damaging earthquakes in the region and the other includes the remaining, i.e., minor earthquakes. Subsurface rupture character of the region has been established by considering the damaging earthquakes and total length of seismic source. Magnitudes of each source are estimated by assuming the subsurface rupture length in terms of percentage of total length of sources and matched with reported earthquake. Estimated magnitudes match well with the reported earthquakes for a RLD of 5.2% of the total length of source. Zone of influence circles is also marked in the seismotectonic map by considering subsurface rupture length of fault associated with these earthquakes. As earthquakes relive strain energy that builds up on faults, it is assumed that all the earthquakes close to damaging earthquake have released the entire strain energy and it would take some time for the rebuilding of strain energy to cause a similar earthquake in the same location/fault. Area free from influence circles has potential for future earthquake, if there is seismogenic source and minor earthquake in the last 20 years. Based on this rupture phenomenon, eight probable locations have been identified and these locations might have the potential for the future earthquakes. Characteristic earthquake moment magnitude (M _w ) of 6.4 is estimated for the seismic study area considering seismic sources close to probable zones and 15% increased regional rupture character. The city is divided into several grid points at spacing of 0.01° and the peak ground acceleration (PGA) due to each probable earthquake is calculated at every grid point in city by using the regional attenuation model. The maximum of all these eight PGAs is taken for each grid point and the final PGA map is arrived. This map is compared to the PGA map developed based on the conventional deterministic seismic hazard analysis (DSHA) approach. The probable future rupture earthquakes gave less PGA than that of DSHA approach. The occurrence of any earthquake may be expected in near future in these eight zones, as these eight places have been experiencing minor earthquakes and are located in well-defined seismogenic sources.     

Changes in coastal land use and the reasons for selecting places to live in Banda Aceh 10 years after the 2004 Indian Ocean tsunami

Ten years after the Indian Ocean tsunami in 2004 and following a long process of rehabilitation and reconstruction, Aceh has finally recovered. After the tsunami, Aceh experienced a dramatic migration of its coastal population away from the city; however, after 10 years, the population has mostly recovered. As new houses have been built and new economic activities commenced in the coastal areas, there is now concern regarding potential future tsunami risks for the city. The initial rehabilitation and reconstruction plan sought to prevent the construction of any new houses 500 m from the coastline; however, this failed to happen. This paper elucidates the reasons why these new coastal communities chose their new housing areas and examines the coastal land use changes around Banda Aceh 10 years after the Indian Ocean tsunami. Questionnaires were distributed to 457 respondents, and multiple logistic regressions were used to examine the reasons for household location selection and whether a possible future tsunami was a deciding factor. To examine the coastal land use changes, a series of aerial images from the Banda Aceh coastal area were digitised. It was found that tsunami history was not a major factor in new household selection; rather, rents and land prices, distance from work, and family connections were the top three reasons motivating households to select new living places. These changes and new settlements have given the city’s disaster management agency the challenge of building more emergency infrastructure in the coastal areas.     

Evaluation of liquefaction potential hazard of Chennai city, India: using geological and geomorphological characteristics

According to the latest UNFA Report on state of world population 2007, unleashing the potential of urban growth by 2030, the urban population will rise to 5 billion or 60?% of the world population. Liquefaction in urban areas is dangerous phenomenon, which cause more damage to buildings and loss of human lives. Chennai, the capital city of the State Tamil Nadu in India, is one of the densely populated cities in the country. The city has experienced moderate magnitude earthquakes in the past and also categorized under moderate seismic hazard as per the Bureau of Indian Standards (BIS in Criteria for earthquake resistant design of structures; Bureau of Indian Standards, New Delhi, 1893 2001). A study has been carried out to evaluate the liquefaction potential of Chennai city using geological and geomorphological characteristics. The subsurface lithology and geomorphological maps were combined in the GIS platform for assessing the liquefaction potential. The liquefaction hazard broadly classified into three categories viz., liquefaction likely, possible and not likely areas. Mainly, the liquefaction likely areas spread along the coastal areas and around the river beds. The rest of the areas are liquefaction not likely and possible. The present map can be used as first-hand information on regional liquefaction potential for the city, and it will be help to the scientists, engineers and planners who are working for future site-specific studies of the city.     

Vulnerability index and capacity spectrum based methods for urban seismic risk evaluation. A comparison

This article contributes to the development and application of two latest-generation methods of seismic risk analysis in urban areas. The first method, namely vulnerability index method (VIM), considers five non-null damage states, defines the action in terms of macroseismic intensity and the seismic quality of the building by means of a vulnerability index. The estimated damage degree is measured by semi-empirical functions. The second method, namely capacity spectrum based method (CSBM), considers four no damage states, defines the seismic action in terms of response spectra and the building vulnerability by means of its capacity spectrum. In order to apply both methods to Barcelona (Spain) and compare the results, a deterministic and a probabilistic hazard scenario with soil effects are used. The deterministic one corresponds to a historic earthquake, while the probabilistic seismic ground motion has a probability of exceedence of 10% in 50 years. Detailed information on the building design has been obtained along years by collecting, arranging, improving, and completing the database of the dwellings of the city. A Geographic Information System (GIS) has been customized allowing storing, analysing, and displaying this large amount of spatial and tabular data of dwellings. The obtained results are highly consistent with the historical and modern evolution of the populated area and show the validity and strength of both methods. Although Barcelona has a low to moderate seismic hazard, its expected seismic risk is significant because of the high vulnerability of its buildings. Cities such as Barcelona, located in a low to moderate seismic hazard region, are usually not aware of the seismic risk. The detailed risk maps obtained offer a great opportunity to guide the decision making in the field of seismic risk prevention and mitigation in Barcelona, and for emergency planning in the city.     

Local seismic hazard assessment in areas of weak to moderate seismicity—case study from Eastern Germany

Generally the seismic hazard of an area of interest is considered independent of time. However, its seismic risk or vulnerability, respectively, increases with the population and developing state of economy of the area. Therefore, many areas of moderate seismic hazard gain increasing importance with respect to seismic hazard and risk analysis. However, these areas mostly have a weak earthquake database, i.e., they are characterised by relative low seismicity and uncertain information concerning historical earthquakes. In a case study for Eastern Thuringia (Germany), acting as example for similar places in the world, seismic hazard is estimated using the probabilistic approach. Because of the lack of earthquakes occurring in the recent past, mainly historical earthquakes have to be used. But for these the actual earthquake sources or active faults, needed for the analysis, are imprecisely known. Therefore, the earthquake locations are represented by areal sources, a common practice. The definition of these sources is performed carefully, because their geometrical shape and size (apart from the earthquake occurrence model) influence the results significantly. Using analysis tools such as density maps of earthquake epicentres, seismic strain and energy release support this. Oversizing of areal sources leads to underestimation of seismic hazard and should therefore be avoided. Large location errors of historical earthquakes on the other hand are represented by several alternative areal sources with final superimposition of the different results. In a very similar way information known from macroseismic observations interpreted as source rather than as site effects are taken into account in order to achieve a seismic hazard assessment as realistic as possible. In very local cases the meaning of source effects exceeds those of site effects very likely. The influence of attenuation parameter variations on the result of estimated local seismic hazard is relatively low. Generally, the results obtained by the seismic hazard assessment coincide well with macroseismic observations from the thoroughly investigated largest earthquake in the region.     

Mapping seismic risk: the current crisis

The seismic risks to which populations are exposed should be estimated reliably for mitigation and preparation of response to disastrous earthquakes. Three parameters need to be known: Population numbers, properties of the built environment, and the seismic hazard. If we focus on large cities, we can say that at least one of these is known satisfactorily, namely the population, but not the other two. In the developing world, the numbers of buildings in a city are known only approximately, their distribution into building types (resistance to shaking) has to be assumed, and the distribution of types throughout the city is unknown. Recent verification of the world seismic hazard map has shown that it is grossly misleading: Instrumental measurements of accelerations due to six earthquakes were about three times larger, on average, than the maximum likely accelerations shown on the map; the macroseismic intensities reported for the last 60 earthquakes with M ≥ 7.5 were all significantly larger than expected, based on the hazard map (by 2.3 intensity units for the 12 deadliest earthquakes); and calculations of losses of life based on the hazard map underestimate the losses sustained in the 12 recent earthquakes with more than 1,000 fatalities by two to three orders of magnitude. This means that the seismic risk in most of the approximately 1,000 large cities at risk in the developing world is unknown. To remedy this intolerable situation, models for the built environment in cities need to be constructed, using cost-effective analyses of satellite images, and worst case scenario estimates of the losses in case of the nearest maximum credible earthquake.     

Earthquake risk assessment in urban fabrics based on physical,socioeconomic and response capacity parameters (a case study: Tehran city)

Determination of the priorities for improvement of vulnerable urban fabrics based on a comprehensive assessment is among the main desires of local governments in earthquake-prone countries like Iran. However, in most countries, the comprehensive and absolute estimation of seismic risk is not possible due to shortages of the required data. In this paper, a new method is proposed for estimation of the risk through combination of hazard, vulnerability and response capacity indicators. Also, new evaluation methods based on relative scheme are presented for simple quantification of indicators in urban areas suffering from limited or insufficient database. For this purpose, important vulnerability parameters at urban areas are classified into physical, human life and socioeconomic groups. New hazard factors are also defined to evaluate the risk through combination of each vulnerability indicator and its directly related hazard factor. In addition, the capacity of response activities is accounted for in the model using planning, resource, accessibility and evacuation capacity indicators. The post-earthquake reduction of response capacity is also measured by means of reduction factors. Then, total relative seismic risk index is defined and calculated at each urban division (or zone) by weighted combination of the mentioned risk and response capacity indicators. This index represents the state of the risk in each zone in comparison with the others. The proposed method is applied to assess the earthquake risk at 22 municipal districts of Tehran. The results show that physical, human life and overall risk indices in district 15 of the city are considerably greater than the others. Meanwhile, in socioeconomic aspects, district 6 has the highest risk. Also, the analysis of the results demonstrates the major contribution of the response capacity term to determine the mitigation priorities. Finally, the results are compared with JICA (2000), using the same data, to show the efficiency of the proposed model. It is shown that the introduced method can significantly improve the results of the risk estimation and mitigation priorities.     

Earthquake vulnerability and seismic risk assessment of urban areas in high seismic regions: application to Chania City,Crete Island,Greece

The earthquake vulnerability and the seismic risk assessment for the urban center of Chania in the island of Crete is approached through the development of a GIS-based application that takes into consideration the structural and geological domain of the region. Considering a localized model, the various structural and geomorphologic attributes of the region were assigned specific weights of significance that allowed the creation of a modular application that was tested for the city of Chania, and it was verified based on the recent seismic activity of the area. The proposed risk map and model can become a significant tool for confronting crises resulting from future earthquake incidences.     

海啸灾害后印度尼西亚班达阿齐市的土地覆盖变化与海岸带区域规划

2004年12月26日，由于欧亚板块的碰撞，40年以来最大的地震灾害发生在印度洋。地震诱发的海啸影响到Nangroe Aceh Darussalam省的许多城市，包括省会城市班达阿齐。在这地区共有超过12万人死亡，100万人无家可归。基于遥感数据的分析表明，有12万亩的土地受到了灾害。在班达阿齐市，鱼塘、住宅用地和保护区的变化是这一地区最显著的土地利用/覆盖变化，受灾前后这些用地类型的面积相应的变化了61.5%、57.8% 和77.6%。目前，印度尼西亚中央政府正在计划一个新的海岸带土地利用规划，在原来密集的海岸带建立一个缓冲区（约距海岸带2 km）。政府已经要求许多海岸带的社区代表与非政府组织参与到决策的过程中。 为了选择并采取最佳的土地利用方式，海啸灾害后的海岸带规划应该包括一些重要的基本要素。本研究主要关注作为该省社会经济活动中心的班达阿齐市。检测了由于海啸灾害造成的土地利用/覆盖变化（包括物理破坏），特别是农业用地和居住区用地的变化，并且分析了受灾村落的不同类型及灾害对社会经济活动造成的影响。此外，还为政府以及当地居民在灾后的规划中选择更为可持续的空间布局方案提出了建议。     

Ground motion studies for microzonation in Iran

An important step in effectively reducing seismic risk and the vulnerability of a city located in an earthquake prone area is to conduct a ground motion microzonation study for the desired return period. The International Institute of Earthquake Engineering and Seismology (IIEES) initiated a number of seismic microzonation projects for Iran. This paper presents the steps followed by IIEES in ground motion microzonation. IIEES performs both probabilistic and deterministic seismic hazard analysis. IIEES uses his own fault map for seismotectonic studies and develops modulus and damping curves for the soils in the study area. The experience of ground motion microzonation shows that in almost all cases, the estimated 475-year peak ground acceleration (PGA) values are higher than the PGA proposed by the Iranian seismic code. Although ground motion microzonation in Iran has some shortcomings, IIEES is making new improvement. This includes development in deterministic seismic hazard analysis, two-dimensional and three-dimensional modelling of basin and topographical effects, using microtremor measurements to find shear-wave velocity profiles in high-density urban areas and providing maps for spectral acceleration in the study area.     

A New Probabilistic Seismic Hazard Analysis for the Vrancea (Romania) Seismogenic Zone

In this paper we apply a probabilistic methodology to map specific seismic hazard induced by the Vrancea Seismogenic Zone, which represents the uttermost earthquake danger to Romania as well as its surroundings. The procedure is especially suitable for the estimation of seismic hazard at an individual site, and seismic hazard maps can be created by applying it repeatedly to grid points covering larger areas. It allows the use of earthquake catalogues with incompletely reported historical and complete instrumental parts. When applying themethodology, special attention was given to the effect of hypocentral depth and the variation of attenuation according to azimuth. Hazard maps specifying a 10% chance of exceedance of the given peak ground acceleration value for an exposure time of 50 years were prepared for three different characteristic depths of earthquakes in the Vrancea area. These maps represent a new realistic contribution to the mitigation of the earthquake risk caused by the Vrancea Seismogenic Zone in terms of: (1) input data (consistent, reliable, and the most complete earthquake catalogue), (2) appropriate and specific attenuation relationships (considering both azimuthal and depth effects); and (3) a new and versatile methodology.     

Tsunami vulnerability assessment in urban areas using numerical model and GIS

Natural disasters can neither be predicted nor prevented. Urban areas with a high population density coupled with the construction of man-made structures are subjected to greater levels of risk to life and property in the event of natural hazards. One of the major and densely populated urban areas in the east coast of India is the city of Chennai (Madras), which was severely affected by the 2004 Tsunami, and mitigation efforts were severely dampened due to the non-availability of data on the vulnerability on the Chennai coast to tsunami hazard. Chennai is prone to coastal hazards and hence has hazard maps on its earth-quake prone areas, cyclone prone areas and flood prone areas but no information on areas vulnerable to tsunamis. Hence, mapping has to be done of the areas where the tsunami of December 2004 had directly hit and flooded the coastal areas in Chennai in order to develop tsunami vulnerability map for coastal Chennai. The objective of this study is to develop a GIS-based tsunami vulnerability map for Chennai by using a numerical model of tsunami propagation together with documented observations and field measurements of the evidence left behind by the tsunami in December 2004. World-renowned and the second-longest tourist beach in the world “Marina” present in this region witnessed maximum death toll due to its flat topography, resulting in an inundation of about 300 m landward with high flow velocity of the order of 2 m/s.     

城市泥石流风险评价探讨

探讨了城市泥石流风险评价的系统方法,该方法包括泥石流扇形地危险区划、城市易损性分析和城市泥石流风险评价三个主要内容。泥石流堆积扇危险区划是基于数值模拟计算出的泥深和流速分布图进行叠合完成的。以美国高分辨率的“快鸟”卫星影像为数据源,完成了研究区的城市土地覆盖类型遥感解译,在此基础上完成了城市泥石流易损性分析,应用地理信息系统提供的统计和分析工具,完成了研究区泥石流风险评价。该风险区划图可用于指导对泥石流易泛区的不同风险地带的土地利用进行规划和决策,从而达到规避和减轻灾害的目的,也为生活在泥石流危险区的城市居民提供有关灾害风险信息,以作避难和灾害防治的依据。