Rapid evaluation of an indicator of seismic vulnerability in small urban nuclei

The expected fraction of buildings lost in the event of an earthquake of a given intensity can be considered as a useful indicator of the seismic vulnerability of a small urban nucleus and can be used for the evaluation of seismic risk on a regional scale. This work describes a procedure for quantifying this indicator through data obtained from the buildings which constitute the nucleus during rapid on-site surveys. The knowledge on which the procedure is based is that given by the observed vulnerability of old Italian centres.     

A new hybrid procedure for the definition of seismic vulnerability in Mediterranean cross-border urban areas

Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called “hybrid.” Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model.

     

A new hybrid procedure for the definition of seismic vulnerability in Mediterranean cross-border urban areas

Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called “hybrid.” Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model.     

Experimental vulnerability curves for the residential buildings of Iran

Iran is one of the most seismically active countries of the world located on the Alpine-Himalayan earthquake belt. More than 180,000 people were killed due to earthquakes in Iran during the last five decades. Considering the fact that most Iranians live in masonry and non-engineered houses, having a comprehensive program for decreasing the vulnerability of society holds considerable importance. For this reason, loss estimation should be done before an earthquake strikes to prepare proper information for designing and selection of emergency plans and the retrofitting strategies prior to occurrence of earthquake. The loss estimation process consists of two principal steps of hazard analysis and vulnerability assessment. After identifying the earthquake hazard, the first step is to evaluate the vulnerability of residential buildings and lifelines and also the social and economic impacts of the earthquake scenarios. Among these, residential buildings have specific importance, because their destruction will disturb the daily life and result in casualties. Consequently, the vulnerability assessment of the buildings in Iran is important to identify the weak points in the built environment structure. The aim of this research is to prepare vulnerability curves for the residential buildings of Iran to provide a proper base for estimating probable damage features by future earthquakes. The estimation may contribute fundamentally for better seismic performance of Iranian societies. After a brief review of the vulnerability assessment methods in Iran and other countries, through the use of the European Macroseismic method, a model for evaluating the vulnerability of the Iranian buildings is proposed. This method allows the vulnerability assessment for numerous sets of buildings by defining the vulnerability curves for each building type based on the damage observations of previous earthquakes. For defining the vulnerability curves, a building typology classification is presented in this article, which is representative of Iranian building characteristics. The hazard is described in terms of the macroseismic intensity and the EMS-98 damage grades have been considered for classifying the physical damage to the buildings. The calculated vulnerability indexes and vulnerability curves show that for engineered houses there is not any notable difference between the vulnerability of Iranian and Risk-UE building types. For the non-engineered houses, the vulnerability index of brick and steel structures is less than the corresponding values of the other unreinforced masonry buildings of Iran. The vulnerability index of unreinforced and masonry buildings of Iran are larger than the values of the similar types in Risk-UE and so the Iranian buildings are more vulnerable in this regard.     

Modeling a spatiotemporal distribution of stranded people returning home on foot in the aftermath of a large-scale earthquake

On the day of the Tohoku-Pacific Ocean Earthquake (2011), all rail services in the Tokyo Metropolitan area were paralyzed, amid substantial confusion. Consequently, over 3 million persons were unable to return home on that day. Some, unable to contact their families, felt uneasy and set out to return home on foot. Main roads were seriously congested with cars and people, and the use of emergency vehicles was also obstructed. In this paper, we construct several models that describe decision-making and behavior of individuals attempting to reach home on foot in the wake of a devastating earthquake. The proposed models are calibrated using data taken from questionnaire surveys and person-trip surveys, addressed to occupants of the Tokyo Metropolitan area. We attempt to simulate the movement of individuals having decided to return home on foot and demonstrate the spatiotemporal distribution of those who might be exposed to city fires on their way home in the context of such an event.     

基于压力?状态?响应模型框架的城市地震综合易损性评价

为了科学评价城市地震灾害状况,降低城市易损性,基于压力-状态-响应模型框架,构建城市地震综合易损性评价指标体系,其中压力类、状态类、响应类指标分别为7、13、8项。应用熵权法确定了各评价指标的权重,提出基于云模型的城市综合易损性评价模型,并运用雷达图分析法实现城市内各个区综合易损性的相对高低。应用上述方法,对兰州市中心城区进行了震害综合易损性评价,结果表明:兰州市综合易损性等级偏向Ⅲ级,易损性中等,其中红古、安宁区的易损性程度较高,城关、七里河易损性程度较低;经济因素对各区域的易损性影响较大,通过对易损区域加强管理建设,提高城市的防震减灾能力。     

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.

     

Unusually low seismic activity in the focal region of the great Kanto earthquake of 1923

The epicenters of earthquakes which occurred in the vicinity of Tokyo during the period 1926–1967 have been plotted by an IBM 360/40 computer at the Earthquake Prediction Observation Center. As a result, a seismically quiescent area is found to the south of Tokyo. The area coincides with the shallower part of the focal plane of the great Kanto earthquake of 1923 as obtained from the analyses of seismological and geodetic data. In historical times, many large earthquakes having a magnitude of 7.0 or greater took place in this area. If it is assumed that the strain energy has been constantly accumulated in this area, an energy potentially equivalent to that of a large earthquake of which the magnitude exceeds 7.7 seems to be stored in the crust there.     

Long-period ground motion in the epicentral area of major earthquakes

In view of the potential importance of long-period ground motion in the design of large structures, near-field ground displacement is computed by the elastic dislocation theory for several earthquake fault models. The validity of such computations is confirmed by comparing the computed seismogram with the observed long-period seismogram of the 1923 Kanto earthquake. The ground motions are computed for three hypothetical earthquakes, a hypothetical Kanto earthquake, Tokai earthquake and Nemuro-Oki earthquake. The location and the nature of the faulting of these earthquakes are predicted by plate tectonics and precise earthquake mechanism studies. Major conclusions are: Tokyo may suffer, in the hypothetical Kanto earthquake, ground motions about half as large as those experienced in the 1923 Kanto earthquake; Hamamatsu, a large city on the Tokai coast, may experience in the hypothetical Tokai earthquake ground motions which are as large as, or even larger than, those experienced in the epicentral area of the 1923 Kanto earthquake; the hypothetical Nemuro-Oki earthquake may cause ground motions as large as those experienced in the 1968 Tokachi-Oki earthquake on the coastal cities in Hokkaido.     

Management and application of Geotechnical Data: The Geotechnical Data Information System of the Tokyo Metropolitan Government

In the Tokyo metropolis many geological surveys are carried out in conjunction with building construction work and urban base improvement undertakings. Furthermore, the Institute of Civil Engineering (ICE) of the Tokyo Metropolitan Government (TMG) has been conducting surveys on urban geology, land subsidence, and geodetics. Thus, ICE of TMG keeps a lot of geological data. In order to plan for a more effective use of these data, the Geotechnical Data Information System of Tokyo Metropolitan Government was organized in 1985, and since 1986, it has become fully implemented.This Geotechnical Data Information System has incorporated a relational data base into a mainframe computer, the NEC ACOS System 430, and as of March 1989 it can retrieve and graphically present borehole, deep-well, and groundwater data.The authors wish to introduce in this article the organizational structure of the Geotechnical Data Information System of TMG, a summary of the data base system, standards of input data, and applicable examples of the data base.     

Japanese national program on earthquake prediction

Earthquake prediction studies in Japan have made progress since a national program was officially launched in 1965. A sum of 18 million dollars has been allocated for the program in addition to expenses for salaries, construction of observatories and other supporting routines. As a result, 17 crustal deformation observatories, 19 microearthquake observatories and 1 magnetic observatory, all equipped with modern instruments have been completed. It has also become possible to repeat the first-order levelling surveys along levelling routes of 20,000 km in length with an interval of five years.The program has been tested during the 1965—1966 Matsushiro activity of swarm earthquakes. Judging from the fact that long-term predictions could be issued to the public from time to time during the active period, the program would seem to be directed in the right direction. An anomalous land deformation has been found in an area south of Tokyo in 1969. An operation to investigate the anomaly has been carried out intensively over the area concerned with special emphasis on detecting the possibilities of a large earthquake occurring there.Intensification of the program orientated towards actual prediction is now under consideration. A more extensive program including a nation-wide network of geodimeter surveys, real-time monitoring of microearthquakes, real-time observations by oceanbottom seismographs and other disciplines is going to be planned.     

Vulnerability Analysis in Earthquake Loss Estimate

The abodes in Costa Rica have almost the samevulnerability as the old civil houses in China, whichrepresent the vulnerability in worst cases. On theother hand, the high quality buildings in Middle Easthave the same vulnerability as the reinforced concretebuildings in China due to employing thestate-of-art-design and construction techniques, whichrepresent the vulnerability of the best cases. Themacroeconomic vulnerability is defined as the ratio ofphysical economic loss caused by earthquake to theGross Domestic Product (GDP) within a given area.Since the total macroscopic loss is the sum of lossesof different types of buildings and facilities, themacroeconomic vulnerability must be greater than thatof best cases while less than that of worst cases. Inthe present paper, the implications of macroeconomicvulnerability to earthquake loss estimate arediscussed.     

Constructing a social vulnerability index to earthquake hazards using a hybrid factor analysis and analytic network process (F’ANP) model

Iran is a seismic prone country and has been host to a long series of devastating earthquakes which have resulted in heavy casualties and damages. In order to assess social vulnerability (SV) to earthquake hazards, this paper presents the development of a hybrid factor analysis and analytic network process model for aggregating vulnerability indicators into a composite index of SV to earthquake hazards. The proposed model is then applied in Iran as a case study. The proposed model uses factor analysis (FA) to extract the underlying dimensions of SV. The identified dimensions of SV and their primary variables are then entered into a network model in Analytic Network Process (ANP). The ANP is used to calculate the relative importance of different SV variables, taking into consideration the results obtained from FA and the possible interdependence between variables of the individual dimensions of SV. These weights are then used to compute the factor scores for the individual dimensions of SV and also the composite social vulnerability index (SOVI). The application of the proposed model to a real world case study and its validation show that it is a robust approach for constructing a composite SOVI. Its application to counties in Iran indicates that there exist severe regional differences in terms of SV to earthquake hazards. The pronounced regional variations in SV warrant special attention by both local authorities and the national government to reconsider current natural disaster management strategies.     

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.     

Vulnerability assessment based on household views from the Dammar Char in Southeastern Bangladesh

Assessing vulnerability is vital for developing new strategies and improving the existing ones to fulfill contemporary demands toward achieving a disaster-resilient society. Dammar Char is situated in the southeastern (SE) coastal region of Bangladesh that has experienced frequent coastal hazards and disasters throughout the year. The present study has constructed a vulnerability index utilizing the quantitative and qualitative data based on household surveys to evaluate the vulnerability of the people and community of Dammar Char. Data were collected from 180 respondents during November–December 2018. The results demonstrate that, on average, the people living in the studied area have a high vulnerability (value of the vulnerability index 0.7015) to coastal hazards and disasters. The vulnerability level differs from individual to individual based on their gender, educational status, financial capacity, structural strength of houses, perception of the respective hazards and disasters, etc. Females have experienced more vulnerability than their adult male counterparts. The natural vulnerability was higher than socioeconomic and physical vulnerability due to the increase in unpredictable extreme climate-induced coastal events. To combat the adverse impacts of coastal hazards and disasters, the local Dammar Char inhabitants have adopted several adaptation measures. The adapted measures are homestead gardening, working in seasonal day labor, fish drying, rearing sheep, and ducks, constructing plinths for elevating the floor of the house, extensive banana cultivation, and storage of dry foods to reduce their vulnerability.

     

Tsunami vulnerability evaluation in the Mentawai islands based on the field survey of the 2010 tsunami

On October 25, 2010, a large earthquake occurred off the coast of the Mentawai islands in Indonesia, generating a tsunami that caused damage to the coastal area of North Pagai, South Pagai, and Sipora islands. Field surveys were conducted soon after the event by several international survey teams, including the authors’. These surveys clarified the tsunami height distribution, the damage that took place, and residents’ awareness of tsunamis in the affected islands. Heights of over 5 m were recorded on the coastal area of the Indian Ocean side of North and South Pagai islands and the south part of Sipora island. In some villages, it was difficult to evacuate immediately after the earthquake because of the lack of routes to higher ground or the presence of rivers. Residents in some villages had taken part in tsunami drills or education; however, not all villages shared awareness of tsunami threats. In the present paper, based on the results of these field surveys, the vulnerability of these islands with regards to future tsunami threats was analyzed. Three important aspects of this tsunami disaster, namely the geographic disadvantage of the islands, the resilience of buildings and other infrastructure, and people’s awareness of tsunamis, are discussed in detail, and corresponding tsunami mitigation strategies are explained.     

Integrated model for earthquake risk assessment using neural network and analytic hierarchy process:Aceh province,Indonesia

Catastrophic natural hazards,such as earthquake,pose serious threats to properties and human lives in urban areas.Therefore,earthquake risk assessment(ERA)is indispensable in disaster management.ERA is an integration of the extent of probability and vulnerability of assets.This study develops an integrated model by using the artificial neural network–analytic hierarchy process(ANN–AHP)model for constructing the ERA map.The aim of the study is to quantify urban population risk that may be caused by impending earthquakes.The model is applied to the city of Banda Aceh in Indonesia,a seismically active zone of Aceh province frequently affected by devastating earthquakes.ANN is used for probability mapping,whereas AHP is used to assess urban vulnerability after the hazard map is created with the aid of earthquake intensity variation thematic layering.The risk map is subsequently created by combining the probability,hazard,and vulnerability maps.Then,the risk levels of various zones are obtained.The validation process reveals that the proposed model can map the earthquake probability based on historical events with an accuracy of 84%.Furthermore,results show that the central and southeastern regions of the city have moderate to very high risk classifications,whereas the other parts of the city fall under low to very low earthquake risk classifications.The findings of this research are useful for government agencies and decision makers,particularly in estimating risk dimensions in urban areas and for the future studies to project the preparedness strategies for Banda Aceh.     

A multi-criteria evaluation model of earthquake vulnerability in Victoria,British Columbia

Researchers have recently examined the geographic variability of the vulnerability of populations to earthquakes. These studies focus mainly on the complex modelling of geophysical processes or identification of socio-economically disadvantaged populations. However, no studies to date have integrated different components of vulnerability with metrics of travel distance to hospitals and trauma centres (systemic vulnerability). We argue that this previously unaccounted component is an important conceptual and practical aspect of earthquake vulnerability. Accordingly, this paper presents a multi-criteria model for combining physical, social, and systemic components, moving towards a more comprehensive assessment of vulnerability. An analytic hierarchy process is used to produce a place-specific index of social vulnerability, which we combine with soil liquefaction and amplification index and a road network model for access to hospitals and trauma services. Using a geographic information system, we implemented this model for the Greater Victoria region (483 km², 2011 population: 345,000) in British Columbia, Canada. Clustering of total vulnerability was found in outlying areas, highlighting the importance of access to trauma centres. We conclude by identifying challenges in measuring earthquake vulnerability and advocate integration of systemic vulnerability components in natural hazards research.     

泥石流作用下建筑物易损性评价方法分析与评价

建筑物易损度评价作为泥石流易损度评价的重要组成部分,其研究是实现城镇及居民点泥石流风险定量化和风险管理的必要环节。综述近30年来,泥石流作用下建筑物易损度研究的发展过程,并指出以统计分析方法建立的建筑物易损度曲线普适性差且力学机理不明等问题,提出数值计算和模型实验的手段获取建筑物结构易损度的机理模型。由于建筑物易损度研究问题本身的复杂性,统计分析方法仍将作为建筑物易损度研究的重要手段,力学机理明晰的研究方法则将成为今后研究的难点和热点。此外,地震、滚石、雪崩等类似灾种的易损度研究方法和成果可被借鉴到泥石流领域。针对灾害中因结构破坏引发人员伤亡的情况,建议采用时间概率和基于条件概率的事件树方法计算建筑物内人员易损度。最终形成综合结构和人员易损度研究成果的建筑物易损度评价方法。