A comparison of seismic risk maps for Italy

National seismic risk maps are an important risk mitigation tool as they can be used for the prioritization of regions within a country where retrofitting of the building stock or other risk mitigation measures should take place. The production of a seismic risk map involves the convolution of seismic hazard data, vulnerability predictions for the building stock and exposure data. The seismic risk maps produced in Italy over the past 10 years are compared in this paper with recent proposals for seismic risk maps based on state-of-the-art seismic hazard data and mechanics-based vulnerability assessment procedures. The aim of the paper is to open the discussion for the way in which future seismic risk maps could be produced, making use of the most up-to-date information in the fields of seismic hazard evaluation and vulnerability assessment.     

Analysis of damage data of low-rise buildings subjected to a shallow Mw6.3 earthquake

In May 2008 a shallow M_w6.3 earthquake struck South Iceland with an epicentre close to two small towns. Nearly 5000 low-rise residential buildings were affected. The recorded maximum PGA was 0.88 g. A great deal of damage occurred, but there was no loss of life. In Iceland all buildings are registered in a detailed official database and insurance against natural disasters is obligatory. As the repair costs for every affected building had to be assessed for insurance purposes this provided an unusual opportunity to review structural performance across the whole population of buildings in the affected area. The estimated repair cost was classified in a number of subcategories covering structural and non-structural damage for five different residential building typologies. Study of these buildings showed that non-structural damage dominated the overall damage. The main monetary damage was cosmetic damage of partition walls and flooring. The structural systems performed quite well and no buildings collapsed.     

Evaluation of CPT-based Liquefaction Procedures at Regional Scale

The liquefaction database describing the response of the Christchurch area in the 2010–2011 Canterbury Earthquake Sequence (CES) provides a unique basis for evaluating the regional application of various liquefaction analysis procedures, from liquefaction triggering analyses through to liquefaction vulnerability parameters. This database was used to compare the Robertson and Wride [17], Moss et al. [15] and Idriss and Boulanger [7] liquefaction triggering procedures as well as evaluate the impact of the 2014 versus 2008 Cone Penetration Test (CPT)-based liquefaction triggering procedure by Idriss and Boulanger on four liquefaction vulnerability parameters (S_V1D, LPI, LPI_ISH and LSN), the correlation of those parameters with observed liquefaction-induced damage patterns in the CES, and the mapping of expected damage levels for 25, 100 and 500 year return period ground motions in Christchurch. The effects on S_V1D, LPI, LPI_ISH and LSN were small relative to other sources of variability for the majority of the affected areas, particularly where liquefaction was clearly severe or clearly not. Nonetheless, considering the separation of the land damage populations as well as consistency between the events, the the IB-2008 liquefaction triggering procedures appears to give a slightly better fit to the mapped liquefaction-induced land damage for the regional prediction of liquefaction vulnerability for the Christchurch soils. The Boulanger and Idriss [1] triggering procedure produces improved agreement between the liquefaction vulnerability parameters and observations of damage for: areas south of the Central Business District (CBD) where there tends to be higher soil Fines Content (FC), and localized areas that experienced liquefaction during the smaller Magnitude (M) earthquake events. Implementation of the 2014 liquefaction triggering procedure for mapping of expected liquefaction-induced damage at 25, 100 and 500 year return period ground motions is shown to require use of representative Peak Ground Acceleration (PGA)-M values consistent with the de-aggregation of the seismic hazard. Use of equivalent magnitude-scaled PGA-M7.5 pairs, where the equivalency relates to previously published MSF relationships, with the 2014 liquefaction triggering procedure is shown to be unconservative for certain situations.     

辽宁矿业城市经济系统应对能力分析及其脆弱性评价

矿业城市经济系统脆弱性是关于敏感性和应对能力的一组函数关系式,而其应对能力的影响因素很多,为了实现指标降维和客观赋值,借助主成分分析法和熵值法来简化运算;并构建脆弱性评估模型,以辽宁主要矿业城市为样本进行脆弱性评价。结果表明:(1)矿业城市经济系统脆弱性随其生命周期的推进而逐渐增大,侧面说明经济发展对资源具有高度的"路径依赖"及其产业结构的单一;(2)经济系统面对资源枯竭、国有企业改组改革扰动的敏感性对决定其脆弱性程度作用更为显著;(3)所选样本城市中,阜新市的脆弱度最高,鞍山最低,且在地域分布上呈现出辽东辽西的趋势。最后依据脆弱性特征将案例城市划分为3种类型。     

Perception of flood risk in Danube Delta,Romania

For exposed and vulnerable communities, the perception of natural risk is an essential link in the analysis of man–environment coping relationship and also an important parameter in the quantification of complex vulnerability as a central predictive variable in the risk equation. The topic of flood risk in related perception is of considerable interest, as some recently published papers have proven (Messner and Meyer 2005, 2006; Raaijmakers et al. 2008). The aim of the current study is to reveal the conscious and unconscious attitudes towards the flood risk for the inhabitants of the Danube Delta/Romania. These attitudes, defined by different degrees of psychological vulnerability, represent the background for a series of psycho-behavioural patterns that generate certain adjustment mechanisms and strategies. Application of a specially designed questionnaire and the statistical analysis of the results revealed two psychological factors as essential in establishing the psychosocial vulnerability degree of the interviewed subjects: (i) an internal control factor and (ii) an external control factor. The persons characterized by inner control have a significantly reduced general anxiety level in comparison to individuals with the control factor placed externally. As confidence diminishes, it increases the tendency of the individual to rely on the external factors for support and security. The lack of resources (indicating lower resilience) and mistrust in the support given emphasizes non-adaptive behaviours.

延安宝塔山景区滑坡地质灾害风险评估

滑坡灾害易损性可分为两大类型:人口易损性和经济易损性。本文依据现场风险填图对宝塔山景区影响居民生命和财产安全的地质灾害进行了风险源的识别,认为宝塔山景区的风险源主要为潜在的滑坡及崩塌灾害,最大风险处人员伤亡总概率为2.6210-2a-1;同时,依据工程地质经验法对风险管理易损性各要素进行了定量评价,认为对宝塔山景区居民来说,100a以内居民平均每年有最大2.62%伤亡的概率存在。根据国际较通用的风险容许标准,认为目前部分宝塔山居民遭受的风险处于不可接受区,建议加强监测。     

区域雷灾易损性及其区划的实证分析

分析了区域自然环境、经济状况和雷电灾害情况,根据江西省雷电灾害资料和年平均雷暴日统计资料,选取雷击密度、雷电灾害频数、经济易损指标、生命易损指标作为雷灾易损性评价指标。对江西省各设区市的雷灾易损性进行了综合评估,初步形成了江西省雷灾易损度区划。提出了区域雷灾易损性分析和区划的模式,为区域防御和减低雷电损失的规划提供了科学依据。     

Gender,ethnicity and vulnerability to climate change: The case of matrilineal and patrilineal societies in Bamenda Highlands Region,Cameroon

Intersectionality is gaining credence in explaining the complexities in rural women’s vulnerability to the impacts of climate change. This study is framed on the assumption that rural women are likely to be affected differently by climate change due to cultural differences. The life history approach was utilised to conduct empirical research in the Bamenda Highlands Region, Cameroon on ethnicity and differential effects of climate change among female farmers in the communities of Kom and Oku representing a matrilineal and patrilineal communities respectively. The research found that single and married women in both matrilineal and patrilineal societies experienced similar patterns of vulnerability relating to socio-economic and cultural discrimination stemming from patriarchal dominance. However, the study also highlighted that contrary to other communities women are not more economically empowered under matrilineal systems than their counterparts in patrilineal societies. In contrast, widows in patrilineal societies were found to have more autonomy in the control of land and other resources than those in matrilineal societies. The study contributes to growing interest in the cultural dimensions of vulnerability to climate change and recommends the inclusion of cultural perspectives in the design and implementation of adaption policies, programs and actions.     

An assessment of the risk associated with urban development in the Thiaroye area (Senegal)

Water quality data from 56 wells, aquifer characteristics, soil types and land use in the city suburb of Dakar were compared to assess the effects of land use on the Thiaroye groundwater quality. The study area encompassed an unsewered densely populated zone, agricultural land, low density villages, and undeveloped land located in the sand dunes. A method similar to GIS technologies was applied to evaluate the degree of vulnerability of the different parts of the aquifer in relation to urban development, land use and aquifer characteristics. The aquifer parameters (hydraulic conductivity, groundwater level depth, recharge, soil type) were re-evaluated qualitatively into three class rankings (high, moderate and low), depending on the likelihood for contaminants reaching the water table, then combined using the two matrix Boolean logic based approaches to identify the nine classes of vulnerability assessed in the aquifer domain. An attempt was made to explain the distribution of nitrate concentration with the assessed vulnerability. In the area assessed, in the densely populated zone running from Pikine, to Thiaroye and Yeumbeul, very high nitrate concentrations correspond with the highest vulnerability index (H1). Nitrate contamination in this area is a consequence of point-source seepage from individual septic systems improperly built in this area. In the eastern part of the aquifer, high nitrate concentrations at Deni B. Ndao, Mbawane and Golam localities coincide with a moderate vulnerability assessment. The major source of nitrate in these areas is induced by agricultural activities.     

Vulnerability evaluation of a coastal plain sand aquifer with a case example from Calabar,southeastern Nigeria

A point count index method using a well drillers log and field measurements has been developed following the DRASTIC and SINTACS procedures to map and evaluate the vulnerability of a coastal plain aquifer to surface and near surface contamination. The input parameters with the acronym CALOD include clay layer thickness (C), aquifer media character (A), lateritic layer thickness (L), overlying layer character (O) and the depth to groundwater level (D). The CALOD vulnerability potential index (CALOD index) is computed as the sum of the products of weights and ratings assigned to each of the input parameters. The CALOD index, varying between 15 and 75, is divided into four classes: high (>60), high-medium, (40–60), low-medium (20–40) and low (<20). The CALOD index is then used to produce a vulnerability potential map for the area. From the map, areas of high, high-medium and medium-low are consistent with the upper gravelly aquiferous zone while areas of medium-low and low are restricted to the deeper lower sandy aquiferous layer. The most important parameters affecting groundwater vulnerability to pollution in coastal areas include saturated thickness of the aquifer, depth to groundwater level, lateritic layer thickness and the aquifer media character. The concentration of some chemical pollution indicators (electrical conductivity, K, NO₃, Cl and metal load) are relatively higher for the highly vulnerable shallower upper gravelly unit in comparison to the less vulnerable deeper sandy unit. This method is very suitable for coastal plain sand aquifers especially, where data is scare.