An integrated assessment of seismic hazard exposure and its societal impact in Seven Sister States of North Eastern Region of India for sustainable disaster mitigation planning

The Seven Sister States of the North Eastern Region of India, located on the complex seismotectonic belt, is characterized by high seismicity. A comprehensive seismic hazard exposure assessment is carried out by quantifying hazard using a probabilistic approach, vulnerability by factor analysis, and exposure mapping by integrating seismic hazard and vulnerability. Peak ground acceleration (PGA) values at bedrock are calculated with the help of ground motion prediction equations (GMPE) for 10% probability of exceedance in 50 years (475 years) and 100 years (950 years), and 2% probability of exceedance in 50 years (2475 years). The resulting spatial distribution of the PGA values considering return periods of 475, 950, and 2475 years are presented through seismic hazard maps. The social vulnerability analysis indicates that 21 districts covering 91.43% area of the state of Assam and the entire state of Tripura are under high vulnerability. With the help of spatial cluster analysis, it is found that 17.14% of the study area are having an average social vulnerability index (SVI) score of 0.329 and therefore can be considered as hotspots. Through seismic hazard analysis, it is observed that more than 50% of the area of North East India is under moderate to very high exposure class. The seismic hazard maps developed can help in disaster mitigation planning and execution leading to sustainable development goals and targets.

Prioritising Earthquake Retrofitting in the High in Wellington CBD

Strengthening buildings can minimize the earthquakes’ life safety risk. Wellington has around 800 office buildings that might have structural and non-structural seismic vulnerabilities. Given a limited budget and other constrains, prioritization of retrofitting buildings has become a fundamental topic for decision makers. Different methods have been developed to define prioritisation strategies of retrofitting building on a wide territorial scale. In this paper, we applied the multi-criteria decision making (MCDM) analysis to define different propriety ranking able to satisfy different purpose. Moreover, Fuzzy TOPSIS and VIKOR are two MCDM methods are applied to compare the results. In order to help decision makers in choosing the optimal mitigation strategy with multidimensional perspective, different political and social scenarios are also defined. Based on available seismic risk information (vulnerability, seismic hazard, exposure) the prioritization can be identified. Our aims are: (1) to describe the priority scenarios based on the seismic risk. (2) to rank retrofitting buildings based on different purpose. (3) to relate these findings to possible lessons for policy makers when designing retrofit building strategies.

Prioritising Earthquake Retrofitting in the High in Wellington CBD

Strengthening buildings can minimize the earthquakes’ life safety risk. Wellington has around 800 office buildings that might have structural and non-structural seismic vulnerabilities. Given a limited budget and other constrains, prioritization of retrofitting buildings has become a fundamental topic for decision makers. Different methods have been developed to define prioritisation strategies of retrofitting building on a wide territorial scale. In this paper, we applied the multi-criteria decision making (MCDM) analysis to define different propriety ranking able to satisfy different purpose. Moreover, Fuzzy TOPSIS and VIKOR are two MCDM methods are applied to compare the results. In order to help decision makers in choosing the optimal mitigation strategy with multidimensional perspective, different political and social scenarios are also defined. Based on available seismic risk information (vulnerability, seismic hazard, exposure) the prioritization can be identified. Our aims are: (1) to describe the priority scenarios based on the seismic risk. (2) to rank retrofitting buildings based on different purpose. (3) to relate these findings to possible lessons for policy makers when designing retrofit building strategies.

An interdisciplinary perspective on social and physical determinants of seismic risk

While disaster studies researchers usually view risk as a function of hazard, exposure, and vulnerability, few studies have systematically examined the relationships among the various physical and socioeconomic determinants underlying disasters, and fewer have done so through seismic risk analysis. In the context of the 1999 Chi-Chi earthquake in Taiwan, this study constructs three statistical models to test different determinants that affect disaster fatality at the village level, including seismic hazard, exposure of population and fragile buildings, and demographic and socioeconomic vulnerability. The Poisson regression model is used to estimate the impact of these factors on fatalities. Research results indicate that although all of the determinants have an impact on seismic fatality, some indicators of vulnerability, such as gender ratio, percentages of young and aged population, income and its standard deviation, are the important determinants deteriorating seismic risk. These findings have strong social implications for policy interventions to mitigate such disasters.

Comparisons among Earthquake Codes

This review paper compares ANSI, NEHRP, SEAOC, and UBC. A few essential differences among these documents are as follows: (a) The NEHRP document gives force levels corresponding to a strength-based or limit states design, while the other three documents give force levels that correspond to working or service stress design; (b) the importance factor is used as a multiplier of base shear level in all documents except NEHRP, which treats building importance by a seismic hazard exposure group; (c) NEHRP and UBC-1988 contain detailing requirements for all common construction materials and all seismic zones, while UBC-1985 contains detailing requirements for zones of high seismicity but only limited requirements for zones of moderate seismicity; (d) P-delta analysis is specified by NEHRP for all buildings that must be analyzed, by SEAOC for buildings that exceed drift limits, by UBC-1988 for all buildings except those in Zones 3 and 4 meeting drift limits, and is not specified by ANSI.