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Report on the workshop for the participatory evaluation of earthquake risk and resilience in Addis Ababa, Ethiopia
Type:
Report
Year:
2017
An essential step to understand and enhance the resilience of cities to earthquakes is to measure the concept. Measurement is vital not only to evaluate and benchmark the baseline conditions of what makes communities resilient but also to help communities to understand the factors that lead to losses and the differential ability of populations across and within communities to recover when damaging events occur. To address this, GEM and the United States Agency for International Development (USAID) collaborated to facilitate the Resilience Performance Scorecard (RPS) workshop in Addis Ababa, Ethiopia. The RPS is a multi-level and multi-scale self-evaluation tool that empowers stakeholders to assess earthquake resilience parameters based primarily on qualitative information. Here, an interactive voting system is used in a workshop setting to identify priorities where activities may be pertinent for earthquake risk reduction or where existing initiatives may be improved to increase earthquake resilience in different sectors of society. Six dimensions of earthquake resilience are encompassed to address key areas that mainstream risk reduction namely; planning and decision-making processes, 10 social capacity, awareness and advocacy, legal and institutional arrangements, planning and regulation, critical infrastructure and services, and emergency preparedness and response.
Combining USGS ShakeMaps and the OpenQuake-engine for damage and loss assessment
Type:
Peer-reviewed
Year:
2019
The evaluation of the potential impact of strong seismic events shortly after their occurrence is a critical step to organise emergency response and consequently minimise the adverse effects of earthquakes. The estimation of the impact from earthquakes considering the observed ground shaking from past events can be useful for the calibration of existing exposure and/or fragility and vulnerability models. This study describes a methodology to combine the publicly available information from the USGS ShakeMap system and the open‐source software OpenQuake engine for the assessment of damage and losses. This approach is employed to estimate the number of structural collapses considering the 2012 Magnitude 5.9 Emilia‐Romagna (Italy) earthquake and the aggregated economic loss because of the 2010 Magnitude 7.1 Darfield (New Zealand) event. Several techniques to calculate the ground shaking in the affected region considering the spatial and interperiod correlations in the intra‐event ground motion residuals are investigated and their influence in the resulting damage or loss estimates are evaluated.
Evaluation of Seismic Risk on UNESCO Cultural Heritage sites in Europe
Type:
Peer-reviewed
Year:
2018
Earthquakes have been responsible for the destruction of hundreds of monuments throughout human history. Due to their size, conservation state, and lack of seismic provisions, monuments are particularly vulnerable to the effects of geological hazards. The first step toward the mitigation of the earthquake threat consists of understanding the existing seismic risk and evaluating possible strategies to reduce it. This study presents a simplified assessment to evaluate the probability of damage due to ground shaking on UNESCO World Heritage cultural sites throughout Europe. The seismic hazard model (SHARE) has been employed to derive hazard curves, which were combined with a fragility model to calculate the annual probability of damage or collapse. These calculations were performed assuming different soil conditions, and the resulting risk metrics can be used for risk awareness, to inform the prioritization of the sites in need of structural interventions, and to support additional risk analysis.
Development of a Probabilistic Earthquake Loss Model for Iran
Type:
Peer-reviewed
Year:
2017
Iran is located in one of the most seismically active regions of the world. This high seismicity combined with densely populated regions has led to several destructive earthquakes in the past, such as the M7.4 Tabas (1978), M7.4 Manjil–Rudbar (1990), or the M6.6 Bam (2003). Seismic hazard and risk assessment can provide critical information to decision makers for the development of efficient risk reduction measures. In this study, exposure models for the residential, commercial and industrial building stock were developed using recent housing census information, socio-economic data and the judgement of local experts. For each building class in the exposure model, a set of fragility and vulnerability models was derived using nonlinear time history analysis and ground motion records from the region. The exposure and vulnerability models were combined with the recently released Earthquake Model for the Middle East (EMME) to estimate probabilistic earthquake losses using the OpenQuake-engine. These results identify the regions within the country with the highest risk, the most vulnerable building classes, and the expected economic losses for a number of return periods.
The Global Earthquake Model Physical Vulnerability Database
Type:
Peer-reviewed
Year:
2016
There are almost 50 years of research on fragility and vulnerability assessment, both key elements in seismic risk or loss estimation. This paper presents the online database of physical vulnerability models that has been created as part of the Global Earthquake Model (GEM) initiative. The database comprises fragility and vulnerability curves, damage-to-loss models, and capacity curves for various types of structures. The attributes that have been selected to characterize each function, the constraints of setting up a usable database, the challenges in collecting these models, and the current trends in the development of vulnerability models are discussed in this study. The current collection of models leverages upon the outputs of several initiatives, such as GEM's Global Vulnerability Consortium and the European Syner-G project. This database is publicly available through the web-based GEM OpenQuake-platform http://doi.org/10.13117/GEM.DATASET.VULN.WEB-V1.0.
Critical Issues in Earthquake Scenario Loss Modeling
Type:
Peer-reviewed
Year:
2016
The assessment of human or economic losses due to single events (scenario) may effectively support decision makers in the development of important risk mitigation actions. The study presented herein sheds light on several problems and limitations in the current practice of scenario loss modeling, such as: the number of simulations required to achieve convergence; epistemic and aleatory uncertainty in the ground motion prediction and vulnerability models; and consideration of the earthquake rupture geometry. These issues are investigated using the Metropolitan Area of Lisbon (Portugal), and it has been observed that distinct assumptions in the loss modeling can lead to considerably different results. The findings of this study are also pertinent for probabilistic seismic risk analyses in which a large number of stochastically generated events are employed to assess probabilistic losses.
Critical Issues on Probabilistic Earthquake Loss Assessment
Type:
Peer-reviewed
Year:
2017
Probabilistic loss modeling can be used to develop risk reduction measures, such as the identification of regions more prone to human and economic losses, or to develop financial mechanisms to transfer the earthquake risk from local governments to the private sector. This study addresses several critical issues in probabilistic loss modeling, and provides recommendations depending on the intended final use of the risk results. Modeling issues related to convergence in probabilistic event-based analysis; consideration of epistemic uncertainties within a logic tree; generation of different types of loss exceedance curves; and derivation of risk maps are thoroughly investigated. The Metropolitan Area of Lisbon is used to explore these issues, and it is demonstrated that different assumptions in the loss modeling process can lead to considerably different risk results. Furthermore, the findings and recommendations of this study are also relevant for institutions that promote the assessment of earthquake hazard and risk, such as the Global Earthquake Model Foundation.
Assessing Integrated Earthquake Risk in OpenQuake with an Application to Mainland Portugal
Type:
Peer-reviewed
Year:
2015
At the forefront of the risk assessment sciences is the development of standards, data, and tools for the assessment of earthquake risk. Countries such as Portugal have been targets of extensive earthquake risk assessments to communicate damage potential and to improve methodologies. Few studies, however, have gone beyond the estimation of direct physical impacts by integrating estimates of physical risk (i.e., human or economic losses) with quantified metrics of socioeconomic characteristics of populations. The purpose of this paper is to describe an end-to-end assessment of earthquake risk for mainland Portugal that accounts for physical and social attributes using the Global Earthquake Model's (GEM) suite of risk assessment tools. The results indicate that the potential adverse effects from earthquakes in Portugal are related to interacting conditions, some conditional on geography, some due to the characteristics of the building stock, and some having to do with the social characteristics of populations.
Exploring the seismic risk of the unreinforced masonry building stock in Antioquia, Colombia
Type:
Peer-reviewed
Year:
2017
Abstract This paper presents the development of an exposure model for the residential building stock in Antioquia (the second most populated Department of Colombia), the development of fragility functions for unreinforced masonry buildings, and estimation of building damage for two possible seismic events. Both the exposure and fragility models are publically available and can be used to calculate damage and losses due to single events, or probabilistic seismic hazard. The exposure model includes information regarding the total built-up area, number of buildings and inhabitants, building class, and replacement cost. The methodology used for the creation of the exposure model was based on available cadastral information, survey data, and expert judgment. Fragility functions were derived using nonlinear time history analyses on single-degree-of-freedom oscillators, for unreinforced masonry structures which represent more than 60% of the building stock in the region. Both seismic scenarios indicate that an event corresponding to a return period of 500 years located within the region of interest would cause slight or moderate damage to nearly 95 thousand structures, and about 32 thousand would have severe damage or collapse. This study was developed as part of the South America Risk Assessment project, supported by the Global Earthquake Model and SwissRe Foundation.
Development of a Fragility Model for the Residential Building Stock in South America
Type:
Peer-reviewed
Year:
2016
South America—in particular, the Andean countries—are exposed to high levels of seismic hazard, which, when combined with the elevated concentration of population and properties, has led to an alarming potential for human and economic losses. Although several fragility models have been developed in recent decades for South America, and occasionally used in probabilistic risk analysis, these models have been developed using distinct methodologies and assumptions, which renders any direct comparison of the results across countries questionable, and thus application at a regional level unreliable. This publication aims at obtaining a uniform fragility model for the most representative building classes in the Andean region, for large-scale risk analysis. To this end, sets of single-degree-of-freedom oscillators were created and subjected to a series of ground motion records using nonlinear time history analyses, and the resulting damage distributions were used to derive sets of fragility functions.
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