Miguel G. Mora

Hybrid loss exceedance curve (HLEC) for disaster risk assessment

Taken into account that the natural hazard risk is a contingent liability and, therefore, a sovereign risk for national governments, it is important to assess properly the potential losses to design a suitable risk reduction, retention and transfer strategy. In this article, a disaster risk assessment methodology is proposed based on two approaches: on the one hand, the empiric estimation of losses, using information available from local disaster databases, allowing estimating losses due to small-scale events and, on the other hand, probabilistic evaluations to estimate losses for greater or even catastrophic events, for which information usually is not available due to the lack of historical data. A “hybrid” loss exceedance curve is thus determined, which combines the results of these two approaches and represents the disaster risk in a proper and complete way. This curve merges two components: the corresponding to small and moderate losses, calculated using an inductive and retrospective analysis, and the corresponding to extreme losses, calculated using a deductive and prospective analysis. Applications of this risk assessment technique are given in this article for eleven countries.

Fully probabilistic seismic risk assessment considering local site effects for the portfolio of buildings in Medellín, Colombia

A fully probabilistic seismic risk analysis using a comprehensive approach is conducted for Medellin, the second largest city of Colombia, using a building by building database constructed and complemented from aerial images, considering characteristics such as building use categories, socio-economic levels and replacement values. The seismic hazard used for the analysis corresponds to the most updated study available in the country with the same model that was included in the national building code maps definition. Spectral transfer functions are determined for each of the seismic microzonation zones in order to take into account the dynamic soil response and amplification effects in the risk analysis. Several building types are defined for the city and individual vulnerability functions are assigned to each of them. Risk results are presented in the state of the art metrics such as the loss exceedance curve, probable maximum losses for different return periods, average annual losses and risk maps. The obtained results can be classified by use and socio-economic sectors as well as by structural systems that may help the stakeholders to identify where the risk concentrates.

Methodology and applications for the benefit cost analysis of the seismic risk reduction in building portfolios at broadscale

This article presents a methodology for an estimate of the benefit cost ratio of the seismic risk reduction in buildings portfolio at broadscale, for a world region, allowing comparing the results obtained for the countries belonging to that region. This methodology encompasses (1) the generation of a set of random seismic events and the evaluation of the spectral accelerations at the buildings location; (2) the estimation of the buildings built area, the economic value, as well as the classification in structural typologies; (3) the development of vulnerability curves for each typology; (4) the estimation of the annual average loss of the buildings portfolio in the current conditions as well as in the case of a hypothetical structural intervention. The benefit cost ratio is estimated as the difference between the estimates of the present value of these two annual average losses, divided by the retrofitting costs. This methodology has been applied to the portfolio of public schools of 14 countries of Latin America and the Caribbean, for evaluating the feasibility of the seismic risk reduction at a national scale.

Design and implementation of a voluntary collective earthquake insurance policy to cover low-income homeowners in a developing country

Understanding and evaluating disaster risk due to natural hazard events such as earthquakes creates powerful incentives for countries to develop planning options and tools to reduce potential damages. The use of models for earthquake risk evaluation allows obtaining outputs such as the loss exceedance curve, the expected annual loss and the probable maximum loss, which are probabilistic metrics useful for risk analyses, for designing strategies for risk reduction and mitigation, for emergency response strategies and for risk financing. This article presents, based on probabilistic risk models, the design and implementation of a risk transfer instrument to cover the private buildings of the city of Manizales, Colombia. This voluntary collective instrument provides financial protection to both, the estate tax payers and the low-income homeowners through a cross-subsidy strategy; besides, it promotes not only the insurance culture but also the solidarity of the community. The city administration and the insurance industry are promoting this program using the mechanism of the property tax payment. This collective insurance helps the government to access key resources for low-income householders recovery and improve disaster risk management at local level.

Prioritizing interventions to reduce seismic vulnerability in school facilities in Colombia

The Colombian seismic code NSR-98 establishes the requirement for the seismic vulnerability analysis and, if necessary, the strengthening of public facilities (schools). Due to the investments required by risk-reduction programs, it is necessary to establish criteria for assigning priorities for the interventions. This article proposes a methodology for obtaining a benefit-cost ratio (BCR) at the subnational level, by assessing the expected annual average loss of the built area of public schools and the retrofitting cost. The BCR is estimated as the difference between the estimates of the net present value for status quo and retrofitted states, both divided by the retrofitting costs. According to the BCR, 47.3% of the total school-built area of Colombia should be retrofitted where the retrofitting costs correspond to 25% of the total investment. Proposed BCR is useful for prioritizing regions as a function of the feasibility of reducing the seismic vulnerability of the schools.