Integration of Probabilistic and Multi-Hazard Risk Assessment Within Urban Development Planning and Emergency Preparedness and Response: Application to Manizales,Colombia

The details of a multi-hazard and probabilistic risk assessment, developed for urban planning and emergency response activities in Manizales, Colombia, are presented in this article. This risk assessment effort was developed under the framework of an integral disaster risk management project whose goal was to connect risk reduction activities by using open access and state-of-theart risk models. A probabilistic approach was used for the analysis of seismic, landslide, and volcanic hazards to obtain stochastic event sets suitable for probabilistic loss estimation and to generate risk results in different metrics after aggregating in a rigorous way the losses associated to the different hazards. Detailed and high resolution exposure databases were used for the building stock and infrastructure of the city together with a set of vulnerability functions for each of the perils considered. The urban and territorial ordering plan of the city was updated for socioeconomic development and land use using the hazard and risk inputs and determinants, which cover not only the current urban area but also those adjacent areas where the expansion of Manizales is expected to occur. The emergency response capabilities of the city were improved by taking into account risk scenarios and after updating anautomatic and real-time post-earthquake damage assessment.

Numerical analysis of rapid drawdown: Applications in real cases

In this study, rapid drawdown scenarios were analyzed by means of numerical examples as well as modeling of real cases with in situ measurements. The aim of the study was to evaluate different approaches available for calculating pore water pressure distributions during and after a drawdown. To do that, a single slope subjected to a drawdown was first analyzed under different calculation alternatives, and numerical results were discussed. Simple methods, such as undrained analysis and pure flow analysis, implicitly assuming a rigid soil skeleton, lead to significant errors in pore water pressure distributions when compared with coupled flow-deformation analysis. A similar analysis was performed for the upstream slope of the Glen Shira Dam, Scotland, and numerical results were compared with field measurements during a controlled drawdown. Field records indicate that classical undrained calculations are conservative but unrealistic. Then, a recent case of a major landslide triggered by a rapid drawdown in a reservoir was interpreted. A key aspect of the case was the correct characterization of permeability of a representative soil profile. This was achieved by combining laboratory test results and a back analysis of pore water pressure time records during a period of reservoir water level fluctuations. The results highlight the difficulty of predicting whether the pore water pressure is overestimated or underestimated when using simplified approaches, and it is concluded that predicting the pore water pressure distribution in a slope after a rapid drawdown requires a coupled flow-deformation analysis in saturated and unsaturated porous media.

Estimating the Lost Economic Production Caused by Internal Displacement Because of Disasters

Disasters are a large cause of internal displacement at the global level, in 2017 alone affecting more than19 million people. This dimension of disaster risk is usually overlooked in many disaster risk management strategies and assessments. It is only very recently that efforts to quantify displacement risk and integrate that dimension into existing physical risk models have been made. A key component of internal displacement assessment is the quantification of its economic impacts, both direct and indirect, not only to make a figure available but to raise awareness and increase accountability among governments, stakeholders, policymakers, and decision makers.This article presents a novel and peril-agnostic methodology with which to estimate, using a scenario-based approach, the economic production lost because of internal population displacement. The methodology is applied by using as a triggering event the April 2015 Gorkha, Nepal M7.8 earthquake. The method quantifies the indirect cost caused by internal population displacement because of that event in terms of lost economic production and estimates the loss to be between USD 400 and 850 million.

Probabilistic Seismic Risk Assessment in Manizales,Colombia: Quantifying Losses for Insurance Purposes

A fully probabilistic seismic risk assessment was developed in Manizales, Colombia, considering assets of different types. The first type includes elements that are part of the water and sewage network, and the second type includes public and private buildings. This assessment required the development of a probabilistic seismic hazard analysis that accounts for the dynamic soil response,assembling high resolution exposure databases, and the development of damage models for different types of elements. The economic appraisal of the exposed assets was developed together with specialists of the water utilities company of Manizales and the city administration. The risk assessment was performed using several Comprehensive Approach to Probabilistic Risk Assessment modules as well as the R-System, obtaining results in terms of traditional metrics such as loss exceedance curve, average annual loss, and probable maximum loss. For the case of pipelines, repair rates were also estimated. The results for the water and sewage network were used in activities related to the expansion and maintenance strategies, as well as for the exploration of financial retention and transfer alternatives using insurance schemes based on technical,probabilistic, and prospective damage and loss estimations.In the case of the buildings, the results were used in the update of the technical premium values of the existing collective insurance scheme.

A coupled fluid FEM-DEM technique for predicting blasting operations in tunnels

We present recent developments in the coupling of the finite element method(FEM)and the discrete element method(DEM)for the analysis of rock blasting operations in tunnels.The coupled FEM-DEM technique has been proven to be an efficient procedure for pre-dicting the multiple fractures of rock induced by the loads generated in blasting.The coupled FEM-DEM procedure is applied in tunnel construction,as well as to gas pressure blasting pyrotechnics to break rocks for the excavation of the tunnel front.In the latter case,the effect of gas explosion is modeled by solving the equations of gas dynamics in the analysis domain using FEM.The effect of gas forces in the underlying rock mass is modeled via an embedded fluid-structure interaction method.The efficiency of the coupled FEM-DEM tech-nique is demonstrated in several examples of fracture tests and rock blasting problems related to tunnel engineering.The examples pre-sented indicate that the combination of the DEM with simple three-node linear triangular elements(for two-dimensional problems)captures the onset of fractures and their evolution accurately,accounting for the penetration of gas in the failure domain(Zarate&Onate,2015;Zarate,Cornejo,&Onate,2018).