Novel approaches to building disaster risk preparedness: IIASA develops scenario tools for vulnerability analysis and mitigation

The Vulnerability Analysis and Assessment (VAA) tool of CAT-ASA group at IIASA, is among the core methodologies of the PARATUS project. The tool combines statistical and machine learning methods with scenario-based planning to generate detailed vulnerability profiles. These profiles integrate multiple dimensions—including spatio-temporal patters of cascading-hazards, physical exposures of buildings and infrastructure, socio-economic and environmental factors such as, for example, income, access to social and healthcare provision, resources availability. As a result, the VAA profiling assists optimization-based development planning for systemic risk and vulnerability mitigation.

Bucharest: Cascading Risk due to Earthquakes in an Aging City

One of the most earthquake-prone capitals in Europe is Bucharest, with many historic and structurally weak buildings located in densely populated districts. An earthquake, as primary event, can trigger secondary cascading risks due to dams’ breaks, critical infrastructures failures, roads blockages and other, PARATUS project not only highlights the earthquake risks, as traditional studies do, but also advances the analysis by exploring scenarios of current and plausible future interdependent risks and vulnerabilities. Namely, using the VAA tool, researchers can explore how vulnerabilities may change depending on revised vulnerability drivers, i.e., implementation of stricter building codes, large-scale retrofitting programs, or relocation of vulnerable populations and economic activities away from risk-prone areas. These scenario analyses help decision-makers test the effectiveness of different ex ante precautionary and ex-post reconstruction (Building-Back-Better) policies thereby ensuring that resources are directed to the most impactful measures.

Istanbul: Multiple Hazards in a Growing Megacity

The city of Istanbul, with a population of over 10 million people, presents a different but equally pressing challenge. The city experiences rapid urban growth and expansion, while being exposed to frequent earthquakes, floods and consequent cascading failures connected, e.g., with NaTech risks (defined as compound hazards from natural and technological risks). This combination can result in catastrophic impacts on people, housing, infrastructure, production, and logistics.

The VAA tool is being applied at the level of Istanbul neighborhoods to show how vulnerabilities change depending on feasible urban development planning policy choices. For example, constructing new housing in safer zones, improving access to open spaces, or reinforcing critical infrastructure - all these policies can lead to different safety and resilience outcomes. By modeling the policies, the tool provides decision-makers with practical insights into how to guide city development planning in Istanbul in a way that can decrease potential losses and strengthen disaster resilience.

Advancing Risk Governance Approaches

Beyond these two case studies, the approach demonstrates how quantitative modeling can be linked with stakeholder engagement to improve disaster risk governance. By integrating future scenarios, socio-economic data, and advanced modeling techniques such as Principal Component Analysis (PCA), Analytical Hierarchy Process (AHP) methods, and quantile-based statistical and machine learning, PARATUS enables authorities to move from reactive ex-post crisis management to proactive ex-ante precautionary planning.

These advances mark a significant step forward in disaster risk management in Europe and beyond. With tools like the VAA, policymakers are better equipped to understand not only where risks are located today, but also how the implementation of feasible policies now can reshape vulnerabilities and resilience in the decades to come.