Tomorrow’s Cities: Multi-hazard interactions to inform disaster risk reduction in Istanbul

Istanbul is a major global urban centre. With city expansion expected to continue over the next few decades there is a real opportunity for urban growth that incorporates disaster risk reduction (DRR). But in order to develop DRR inclusive urban development strategies we need to understand the breadth of hazards that can affect the city and their potential interactions.

To create a single hazard overview for the city we searched through peer-reviewed literature, reports, government websites and international disaster databases for hazard occurrences. Of the 34 natural hazards in our global hazard table encompassing five major hazard groups (geophysical, shallow process, meteorological, hydrological, climatological and extraterrestrial), we found 27 of these had occurred or had the potential to occur in Istanbul. Notable absences were snow avalanches, glacial outburst floods and direct volcanic hazards. However, ash dispersal models show that ash from volcanic eruptions in the Mediterranean can affect the city.

Additionally, we present an interaction matrix for hazards relevant to the city that shows how one hazard may trigger or increase the probability of another. We adapted the global hazard interaction matrix of Gill and Malamud (2014) by removing hazards that were not relevant to Istanbul and supplementing it with specific examples that have occurred in the city. We found 85 such interactions that reveal the potential for interacting chains of natural hazards.

We discuss how multi-hazard scenarios, developed through expert stakeholder engagement and based on the hazard interaction matrix, are an effective way to explore and communicate the dynamic variability of exposure, vulnerability and therefore, multi-hazard risk.