Multi-risk estimation through Impact Chains, earthquake and flood loss simulations. Progress for Bucharest Case Study within the PARATUS and MULTICARE Projects.

Bucharest can be considered Europe's most endangered capital to earthquakes. Intermediate-depth seismic events occurring in the Vrancea Area, with magnitudes greater than 7 M_W, can significantly affect the city. In the 20th century, Bucharest experienced two major damaging earthquakes: in 1940 and 1977. But the occasioned lessons were not fully learned. The number of vulnerable buildings is nowadays considerable, as over 30% of them were built before 1963 (of which 22%, before 1941). New factors among which climate change, increased exposure, and road congestion, alongside perpetuated or augmented vulnerabilities of different types, can contribute to higher than ever losses. In this context, new ways of quantifying the impacts are necessary.

Within the PARATUS and MULTICARE EU Projects, we started a complex evaluation of multi-risk centered around multi-hazard scenarios relevant to Bucharest. Beside earthquakes, we also looked at the potential effects of a dam break and levee breach for the Morii Lake located in the north-western part of the city, upstream of the city center. To explain the intricate interplay among cascading hazards, exposure, and vulnerability, first of all we developed an Impact Chain for the present and future situation, integrating a wide range of feedback from relevant stakeholders (i.e., decision-makers, first and second responders, military, architects, academics, insurance companies, legal experts).

To support loss estimation and the evaluation of flood propagation, we developed a new exposure and vulnerability database at the building level. In our presentation, we will detail the data collection process involving satellite images (including from the KH-9 mission in the 70’s and 80’s), deep learning algorithms, open-source and census data, or evaluations of individual buildings conducted by engineers and architects. This database allowed us to run OpenQuake for a near-real time estimation of seismic losses, proving to be highly valuable for first-responders but also for developing scenario-driven preparedness plans. A fully 2D modelling approach was used for the flood hazard analysis aiming to determine the flooded areas and maximum water height, accounting for the resistance imposed to the water flow by buildings.

In order to highlight the importance of road network functionality given various seismic and flood scenarios, we also performed an evaluation of travel-time estimation, at the city level. For this, factored in incidents (such as road blockage due to debris, bridge collapse, or access restrictions caused by flooding) and their impacts on traffic at particular times. The analysis also reveals the importance of dedicated lanes for first response vehicles, currently delimited in Bucharest on tramway lines. Future research initiatives focus on 1) evaluating accessibility to hospitals, considering also their capacity of treating different types of patients and 2) proposing improvements in road network planning and hospital location, grounded on the obtained expected distribution of losses.