Dragos Toma-Danila

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 MW, 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.

In the last years, the impacts of natural hazards have been coupled with and sometimes overshadowed by those of the COVID-19 pandemic. Such co-occurrences added extra layers to risk management and highlighted the need for updated multi-hazard risk models and management plans. While developing the tools, models, and strategies to battle the challenges of the post-pandemic world, an unsettling question lingers: What if the most impactful and feared hazard in a specific area were to occur during a pandemic wave?This study aims to 1) take an in-depth look at the impact of the COVID-19 pandemic on the hospital system in Bucharest, Romania, and 2) identify the compounded impacts of a powerful earthquake that would potentially affect the city during a pandemic wave, under an Impact Chain-based approach. To this end, two Impact Chains are analysed side by side: one of them presents the actual impacts of the pandemic documented for 2020-2022, and the other focuses on the potential impacts of a powerful earthquake, similar to the one that affected Romania in March 1977 (7.4 MW). The co-occurrence of such powerful hazardous events poses a worst-case scenario for Bucharest, which stands out as the European capital with the highest seismic risk and one of the urban centres severely affected by the COVID-19 pandemic. The Impact Chain centred on the COVID-19 pandemic dwells on a wide range of sources: scientific literature, data collected from hospital administration (e.g., reports on available medical resources, including human resources), official reports from international health care organisms, legislative documents that regulate COVID-19 prevention protocols, official press releases, and grey literature in the form of news reports. The earthquake-based Impact Chain represents a simplified, expert knowledge-based version of a larger chain developed within the Paratus Project as part of the analysis of present and future outcomes of a major earthquake in Bucharest. By juxtaposing the two Impact Chains, this study addresses the research gap concerning the compounded impacts of earthquakes and the COVID-19 pandemic, an area currently open for further investigation. This analysis offers an initial answer to the worrisome question posed earlier, aiding in the preparation for “the worst” in Bucharest.Keywords: COVID-19 pandemic, earthquake, impact chain, hospital system, Romania

Evaluating the performance of probabilistic seismic hazard models against recorded data and their potential to forecast future earthquake ground shaking is an emerging research topic. In this study, we evaluate and test the results of the recently released 2020 European Seismic Hazard Model (ESHM20; Danciu et al., 2021a, 2024) against observations for several cities in Romania. The dataset consists of ground-shaking recordings and macroseismic observations that extend the observational time period to a few hundred years. The full distribution of the hazard curves, depicting the epistemic uncertainties in the hazard at the given location was considered, and the testing was performed for peak ground acceleration (PGA) values of 0.1 and 0.2 g. The results show consistency between ESHM20 and the ground motion observations for the cities located near the Vrancea intermediate-depth source (VRI) for both selected PGA levels. ESHM20's estimated values appear to be over the recorded VRI ground motions along the Carpathian Mountains and below those at the far-field locations outside the Carpathians yet inside the expected model variability. Some of these differences might be attributed to the uncertainties in data conversion, local site effects, or differences in the attenuation patterns of the ground motion models. Our analysis suggests that the observed exceedance rates for the selected PGA levels are consistent with ESHM20 estimates, but these results must be interpreted with caution given the limited time and spatial coverage of the observations.

In the present study, an effort to propose and adopt appropriate Ground Motion Prediction Equations (GMPEs) for the Rapid Earthquake Damage Assessment System (REDAS) in the Black Sea basin is attempted. Emphasis of GMPE harmonization in the cross-border areas (CBA) is given. For this reason, two distinct sub-areas are investigated, taking into consideration their seismotectonic regime. One sub-area refers to active shallow crustal earthquakes (Greece-Turkey, CBA) and the other to intermediate-depth and shallow crustal earthquakes (Romania-Moldova, Western Black Sea CBA). Testing and ranking of pre-selected GMPEs has been performed using strong motion data of the broader CBA regions of both sub-areas. The final proposed GMPEs to feed the REDA System may assure the effective estimation of ShakeMaps and—in combination with the appropriate vulnerability curves—reliable near-real-time damage assessment in the cross-border earthquake affected areas.

Evaluating the performance of probabilistic seismic hazard models against recorded data and their potential to forecast future earthquake’s ground shaking is an emerging research topic. In this study, we evaluate and test the results of the recently released European Seismic Hazard Model (ESHM20; Danciu et al., 2021) against observations for several cities in Romania. The dataset consists of ground shaking recordings and macroseismic observations, which extend the observational time-period to few hundred years. The full distribution of the hazard curves, depicting the epistemic uncertainties of the hazard at the given location was considered and the testing was done for peak ground acceleration (PGA) values i.e., 0.1 g and 0.2 g. The results show close agreement between the ESHM20 and the observations for the cities located near the Vrancea intermediate-depth source (VRI) for both selected PGA levels. ESHM20 appears to overestimate the VRI recorded ground motions along the Carpathian Mountain Range and underestimate those at the far-field locations outside the Carpathians. Some of these differences might be attributed to the uncertainties in data conversion, local site effects, or differences in the attenuation patterns of the ground motion models. Our analysis suggests that the observed exceedance rates for the selected PGA levels are consistent with ESHM20 estimates, but these results must be interpreted with caution given the limited time and spatial coverage of the observations.

Bucharest can be considered Europe's most endangered capitals due to earthquakes. Intermediate-depth events occurring in the Vrancea Area, with magnitudes greater than 7, can significantly affect Bucharest. In the XXth century, the city experienced two major damaging earthquakes: in 1940 and 1977. But lessons were not fully learned. The number of vulnerable buildings is highly considerable: over 30% are built before 1963 (of which 22%, before 1941). The increased complexity of our society and new challenges among which climate change, pandemics and globalization are new problems to address. In this context, multi-hazard and multi-risk analyses are more than ever necessary.If the 1977 earthquake generated numerous research with the aim of quantifying the vulnerability of the building stock and improving seismic design, social vulnerability to seismic risk was addressed only after 2000 by the Risk Research Center, University of Bucharest, based on a repeated spatial vulnerability assessment at city-level. Applying the additive approach of the multi-criteria and decision-making analysis in GIS, the spatial social vulnerability was identified by indicators of social and economic metrics, among which social capital and inequality, distance analysis, and on empirical taxonomies: gender, age, social status, ethnicity, type of housing, etc., based on 1992, 2002 and 2011 census data. Calibrating results using remote sensing and social surveys, helped identify vulnerable hotspots and the dynamic of social differences at city level. Superimposed on these detailed vulnerability maps for Bucharest based on computed vulnerability indices, a critical decision-making tool for safe access routes in the emergency intervention was developed supported by large sets of traffic and network data, time-dependent analysis, and seismic loss-estimations. This tool, called Network-Risk, uses a state-of-the-art network analysis methodology embedded in GIS, with the potential of integrating live traffic data.All these topics will be continued in the recently started PARATUS European Project, where Bucharest is a case-study area. In our presentation, we talk about the new data and procedures that we consider for seismic risk assessment (among which new exposure data from a recent census or retrieved from remote sensing missions using deep learning, new data collecting procedures, vulnerability models and city-scale ShakeMap development) and which are the challenges – especially in the nowadays context.

The Internet of things concept empowered by low-cost sensor technologies and headless computers has upscaled the applicability of vibration monitoring systems in recent years. Raspberry Shake devices are among those systems, constituting a crowdsourcing framework and forming a worldwide seismic network of over a thousand nodes. While Raspberry Shake devices have been proven to densify seismograph arrays efficiently, their potential for structural health monitoring (SHM) is still unknown and is open to discovery. This paper presents recent findings from existing buildings located in Bucharest (Romania) equipped with Raspberry Shake 4D (RS4D) devices, whose signal recorded under multiple seismic events has been analyzed using different modal identification algorithms. The obtained results show that RS4D modules can capture the building vibration behavior despite the short-duration and low-amplitude excitation sources. Based on 15 RS4D device readings from five different multistorey buildings, the results do not indicate damage in terms of modal frequency decay. The findings of this research propose a baseline for future seismic events that can track the changes in vibration characteristics as a consequence of future strong earthquakes. In summary, this research presents multi-device, multi-testbed, and multi-algorithm evidence on the feasibility of RS4D modules as SHM instruments, which are yet to be explored in earthquake engineering.

Earthquakes can generate a significant number of casualties within seconds, as well as high economic losses. The lack of rapid and coordinated emergency intervention can contribute to much greater losses. In this paper we develop a framework taking advantage of the ArcGis Network Analyst extension, able to account for post-earthquake conditions and reflect travel times. By combining 1) network characteristics with 2) direct seismic damage information, 3) models to determine road obstruction potential, 4) traffic information and time-dependent post-earthquake modeling but also 5) emergency intervention facilities (hospitals or fire stations) and considerations regarding their functional limitations, this framework can provide important support for the management of emergency intervention but also for risk reduction planning. Main results consist of maps showing travel times for various scenarios and moments after an earthquake, inaccessible areas, vital roads for access or an identification of important facilities. As case study we chose Bucharest, one of Europe’s most endangered capitals considering the seismic risk level. The city was and could be considerably affected by earthquakes in the Vrancea Seismic Zone, being characterized by a high number of vulnerable buildings and by one of the greatest typical traffic congestion levels in the world. Compared to previous network studies for Bucharest, the new approach is more complex and customable, providing means for real-time integration and time-dependent analysis. Results, for a worst-case scenario, prove that the risks could be even greater than expected, but also what should be done to mitigate them, such as the construction of a new hospital in the western part of the city, ensuring safe delimited routes for emergency vehicles or expanding the treatment capacity of actual hospitals—some of which also need seismic retrofitting. Results of this study will be integrated in the revised version of the National Conception for Post-Earthquake Response—an operational framework which will lead to risk mitigation through the improvement of post-disaster reaction.