Laurentiu Danciu

Last Name

Danciu

First Name

Laurentiu

ORCID

0000-0003-4086-8755

Organisational unit

02818 - Schweiz. Erdbebendienst (SED) / Swiss Seismological Service (SED)

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Publications 1 - 10 of 70

Comparison between outcomes of the 2014 Earthquake Hazard Model of the Middle East (EMME14) and national seismic design codes: The case of Iran
Kohrangi, Mohsen; Danciu, Laurentiu; Bazzurro, Paolo (2018)
Soil Dynamics and Earthquake Engineering
Methods for evaluating the significance and importance of differences amongst probabilistic seismic hazard results for engineering and risk analyses: a review and insights
Douglas, John; Crowley, Helen; Silva, Vitor; et al. (2024)
Bulletin of Earthquake Engineering
When new seismic hazard estimates are published it is natural to compare them to existing results for the same location. This type of comparison routinely indicates differences amongst hazard estimates obtained with the various models. The question that then arises is whether these differences are scientifically significant, given the large epistemic uncertainties inherent in all seismic hazard estimates, or practically important, given the use of hazard models as inputs to risk and engineering calculations. A difference that exceeds a given threshold could mean that building codes may need updating, risk models for insurance purposes may need to be revised, or emergency management procedures revisited. In the current literature there is little guidance on what constitutes a significant or important difference, which can lead to lengthy discussions amongst hazard modellers, end users and stakeholders. This study reviews proposals in the literature on this topic and examines how applicable these proposals are, using, for illustration purposes, several sites and various seismic hazard models for each site, including the two European Seismic Hazard Models of 2013 and 2020. The implications of differences in hazard for risk and engineering purposes are also examined to understand how important such differences are for potential end users of seismic hazard models. Based on this, we discuss the relevance of such methods to determine the scientific significance and practical importance of differences between seismic hazard estimates and identify some open questions. We conclude that there is no universal criterion for assessing differences between seismic hazard results and that the recommended approach depends on the context. Finally, we highlight where additional work is required on this topic and that we encourage further discussion of this topic.
The role of modelling of site conditions and amplification in seismic hazard and risk assessment at urban scale. The case of Thessaloniki, Greece
Riga, Evi; Apostolaki, Stefania; Karatzetzou, Anna; et al. (2022)
Italian Journal of Geosciences
One of the main challenges of large-scale seismic hazard and risk applications is the characterization of the amplification of seismic ground motion due to the local site conditions, often described by Vs,30, i.e., the timeaveraged shear wave velocity in the upper 30 meters of the soil deposit. In most of these applications, Vs,30 values are directly estimated from microzonation investigations, inferred from proxies such as the topographic slope, or obtained from seismic codes based on a simplified site categorization. The scope of this work is to investigate the effects of the method applied for modelling of site conditions and site amplification in urban risk assessment. For this we consider the application of the 2020 updates of the European Seismic Hazard (ESHM20) and Risk (ESRM20) Models and we focus on Thessaloniki, Greece, a city which is very well documented in terms of both local site conditions and exposure. To this end, we compare seismic hazard and risk results obtained using two different approaches for site conditions / site amplification modelling. In the first approach, which may be considered as more rigorous but also more demanding, two different appropriate site condition models are directly used in the ESHM20 hazard logic tree. In the second approach, which is more simplified and efficient in practice, two site amplification models were developed for the study area based on the soil classification according to two different code-oriented classification schemes. Eventually, four hazard models are obtained. Seismic risk results are presented in terms of expected damages and economic losses for a seismic hazard with a 475-year return period. Both hazard and risk assessment calculations are undertaken with the OpenQuake Engine (Pagani et al., 2014; Silva et al., 2014). The main conclusion for the case of Thessaloniki is that, for the given fragility and vulnerability models, the estimated aggregate damages and economic losses at city scale are not significantly affected by the way that local site conditions are taken into account, which indicates that simplified approaches for site modelling may be used for large scale applications when more rigorous approaches are not feasible. Significant discrepancies may occur, however, at local scale.
European Seismic Risk Model - Insights and Emerging Research Topics
Crowley, Helen; Dabbeek, Jamal; Despotaki, Venetia; et al. (2022)
Springer Proceedings in Earth and Environmental Sciences ~ Progresses in European Earthquake Engineering and Seismology
A new European Seismic Risk Model (ESRM20) was recently released to the scientific community (http://risk.efehr.org). This model combines the European Seismic Hazard Model (ESHM20), a regional model of site response based on proxy data (topography and geology), an exposure model describing the distribution of building classes for 44 countries, and vulnerability models for over 200 building classes, in order to estimate key seismic risk metrics at the European scale, including average annual losses and return period economic losses and loss of life. This Chapter explores some of the insights from this model, including the regions of highest risk in Europe, the building classes contributing most to the losses, and the potential impact of retrofitting those building classes. All of the models, as well as the underlying datasets, workflows and software have been openly released, thus allowing reproducibility of the results, but also providing a set of resources that can be used to kick-start additional research. Examples of how these resources can be used by researchers will be given herein, as well as new research topics emerging from the models.
Subaqueous landslide-triggered tsunami hazard for Lake Zurich, Switzerland
Strupler, Michael; Hilbe, Michael; Kremer, Katrina; et al. (2018)
Swiss Journal of Geosciences
Subaqueous landslides can induce potentially damaging tsunamis. Tsunamis are not restricted to the marine environment, but have also been documented on lakes in Switzerland and worldwide. For Lake Zurich (central Switzerland), previous work documented multiple, assumedly earthquake-triggered landslides. However, no information about past tsunamis is available for Lake Zurich. In a back-analysis, we model tsunami scenarios as a consequence of the earthquake-triggered landslides in the past. Furthermore, on the basis of a recent map of the earthquake-triggered subaqueous landslide hazard, we present results of a tsunami hazard assessment. The subaqueous landslide progression, wave propagation and inundation are calculated with a combination of open source codes. Although no historic evidence of past tsunamis has been documented for Lake Zurich, a tsunami hazard exists. However, only earthquakes with long return periods are assumed to cause considerable tsunamis. An earthquake with an exceedance probability of 0.5% in 50 years (corresponding to an earthquake with a return period of 9975 years) is assumed to cause tsunamigenic landslides on most lateral slopes of Lake Zurich. A hypothetical tsunami for such an event would create damage especially along the shores of the central basin of Lake Zurich with estimated peak flow depths of up to ~ 4.6 m. Our results suggest that for an earthquake with an exceedance probability of 10% in 50 years (i.e., mean return period of 475 years), no considerable tsunami hazard is estimated. Even for a worst-case scenario, the cities of Zurich and Rapperswil, located at the northern and southern ends of the lake, respectively, are assumed to experience very little damage. The presented first-order results of estimated wave heights and inundated zones provide valuable information on tsunami-prone areas that can be used for further investigations and mitigation measures.
A framework to quantify the effectiveness of earthquake early warning in mitigating seismic risk
Papadopoulos, Athanasios N.; Böse, Maren; Danciu, Laurentiu; et al. (2023)
Earthquake Spectra
Earthquake early warning systems (EEWSs) aim to rapidly detect earthquakes and provide timely alerts, so that users can take protective actions prior to the onset of strong ground shaking. The promise and limitations of EEWSs have both been widely debated. On one hand, an operational EEWS could mitigate earthquake damage by triggering potentially cost- and life-saving actions. These range from automated system responses such as slowing down trains to the actions of individuals that receive the alerts and take protective measures. On the other hand, the effectiveness of an EEWS is conditional on the ability to issue warnings that are sufficiently accurate and timely to facilitate an appropriate action. The refinement of earthquake early warning (EEW) algorithms and the installation of denser and faster seismic networks have improved performance; however, the benefit in risk reduction that an EEWS could achieve remains unquantified. In this study, we leverage upon regional event-based probabilistic seismic risk assessment to devise a quantitative and fully customizable framework for evaluating the effectiveness of EEW in mitigating seismic risk. We demonstrate this framework using Switzerland as a testbed, for which we compute and contrast human loss exceedance curves with and without EEW.
Towards a dynamic earthquake risk framework for Switzerland
Böse, Maren; Danciu, Laurentiu; Papadopoulos, Athanasios N.; et al. (2024)
Natural Hazards and Earth System Sciences
Scientists from different disciplines at ETH Zurich are developing a dynamic, harmonised, and user-centred earthquake risk framework for Switzerland, relying on a continuously evolving earthquake catalogue generated by the Swiss Seismological Service (SED) using the national seismic networks. This framework uses all available information to assess seismic risk at various stages and facilitates widespread dissemination and communication of the resulting information. Earthquake risk products and services include operational earthquake (loss) forecasting (OE(L)F), earthquake early warning (EEW), ShakeMaps, rapid impact assessment (RIA), structural health monitoring (SHM), and recovery and rebuilding efforts (RRE). Standardisation of products and workflows across various applications is essential for achieving broad adoption, universal recognition, and maximum synergies. In the Swiss dynamic earthquake risk framework, the harmonisation of products into seamless solutions that access the same databases, workflows, and software is a crucial component. A user-centred approach utilising quantitative and qualitative social science tools like online surveys and focus groups is a significant innovation featured in all products and services. Here we report on the key considerations and developments of the framework and its components. This paper may serve as a reference guide for other countries wishing to establish similar services for seismic risk reduction.
The 2020 European Seismic Hazard Model: overview and results
Danciu, Laurentiu; Giardini, Domenico; Weatherill, Graeme; et al. (2024)
Natural Hazards and Earth System Sciences
The 2020 update of the European Seismic Hazard Model (ESHM20) is the most recent and up-to-date assessment of seismic hazard for the Euro-Mediterranean region. The new model, publicly released in May 2022, incorporates refined and cross-border harmonized earthquake catalogues, homogeneous tectonic zonation, updated active fault datasets and geological information, complex subduction sources, updated area source models, a smoothed seismicity model with an adaptive kernel optimized within each tectonic region, and a novel ground motion characteristic model. ESHM20 supersedes the 2013 European Seismic Hazard Model (ESHM13; Woessner et al., 2015) and provides full sets of hazard outputs such as hazard curves, maps, and uniform hazard spectra for the Euro-Mediterranean region. The model provides two informative hazard maps that will serve as a reference for the forthcoming revision of the European Seismic Design Code (CEN EC8) and provides input to the first earthquake risk model for Europe (Crowley et al., 2021). ESHM20 will continue to evolve and act as a key resource for supporting earthquake preparedness and resilience throughout the Euro-Mediterranean region under the umbrella of the European Facilities for Seismic Hazard and Risk consortium (EFEHR Consortium).
Mapping Europe's seismic hazard
Giardini, Domenico; Wössner, Jochen; Danciu, Laurentiu (2014)
EOS
From the rift that cuts through the heart of Iceland to the complex tectonic convergence that causes frequent and often deadly earthquakes in Italy, Greece, and Turkey to the volcanic tremors that rattle the Mediterranean, seismic activity is a prevalent and often life‐threatening reality across Europe. Any attempt to mitigate the seismic risk faced by society requires an accurate estimate of the seismic hazard.
Reassessment of the Maximum Fault Rupture Length of Strike-Slip Earthquakes and Inference on M-max in the Anatolian Peninsula, Turkey
Mignan, Arnaud; Danciu, Laurentiu; Giardini, Domenico (2015)
Seismological Research Letters

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