Paolo Bergamo

Last Name

Bergamo

First Name

Paolo

ORCID

0000-0002-7738-2882

Organisational unit

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

Show all metadata

Search Results

Publications1 - 10 of 34

Systematic assessment of nonlinear soil behavior at KiK-net sites in Japan: Thresholds and controlling site factors
Loviknes, Karina; Bergamo, Paolo; Fäh, Donat; et al. (2025)
Earthquake Spectra
We address two open questions concerning nonlinear soil behavior in a seismic hazard and risk context; (1) which site proxies can be used to predict and map nonlinear site amplification? (2) At which level of ground-motion intensity should such nonlinear models be considered? To answer these questions, we use the KiK-net network in Japan, which includes stations with instruments at both surface and depth, considering events recorded between 1997 and 2024. Using the surface-to-borehole ratio, we systematically capture the empirical effects of nonlinear soil response as the amplitude change and frequency shift between individual events and the linear site response. We then derive station-specific parameters for degree of nonlinearity and threshold for onset of nonlinear behavior. The statistical correlation between nonlinearity and a selection of geotechnical and geological site parameters shows that although parameters characterizing the depth to bedrock and the shallowest part of the soil layer have a promising potential for capturing nonlinear site amplification, the correlation is generally low, suggesting that a single site parameter is not sufficient. As a consistent reference for ground-motion intensity, we empirically calculate PGAemp.rock, as an approximation for PGA recorded on a standard outcropping rock site with VS30 = 760 m/s (average shear-wave velocity of upper 30 m). When analyzing the nonlinear behavior for all recorded events, we define the nonlinear soil behavior as significant when the amplitude change, and frequency shift are greater than 10% for the majority (50%) of the records. We find that in the PGAemp.rock-range 1−3 m/s2 nonlinear soil behavior is significant only for soft soil stations (VS30 < 250 m/s) with intermediate sediment thickness (<30 m). While, according to the mean behavior of all sites, regardless of grouping, nonlinearity is significant only at PGAemp.rock > 3 m/s2. These results show that for nonlinear site-amplification modeling, the onset of nonlinearity is strongly related to the site conditions.
Integrating Seismic Methods for Characterizing and Monitoring Landslides: A Case Study of the Heinzenberg Deep-Seated Gravitational Slope Deformation (Switzerland)
Glueer, Franziska; Mreyen, Anne-Sophie; Cauchie, Léna; et al. (2024)
Geosciences
While geodetic measurements have long been used to assess landslides, seismic methods are increasingly recognized as valuable tools for providing additional insights into subsurface structures and mechanisms. This work aims to characterize the subsurface structures of the deep-seated gravitational slope deformation (DSGSD) at Heinzenberg through the integration of active and passive seismic measurements. Seismic techniques can hereby deliver additional information on the subsurface structure and mechanisms involved, e.g., the degree of rock mass degradation, the resonant frequencies of the potentially unstable compartments, and the local fracture network orientations that are influenced by wavefield polarization. By employing advanced methods such as H/V analysis, site-to-reference spectral ratios, polarization analysis, surface wave analysis, and the joint multizonal transdimensional Bayesian inversion of velocity structures, we establish a comprehensive baseline model of the landslide at five selected sites. This baseline model shall help identify potential changes after the refilling of Lake Lusch, which started in 2021. Our results reveal the rupture surface of the DSGSD at various depths ranging from 30 m at the top to over 90 m in the middle of the slope. Additionally, we estimate key parameters including the shear wave velocities of the different rock masses. The 2D geophysical profiles and rock mass properties contribute to the understanding of the subsurface geometry, geomechanical properties, and potential water pathways. This study demonstrates the significance of integrating seismic methods with traditional geodetic measurements and geomorphologic analysis techniques for a comprehensive assessment of landslides, enhancing our ability to monitor and mitigate hazardous events.
The Earthquake Risk Model of Switzerland, ERM-CH23
Papadopoulos, Athanasios N.; Roth, Philippe; Danciu, Laurentiu; et al. (2024)
Natural Hazards and Earth System Sciences
Understanding seismic risk at both the national and sub-national level is essential for devising effective strategies and interventions aimed at its mitigation. The Earthquake Risk Model of Switzerland (ERM-CH23), released in early 2023, is the culmination of a multidisciplinary effort aiming to achieve for the first time a comprehensive assessment of the potential consequences of earthquakes on the Swiss building stock and population. Having been developed as a national model, ERM-CH23 relies on very high-resolution site-amplification and building exposure datasets, which distinguishes it from most regional models to date. Several loss types are evaluated, ranging from structural-nonstructural and content economic losses to human losses, such as deaths, injuries, and displaced population. In this paper, we offer a snapshot of ERM-CH23, summarize key details on the development of its components, highlight important results, and provide comparisons with other models.
Swiss Shakemap at Fifteen: Distinctive Local Features and International Outreach
Cauzzi, Carlo Virgilio; Clinton, John Francis; Kästli, Philipp; et al. (2022)
Seismological Research Letters
Investigating worldwide strong motion databases to derive a collection of free-field records to select design-compatible waveforms for Switzerland
Panzera, Francesco; Bergamo, Paolo; Danciu, Laurentiu; et al. (2024)
Bulletin of Earthquake Engineering
The process of choosing ground motions typically relies on assembling a collection of ground motions that match a desired spectrum. This selection process is guided by specific seismological criteria, including factors like earthquake magnitude, distance from the epicenter, site soil type, and the range of spectral periods that need to fit with the target spectrum. The selection algorithm and the available dataset of waveforms obviously play significant roles in this process. In many engineering and site response applications, it is essential that the input ground motion is representative for the shaking at the free surface of the Earth, and at times also a specific soil type may be required. However, real waveform databases often lack sufficient and/or consistent metadata related to the installation type and soil characterization of recording stations, as well as to the earthquake seismological parameters. This deficiency can lead to the selection of inappropriate waveforms, such as those recorded by stations situated within manmade structures (buildings, bridges, dams) or on a soil type different than the intended one. To address this issue, our approach for creating an appropriate waveform database applicable to Switzerland starts with the computation of seismic hazard disaggregation for return periods of 475 and 975 years. This computation helps identifying the magnitude-distance scenarios most relevant for the five seismic hazard zones defined in the Swiss building code. Once these magnitude-distance ranges are identified, we adhere to established standards regarding the quality control of three-component waveforms and their associated metadata. We assemble a database of waveforms by collating and homogenizing data from available global databases. In the interest of comprehensiveness, we also incorporate data obtained from 3D physics-based numerical simulations of strong-motion near the seismic source. Finally, we employ an algorithm that integrates the Eurocode 8 waveform selection criteria. This algorithm allows us to select and scale waveforms suitable for microzonation and structural analysis studies within each of Switzerland's five seismic hazard zones. Selecting waveforms compatible with the target design spectra proves to be challenging due to the stringent criteria imposed by Eurocode 8. This challenge arises from the scarcity of recorded waveforms with verified metadata and precise site characterization in the desired magnitude-distance ranges.
The effect of the structure on the earthquake recordings at the seismic borehole array
Janusz, Paulina Agnieszka; Bergamo, Paolo; Fäh, Donat; et al. (2025)
Abstract Volume 23rd Swiss Geoscience Meeting
A scenario-based earthquake loss assessment for Basel
Imtiaz, Afifa; Papadopoulos, Athanasios N.; Bergamo, Paolo; et al. (2023)
Abstract Volume 21st Swiss Geoscience Meeting
A site amplification model for Switzerland based on site-condition indicators and incorporating local response as measured at seismic stations
Bergamo, Paolo; Fäh, Donat; Panzera, Francesco; et al. (2023)
Bulletin of Earthquake Engineering
The spatial estimation of the soil response is one of the key ingredients for the modelling of earthquake risk. We present a ground motion amplification model for Switzerland, developed as part of a national-scale earthquake risk model. The amplification model is based on local estimates of soil response derived for about 240 instrumented sites in Switzerland using regional seismicity data by means of empirical spectral modelling techniques. These local measures are then correlated to continuous layers of topographic and geological soil condition indicators (multi-scale topographic slopes, a lithological classification of the soil, a national geological model of bedrock depth) and finally mapped at the national scale resorting to regression kriging as geostatistical interpolation technique. The obtained model includes amplification maps for PGV (peak ground velocity), PSA (pseudo-spectral acceleration) at periods of 1.0, 0.6 and 0.3 s; the modelled amplification represents the linear soil response, relative to a reference rock profile with VS30 (time-averaged shear-wave velocity in the uppermost 30 m of soil column) = 1105 m/s. Each of these amplification maps is accompanied by two layers quantifying its site-to-site and single-site, within event variabilities, respectively (epistemic and aleatory uncertainties). The PGV, PSA(1.0 s) and PSA(0.3 s) maps are additionally translated to macroseismic intensity aggravation layers. The national-scale amplification model is validated by comparing it with empirical measurements of soil response at stations not included in the calibration dataset, with existing city-scale amplification models and with macroseismic intensity observations from historical earthquakes. The model is also included in the Swiss ShakeMap workflow.
Mapping site amplification with the dense recording of ambient vibration for the city of Lucerne (Switzerland): comparison between two approaches
Janusz, Paulina Agnieszka; Panzera, Francesco; Bergamo, Paolo; et al. (2025)
Bulletin of Earthquake Engineering
Reliable site-specific amplification information can be retrieved using earthquake-based methods that involve the deployment of a permanent (or temporary) network of seismic recording stations. Such an endeavour may need to operate for years, especially within regions of high risk but low recurrence rates in seismic activity. Hence, time- and cost-effective approaches using ambient vibrations are gaining popularity. Among such techniques, the canonical correlation approach (CC) collates measured empirical amplification with its indicator computed from ambient vibrations (i.e. horizontal-to-vertical spectral ratios) for a training set of seismic stations, to predict site response at locations without earthquake recordings. Another method, the hybrid standard spectral ratio method (SSRh) takes advantage of simultaneous recordings of ambient vibrations that are adjusted using earthquake ground motion data using a limited number of instrumented sites to estimate local seismic soil response. We apply both methods in the Lucerne area (Switzerland), which is located on a soft sedimentary basin, and obtain consistent results that are comparable to amplification estimates derived solely from earthquake ground motion data. These results show significant linear amplification factors (8–10 or more) at the fundamental frequency of resonance of the sediments (0.8–2 Hz). However, both techniques show systematic differences in the spatial and frequency domains. The CC method tends to underestimate the amplification at the fundamental frequency, while the SSRh technique predicts higher amplification in the centre of the basin and lower amplification at the basin edges in comparison to the CC approach. The study discusses the impact of the limitations in the completeness of the calibration dataset, and variability introduced by the choice of the shear wave velocity model of the shallow subsurface and inelastic behaviour treatment for the CC method, as well as the influence of the measurement setup for the SSRh method.
Multipath Transfer-Function Correction Method to Predict Site-Specific Amplification at City Scale
Halló, Miroslav; Bergamo, Paolo; Fäh, Donat (2024)
Seismological Research Letters
The site-specific amplification of seismic waves is an essential component of local seismic hazard assessment. It can be evaluated from empirical data, but measurements are feasible just in a limited number of locations. Hence, at the city scale, there is a need for the theoretical prediction and interpolation of the amplification. In this article, we introduce a physics-based method to predict the site-specific amplification and duration in a broad frequency range. The method is based on a novel energy-based concept of the multipath propagation of waves in viscoelastic media with random heterogeneities. The amplification is expressed by the surface-outcrop transfer function of the multipath wave propagation, which is defined by expected values of the energy spectral ratio. The method is applied to the near-surface 2D velocity model in the city of Zürich in Switzerland. The predicted amplification is validated by empirical data at a nearby seismic station, and it is compared with the soil class and other site-condition proxies. Finally, the method performance is demonstrated by the prediction of site-specific seismic waveforms and response spectra for the 2022 ML 4.7 Mulhouse earthquake.

Publications1 - 10 of 34

Paolo Bergamo

Last Name

First Name

ORCID

Organisational unit

Filters

Search Results