TY - JOUR A1 - Chen, Yen-Shin A1 - Weatherill, Graeme A1 - Pagani, Marco A1 - Cotton, Fabrice Pierre T1 - A transparent and data-driven global tectonic regionalization model for seismic hazard assessment JF - Geophysical journal international N2 - A key concept that is common to many assumptions inherent within seismic hazard assessment is that of tectonic similarity. This recognizes that certain regions of the globe may display similar geophysical characteristics, such as in the attenuation of seismic waves, the magnitude scaling properties of seismogenic sources or the seismic coupling of the lithosphere. Previous attempts at tectonic regionalization, particularly within a seismic hazard assessment context, have often been based on expert judgements; in most of these cases, the process for delineating tectonic regions is neither reproducible nor consistent from location to location. In this work, the regionalization process is implemented in a scheme that is reproducible, comprehensible from a geophysical rationale, and revisable when new relevant data are published. A spatial classification-scheme is developed based on fuzzy logic, enabling the quantification of concepts that are approximate rather than precise. Using the proposed methodology, we obtain a transparent and data-driven global tectonic regionalization model for seismic hazard applications as well as the subjective probabilities (e.g. degree of being active/degree of being cratonic) that indicate the degree to which a site belongs in a tectonic category. KW - Fuzzy logic KW - Earthquake hazards KW - Seismicity and tectonic Y1 - 2018 U6 - https://doi.org/10.1093/gji/ggy005 SN - 0956-540X SN - 1365-246X VL - 213 IS - 2 SP - 1263 EP - 1280 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Weatherill, Graeme A1 - Kotha, Sreeram Reddy A1 - Cotton, Fabrice Pierre T1 - Re-thinking site amplification in regional seismic risk assessment JF - Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute N2 - Probabilistic assessment of seismic hazard and risk over a geographical region presents the modeler with challenges in the characterization of the site amplification that are not present in site-specific assessment. Using site-to-site residuals from a ground motion model fit to observations from the Japanese KiK-net database, correlations between measured local amplifications and mappable proxies such as topographic slope and geology are explored. These are used subsequently to develop empirical models describing amplification as a direct function of slope, conditional upon geological period. These correlations also demonstrate the limitations of inferring 30-m shearwave velocity from slope and applying them directly into ground motion models. Instead, they illustrate the feasibility of deriving spectral acceleration amplification factors directly from sets of observed records, which are calibrated to parameters that can be mapped uniformly on a regional scale. The result is a geologically calibrated amplification model that can be incorporated into national and regional seismic hazard and risk assessment, ensuring that the corresponding total aleatory variability reflects the predictive capability of the mapped site proxy. KW - earthquake hazard analysis KW - ground motion KW - seismic risk KW - site effects KW - regional mapping Y1 - 2020 U6 - https://doi.org/10.1177/8755293019899956 SN - 8755-2930 SN - 1944-8201 VL - 36 IS - 1_SUPPL SP - 274 EP - 297 PB - Sage Publishing CY - Thousand Oaks, CA ER - TY - JOUR A1 - Weatherill, Graeme A1 - Cotton, Fabrice Pierre T1 - A ground motion logic tree for seismic hazard analysis in the stable cratonic region of Europe BT - regionalisation, model selection and development of a scaled backbone approach JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - Regions of low seismicity present a particular challenge for probabilistic seismic hazard analysis when identifying suitable ground motion models (GMMs) and quantifying their epistemic uncertainty. The 2020 European Seismic Hazard Model adopts a scaled backbone approach to characterise this uncertainty for shallow seismicity in Europe, incorporating region-to-region source and attenuation variability based on European strong motion data. This approach, however, may not be suited to stable cratonic region of northeastern Europe (encompassing Finland, Sweden and the Baltic countries), where exploration of various global geophysical datasets reveals that its crustal properties are distinctly different from the rest of Europe, and are instead more closely represented by those of the Central and Eastern United States. Building upon the suite of models developed by the recent NGA East project, we construct a new scaled backbone ground motion model and calibrate its corresponding epistemic uncertainties. The resulting logic tree is shown to provide comparable hazard outcomes to the epistemic uncertainty modelling strategy adopted for the Eastern United States, despite the different approaches taken. Comparison with previous GMM selections for northeastern Europe, however, highlights key differences in short period accelerations resulting from new assumptions regarding the characteristics of the reference rock and its influence on site amplification. KW - ground motion models KW - stable craton KW - regionalisation KW - epistemic KW - uncertainty KW - Europe Y1 - 2020 U6 - https://doi.org/10.1007/s10518-020-00940-x SN - 1570-761X SN - 1573-1456 VL - 18 IS - 14 SP - 6119 EP - 6148 PB - Springer Science + Business Media B.V. CY - Dordrecht ER - TY - JOUR A1 - Nievas, Cecilia A1 - Pilz, Marco A1 - Prehn, Karsten A1 - Schorlemmer, Danijel A1 - Weatherill, Graeme A1 - Cotton, Fabrice T1 - Calculating earthquake damage building by building BT - the case of the city of Cologne, Germany JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - The creation of building exposure models for seismic risk assessment is frequently challenging due to the lack of availability of detailed information on building structures. Different strategies have been developed in recent years to overcome this, including the use of census data, remote sensing imagery and volunteered graphic information (VGI). This paper presents the development of a building-by-building exposure model based exclusively on openly available datasets, including both VGI and census statistics, which are defined at different levels of spatial resolution and for different moments in time. The initial model stemming purely from building-level data is enriched with statistics aggregated at the neighbourhood and city level by means of a Monte Carlo simulation that enables the generation of full realisations of damage estimates when using the exposure model in the context of an earthquake scenario calculation. Though applicable to any other region of interest where analogous datasets are available, the workflow and approach followed are explained by focusing on the case of the German city of Cologne, for which a scenario earthquake is defined and the potential damage is calculated. The resulting exposure model and damage estimates are presented, and it is shown that the latter are broadly consistent with damage data from the 1978 Albstadt earthquake, notwithstanding the differences in the scenario. Through this real-world application we demonstrate the potential of VGI and open data to be used for exposure modelling for natural risk assessment, when combined with suitable knowledge on building fragility and accounting for the inherent uncertainties. KW - Building exposure modelling KW - Seismic damage assessment KW - Scenario KW - earthquake KW - Seismic risk KW - Cologne Y1 - 2022 U6 - https://doi.org/10.1007/s10518-021-01303-w SN - 1570-761X SN - 1573-1456 VL - 20 IS - 3 SP - 1519 EP - 1565 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Türker, Elif A1 - Cotton, Fabrice A1 - Pilz, Marco A1 - Weatherill, Graeme T1 - Analysis of the 2019 Mw 5.8 Silivri earthquake ground motions BT - evidence of systematic azimuthal variations associated with directivity effects JF - Seismological research letters N2 - The main Marmara fault (MMF) extends for 150 km through the Sea of Marmara and forms the only portion of the North Anatolian fault zone that has not ruptured in a large event (Mw >7) for the last 250 yr. Accordingly, this portion is potentially a major source contributing to the seismic hazard of the Istanbul region. On 26 September 2019, a sequence of moderate-sized events started along the MMF only 20 km south of Istanbul and were widely felt by the population. The largest three events, 26 September Mw 5.8 (10:59 UTC), 26 September 2019 Mw 4.1 (11:26 UTC), and 20 January 2020 Mw 4.7 were recorded by numerous strong-motion seismic stations and the resulting ground motions were compared to the predicted means resulting from a set of the most recent ground-motion prediction equations (GMPEs). The estimated residuals were used to investigate the spatial variation of ground motion across the Marmara region. Our results show a strong azimuthal trend in ground-motion residuals, which might indicate systematically repeating directivity effects toward the eastern Marmara region. Y1 - 2022 U6 - https://doi.org/10.1785/0220210168 SN - 0895-0695 SN - 1938-2057 VL - 93 IS - 2A SP - 693 EP - 705 PB - Seismological Society of America CY - Boulder, Colo. ER - TY - GEN A1 - Pilz, Marco A1 - Cotton, Fabrice Pierre A1 - Razafindrakoto, Hoby Njara Tendrisoa A1 - Weatherill, Graeme A1 - Spies, Thomas T1 - Regional broad-band ground-shaking modelling over extended and thick sedimentary basins BT - An example from the Lower Rhine Embayment (Germany) T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The simulation of broad-band (0.1 to 10 + Hz) ground-shaking over deep and spatially extended sedimentary basins at regional scales is challenging. We evaluate the ground-shaking of a potential M 6.5 earthquake in the southern Lower Rhine Embayment, one of the most important areas of earthquake recurrence north of the Alps, close to the city of Cologne in Germany. In a first step, information from geological investigations, seismic experiments and boreholes is combined for deriving a harmonized 3D velocity and attenuation model of the sedimentary layers. Three alternative approaches are then applied and compared to evaluate the impact of the sedimentary cover on ground-motion amplification. The first approach builds on existing response spectra ground-motion models whose amplification factors empirically take into account the influence of the sedimentary layers through a standard parameterization. In the second approach, site-specific 1D amplification functions are computed from the 3D basin model. Using a random vibration theory approach, we adjust the empirical response spectra predicted for soft rock conditions by local site amplification factors: amplifications and associated ground-motions are predicted both in the Fourier and in the response spectra domain. In the third approach, hybrid physics-based ground-motion simulations are used to predict time histories for soft rock conditions which are subsequently modified using the 1D site-specific amplification functions computed in method 2. For large distances and at short periods, the differences between the three approaches become less notable due to the significant attenuation of the sedimentary layers. At intermediate and long periods, generic empirical ground-motion models provide lower levels of amplification from sedimentary soils compared to methods taking into account site-specific 1D amplification functions. In the near-source region, hybrid physics-based ground-motions models illustrate the potentially large variability of ground-motion due to finite source effects. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1371 KW - ground-motion modelling KW - site effects KW - scenario KW - random vibration KW - theory KW - hybrid modelling Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-571655 SN - 1866-8372 IS - 2 ER - TY - JOUR A1 - Lilienkamp, Henning A1 - von Specht, Sebastian A1 - Weatherill, Graeme A1 - Caire, Giuseppe A1 - Cotton, Fabrice T1 - Ground-Motion modeling as an image processing task BT - introducing a neural network based, fully data-driven, and nonergodic JF - Bulletin of the Seismological Society of America N2 - We construct and examine the prototype of a deep learning-based ground-motion model (GMM) that is both fully data driven and nonergodic. We formulate ground-motion modeling as an image processing task, in which a specific type of neural network, the U-Net, relates continuous, horizontal maps of earthquake predictive parameters to sparse observations of a ground-motion intensity measure (IM). The processing of map-shaped data allows the natural incorporation of absolute earthquake source and observation site coordinates, and is, therefore, well suited to include site-, source-, and path-specific amplification effects in a nonergodic GMM. Data-driven interpolation of the IM between observation points is an inherent feature of the U-Net and requires no a priori assumptions. We evaluate our model using both a synthetic dataset and a subset of observations from the KiK-net strong motion network in the Kanto basin in Japan. We find that the U-Net model is capable of learning the magnitude???distance scaling, as well as site-, source-, and path-specific amplification effects from a strong motion dataset. The interpolation scheme is evaluated using a fivefold cross validation and is found to provide on average unbiased predictions. The magnitude???distance scaling as well as the site amplification of response spectral acceleration at a period of 1 s obtained for the Kanto basin are comparable to previous regional studies. Y1 - 2022 U6 - https://doi.org/10.1785/0120220008 SN - 0037-1106 SN - 1943-3573 VL - 112 IS - 3 SP - 1565 EP - 1582 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - Pilz, Marco A1 - Cotton, Fabrice Pierre A1 - Razafindrakoto, Hoby Njara Tendrisoa A1 - Weatherill, Graeme A1 - Spies, Thomas T1 - Regional broad-band ground-shaking modelling over extended and thick sedimentary basins BT - An example from the Lower Rhine Embayment (Germany) JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - The simulation of broad-band (0.1 to 10 + Hz) ground-shaking over deep and spatially extended sedimentary basins at regional scales is challenging. We evaluate the ground-shaking of a potential M 6.5 earthquake in the southern Lower Rhine Embayment, one of the most important areas of earthquake recurrence north of the Alps, close to the city of Cologne in Germany. In a first step, information from geological investigations, seismic experiments and boreholes is combined for deriving a harmonized 3D velocity and attenuation model of the sedimentary layers. Three alternative approaches are then applied and compared to evaluate the impact of the sedimentary cover on ground-motion amplification. The first approach builds on existing response spectra ground-motion models whose amplification factors empirically take into account the influence of the sedimentary layers through a standard parameterization. In the second approach, site-specific 1D amplification functions are computed from the 3D basin model. Using a random vibration theory approach, we adjust the empirical response spectra predicted for soft rock conditions by local site amplification factors: amplifications and associated ground-motions are predicted both in the Fourier and in the response spectra domain. In the third approach, hybrid physics-based ground-motion simulations are used to predict time histories for soft rock conditions which are subsequently modified using the 1D site-specific amplification functions computed in method 2. For large distances and at short periods, the differences between the three approaches become less notable due to the significant attenuation of the sedimentary layers. At intermediate and long periods, generic empirical ground-motion models provide lower levels of amplification from sedimentary soils compared to methods taking into account site-specific 1D amplification functions. In the near-source region, hybrid physics-based ground-motions models illustrate the potentially large variability of ground-motion due to finite source effects. KW - ground-motion modelling KW - site effects KW - scenario KW - random vibration KW - theory KW - hybrid modelling Y1 - 2020 U6 - https://doi.org/10.1007/s10518-020-01004-w SN - 1570-761X SN - 1573-1456 VL - 19 IS - 2 SP - 581 EP - 603 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Bindi, Dino A1 - Kotha, Sreeram Reddy A1 - Weatherill, Graeme A1 - Lanzano, Giovanni A1 - Luzi, Lucia A1 - Cotton, Fabrice Pierre T1 - The pan-European engineering strong motion (ESM) flatfile BT - consistency check via residual analysis JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - We present the results of a consistency check performed over the flatfile extracted from the engineering strong motion (ESM) database. The flatfile includes 23,014 recordings from 2179 earthquakes in the magnitude range from 3.5 to 7.8 that occurred since the 1970s in Europe and Middle East, as presented in the companion article by Lanzano et al. (Bull Earthq Eng, 2018a). The consistency check is developed by analyzing different residual distributions obtained from ad-hoc ground motion prediction equations for the absolute spectral acceleration (SA), displacement and Fourier amplitude spectra (FAS). Only recordings from earthquakes shallower than 40 km are considered in the analysis. The between-event, between-station and event-and-station corrected residuals are computed by applying a mixed-effect regression. We identified those earthquakes, stations, and recordings showing the largest deviations from the GMPE median predictions, and also evaluated the statistical uncertainty on the median model to get insights on the applicable magnitude–distance ranges and the usable period (or frequency) range. We observed that robust median predictions are obtained up to 8 s for SA and up to 20 Hz for FAS, although median predictions for Mw ≥ 7 show significantly larger uncertainties with ‘bumps’ starting above 5 s for SA and below 0.3 Hz for FAS. The between-station variance dominates over the other residual variances, and the dependence of the between-station residuals on logarithm of Vs30 is well-described by a piece-wise linear function with period-dependent slopes and hinge velocity around 580 m/s. Finally, we compared the between-event residuals obtained by considering two different sources of moment magnitude. The results show that, at long periods, the between-event terms from the two regressions have a weak correlation and the overall between-event variability is dissimilar, highlighting the importance of magnitude source in the regression results. KW - Ground motion prediction equation KW - Residual analysis KW - European strong motion data Y1 - 2018 U6 - https://doi.org/10.1007/s10518-018-0466-x SN - 1570-761X SN - 1573-1456 VL - 17 IS - 2 SP - 583 EP - 602 PB - Springer CY - Dordrecht ER -