Fabrice Cotton

Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ | GFZ · Division of Seismic Hazards and Stress Field

Short term prediction of earthquake magnitude, time, and location is currently not possible. In some cases, however, documented observations have been retrospectively considered as precursory. Here we present seismicity transients starting approx. 8 months before the 2023 MW 7.8 Kahramanmaraş earthquake on the East Anatolian Fault Zone. Seismicity...

Cite this article as We investigate the source scaling and ground-motion variability of 1585 earthquakes with M w > 3 occurring along the East Anatolian fault since 2010. We compile a dataset of 17,691 Fourier amplitude spectra of S waves recorded by 186 stations. A spectral decomposition is applied to isolate the source contribution from propagati...

The latest generation of national and regional probabilistic seismic hazard assessments (PSHA) in Europe presents stakeholders with multiple representations of the hazard in many regions. This raises the question of why and by how much seismic hazard estimates between two or more models differ, not where models overlap geographically but also where...

Despite significant advancements in predictive modeling, the death toll and monetary damages caused by landslides continue to escalate. A critical limitation in enhancing the predictive capability of these models is the 'incomplete' nature of landslide databases. Specifically, these databases often lack essential details such as the types of landsl...

Public earthquake early warning systems (PEEWSs) have the potential to save lives by warning people of incoming seismic waves up to tens of seconds in advance. Given the scale and geographical extent of their impact, this potential is greatest for destructive earthquakes, such as the M7.8 Pazarcik (Türkiye) event of 6 February 2023, which killed al...

The 1400 km long North Anatolian Fault Zone in Türkiye runs through numerous densely populated regions, including the city of Düzce that was recently hit by an Mw 6.1 earthquake on 23 November 2022. This was the first moderate event in the region after the devastating Mw 7.2 earthquake in 1999, which cost the lives of over 700 people. Despite its m...

Current practice in strong ground motion modelling for probabilistic seismic hazard analysis (PSHA) requires the identification and calibration of empirical models appropriate to the tectonic regimes within the region of application, along with quantification of both their aleatory and epistemic uncertainties. For the development of the 2020 Europe...

Site-specific seismic hazard studies require the knowledge of the shear-wave velocity VS and the high-frequency site attenuation parameter κ0 at the reference rock level at depth. The latter one (called κ0,ref) is often not available and hard to derive. In this study, we make use of the KiK-net database in Japan that consists of surface and colocat...

To test whether a globally inferred sediment thickness value from geomorphological studies can be used as a proxy to predict earthquake site amplification, we derive site amplification models from the relation between empirical amplification for sites in Europe and Turkey, and the geomorphological sediment thickness. The new site amplification pred...

Probabilistic seismic hazard estimates are a key ingredient of earthquake risk mitigation strategies and are often communicated through seismic hazard maps. Though the literature suggests that visual design properties are key for effective communication using such maps, guidelines on how to optimally design hazard maps are missing from the literatu...

To design user-centred and scientifically high-quality outreach products to inform about earthquake-related hazards and the associated risk, a close collaboration between the model developers and communication experts is needed. In this contribution, we present the communication strategy developed to support the public release of the first openly a...

In this paper, we explore the use of seismicity data on a single-station basis in site response characterization. We train a supervised deep-learning model, SeismAmp, to recognize and separate seismic site response with reference to seismological bedrock (VS=3.45 km/s) in a broad frequency range (0.2–20 Hz) directly from single-station earthquake r...

We present the status of ShakeMap-EU, an initiative initially proposed in 2018 to: (i) provide an integrated archive of ShakeMaps at the European level built on EPOS Seismology (www.epos-eu.org/tcs/seismology) services & data products and modern community software; (ii) serve as a backup to authoritative ShakeMap implementations; (iii) deliver Shak...

Timely manner seismic data processing and analyses are essential for potential eruption prediction and early warning in volcanology. However, the complexity of eruption processes and precursory activities makes the analysis challenging. Here, we show that advanced machine learning techniques can provide an effective and efficient tool for extractin...

The understanding of coupled thermo-hydro-mechanical behaviour of fault zones or in naturally fractured reservoirs is essential both for fundamental and applied sciences and in particular for the safety assessment of radioactive waste disposal facilities. The overall objective of the CHENILLE project is to better understand the physical processes r...

Short term prediction of the magnitude, time, and location of earthquakes is currently not possible. In some cases, however, behaviour has been documented that has been retrospectively considered as precursory. Some models hold that on a timescale of several years, increasing levels of background seismic activity may signify enhanced damage generat...

Rapid assessment of an earthquake's impact on the affected society is a crucial step in the early phase of disaster management, navigating the need for further emergency response measures. We demonstrate that felt reports collected via the LastQuake service of the European Mediterranean Seismological Center can be utilized to rapidly estimate the p...

Earthquake early warning (EEW) systems can serve as a viable solution to protect specific hazard‐prone targets (major cities or critical infrastructure) against harmful seismic events. Using the example of the Lower Rhine Embayment (western Germany), we present a novel approach for evaluating and optimizing seismic networks for EEW purposes. The ne...

In this paper, we train a supervised deep-learning model, SeismAmp, to recognize and separate seismic site response with reference to seismological bedrock in a broad frequency range (0.2-~20 Hz) from single-station three-component seismograms (features). Ground-truth data are homogeneously created using a classical multi-station approach-generaliz...

A key component in seismic hazard assessment is the determination of time histories for hard-rock site conditions, either as input motion for site response computations or for applications to installations built on this site type. The state of the practice is to apply physics-based corrections for removing site effects from surface recordings to ob...

Despite the exponential growth of the amount of ground‐motion data, ground‐motion records are not always available for all distances, magnitudes, and site conditions cases. Given the importance of using time histories for earthquake engineering (e.g., nonlinear dynamic analysis), simulations of time histories are therefore required. In this study,...

Quantitative estimation of seismic risk over a region requires both an underlying probabilistic seismic hazard model and a means to characterise shallow site response over a large scale. The 2020 European Seismic Risk Model (ESRM20) builds on the 2020 European Seismic Hazard Model (ESHM20), requiring additional information to firstly parameterise t...

Superficial geological layers can strongly modify the surface ground motion induced by an earthquake. These so-called site effects are highly variable from one site to another and still difficult to quantify for complex geological configurations. That is why site-specific studies can greatly contribute to improve the hazard prediction at a specific...

Probabilistic seismic hazard estimates are a key ingredient of earthquake risk mitigation strategies and are often communicated through seismic hazard maps. Though the literature suggests that visual design properties are key for effective communication using such maps, guidelines on how to optimally design hazard map are missing from the literatur...

We process a large number of seismic recordings in Europe (i.e. about half a million recordings from about 19 500 earthquakes) with the aim of decomposing the Fourier amplitude spectra into source, propagation and site effects. To account for first-order, large-scale regional differences in propagation effects, the spectral decomposition simultaneo...

This is a summary of two of our previous studies (Zhu et al., 2022a, b). In site response assessments, observation-based site-specific approaches requiring a target-reference recording pair or a recording network cannot be implemented at many sites of interest. Thus, various estimation techniques have to be utilized. How effective are these techniq...

The 2020 update of the European Seismic Hazard Model (ESHM20) is the most recent seismic hazard model of the Euro-Mediterranean region. It was built upon unified and homogenized datasets including earthquake catalogues, active faults, ground motion recordings and state-of-the-art modelling components, i.e. earthquake rates forecast and regionally v...

In site-specific site response assessments, observation-based site-specific approaches requiring a target-reference recording pair or a regional recording network cannot be implemented at many sites of interest. Thus, various estimation techniques have to be utilized. How effective are these techniques in predicting site-specific site responses (av...

Multi-hazard risk assessments for building portfolios exposed to earthquake shaking followed by a tsunami are usually based on empirical vulnerability models calibrated on post-event surveys of damaged buildings. The applicability of these models cannot easily be extrapolated to other regions of larger/smaller events. Moreover, the quantitative eva...

Strong ground motion can generate a large dynamic strain in shallow materials, lead to a nonlinear response, and cause permanent damage in near-surface materials. The nonlinear behavior of soils subjected to strong vibrations leads to an increase in wave attenuation and a decrease in shear modulus. These effects lead to a decrease in the resonance...

Plain Language Summary Large earthquakes modify the state of stress and pore pressure in the upper crust and mantle. These changes induce stress relaxation processes and pore pressure diffusion in the postseismic phase. The two main stress relaxation processes are postseismic slip along the rupture plane of the earthquake and viscoelastic deformati...

In this article we describe EPOS Seismology, the Thematic Core Service consortium for the seismology domain within the European Plate Observing System infrastructure. EPOS Seismology was developed alongside the build-up of EPOS during the last decade, in close collaboration between the existing pan-European seismological initiatives ORFEUS (Observa...

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 observation...

In seismic risk assessment, the sources of uncertainty associated with building exposure modelling have not received as much attention as other components related to hazard and vulnerability. Conventional practices such as assuming absolute portfolio compositions (i.e., proportions per building class) from expert-based assumptions over aggregated d...

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)....

Ground-motion models (GMMs) are often used to predict the random distribution of Spectral accelerations (SAs) at a site due to a nearby earthquake. In probabilistic seismic hazard and risk assessment, large earthquakes occurring close to a site are considered as critical scenarios. GMMs are expected to predict realistic SAs with low within-model un...

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...

Earthquake site responses or site effects are the modifications of surface geology to seismic waves. How well can we predict the site effects (average over many earthquakes) at individual sites so far? To address this question, we tested and compared the effectiveness of different estimation techniques in predicting the outcrop Fourier site respons...

Typical seismic ground-motion models predict the response spectral ordinates (GMM-SA), which are the damped responses of a suite of single-degree-of-freedom oscillators. Response spectra represent the response of an idealized structure to input ground-motion, but not the physics of the actual ground-motion. To complement the regionally adaptable GM...

Fault zones are major sources of hazard for many populated regions around the world. Earthquakes still occur unanticipated, and research has started to observe fault properties with increasing spatial and temporal resolution, having the goal of detecting signs of stress accumulation and strength weakening that may anticipate the rupture. The common...

The within-site variability in site response is the randomness in site response at a given site from different earthquakes and is treated as aleatory variability in current seismic hazard/risk analyses. In this study, we investigate the single-station variability in linear site response at K-NET and KiK-net stations in Japan using a large number of...

We propose the use of variable resolution boundaries based on central Voronoi tessellations (CVTs) to spatially aggregate building exposure models for risk assessment to various natural hazards. Such a framework is especially beneficial when the spatial distribution of the considered hazards presents intensity measures with contrasting footprints a...

One-dimensional (1D) site response analysis dominates earthquake engineering practice, while local 2D/3D models are often required at sites where the site response is complex. For such sites, the 1D representation of the soil column can account neither for topographic effects or dipping layers nor for locally generated horizontally propagating surf...

In site response assessments, observation-based site-specific approaches requiring a target-reference recording pair or a recording network cannot be implemented at many sites of interest. Thus, various estimation techniques have to be utilized. How effective are these techniques in predicting site-specific site responses (average over many earthqu...

Far away landslide detection A mass wasting and flood event on 7 February 2021 in Uttarakhand, India, killed more than 200 people and damaged two hydropower plants. Cook et al . discovered that teleseimic signals from the beginning of this event were recorded at different stations on a regional seismic network in northern India. The signals were ob...

Ground motion with strong-velocity pulses can cause significant damage to buildings and structures at certain periods; hence, knowing the period and velocity amplitude of such pulses is critical for earthquake structural engineering. However, the physical factors relating the scaling of pulse periods with magnitude are poorly understood. In this st...