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Susceptibility of microseismic triggering to small sinusoidal stress perturbations at the laboratory scale / Martin Colledge in Journal of geophysical research : Solid Earth, vol 128 n° 4 (April 2023)  

Public [article]  inJournal of geophysical research : Solid Earth > vol 128 n° 4 (April 2023) . - n° e2022JB025583 Titre : Susceptibility of microseismic triggering to small sinusoidal stress perturbations at the laboratory scale Type de document : Article/Communication Auteurs : Martin Colledge, Auteur ; Jérôme Aubry, Auteur ; Kristel Chanard , Auteur ; François Pétrélis, Auteur ; Clara Duverger, Auteur ; Laurent Bollinger, Auteur ; Alexandre Schubnel, Auteur Année de publication : 2023 Article en page(s) : n° e2022JB025583 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] onde sismique [Termes IGN] oscillation [Termes IGN] risque naturel [Termes IGN] séisme [Termes IGN] sismicité Résumé : (auteur) Small transient stress perturbations are prone to trigger (micro)seismicity. In the Earth's crust, these stress perturbations can be caused by various sources such as the passage of seismic waves, forcing by tides, or hydrological seasonal loads. A better understanding of the dynamic of earthquake triggering by stress perturbations is essential to improve our understanding of earthquake physics and our consideration of seismic hazard. Here, we study an experimental sandstone-gouge-filled fault system undergoing combined far field loading and periodic stress perturbations (of variable amplitude and frequency) at crustal pressure conditions. Microseismicity—in the form of acoustic emissions (AEs)—strains, and stresses, are continuously recorded in order to study the response of microseismicity as a function of loading rate, amplitude, and frequency of a periodic stress perturbation. The observed AE distributions do not follow the predictions of either a Coulomb failure model, taking into account both constant loading and oscillation-induced strain rates, or a rate and state model. A susceptibility of the system's AE response to the amplitude of the confinement pressure perturbation is estimated, which highlights a linear relation between confinement pressure amplitude and the AE response amplitude, observations which agree with recent higher frequency experimental results on dynamic triggering. The magnitude-frequency distribution of AEs is also computed. The Gutenberg-Richter b-value oscillates with stress oscillations. Our experiments may help complement our understanding of the influence of low inertia stress phenomena on the distribution of seismicity, such as observations of dynamic triggering and seismicity modulation by tides or hydrological loading. Numéro de notice : A2023-095 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2022JB025583 Date de publication en ligne : 13/04/2023 En ligne : https://doi.org/10.1029/2022JB025583 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103211 [article]

Characterization of mass variations in Antarctica in response to climatic fluctuations from space-based gravimetry and radar altimetry data / Athul Kaitheri (2021)  

Public Titre : Characterization of mass variations in Antarctica in response to climatic fluctuations from space-based gravimetry and radar altimetry data Titre original : Caractérisation des variations de masse en Antarctique en réponse aux fluctuations climatiques à partir des données de gravimétrie spatiale et d’altimétrie radar Type de document : Thèse/HDR Auteurs : Athul Kaitheri, Auteur ; Anthony Mémin, Directeur de thèse ; Frédérique Rémy, Directeur de thèse Editeur : Nice : Université Côte d'Azur Année de publication : 2021 Importance : 138 p. Format : 21 x 30 cm Note générale : Bibliographie Thèse présentée en vue de l’obtention du grade de docteur de l'Université de Côte d'Azur, Spécialité Sciences de la Planète et de l'Univers Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] altimétrie satellitaire par radar [Termes IGN] analyse comparative [Termes IGN] Antarctique [Termes IGN] calotte glaciaire [Termes IGN] changement climatique [Termes IGN] données altimétriques [Termes IGN] données GRACE [Termes IGN] image Envisat [Termes IGN] levé gravimétrique [Termes IGN] masse [Termes IGN] oscillation [Termes IGN] régression Index. décimale : THESE Thèses et HDR Résumé : (Auteur) Quantifying the mass balance of the Antarctic Ice Sheet (AIS), and the resulting sea level rise, requires an understanding of inter-annual variability and associated causal mechanisms. This has become more complex and challenging in the backdrop of global climate change. Very few studies have been exploring the influence of climate anomalies on the AIS and only a vague estimate of its impact is available. Usually changes to the ice sheet are quantified using observations from space-borne altimetry and gravimetry missions. In this study, we use data from Envisat (2002 to 2010) and Gravity Recovery and Climate Experiment (GRACE) (2002 to 2016) missions to estimate monthly elevation changes and mass changes, respectively. Similar estimates of the changes are made using weather variables (surface mass balance (SMB) and temperature) from a regional climate model (RACMO2.3p2) as inputs to a firn compaction (FC) model. Using the firn compaction model we were able to model the transformation of snow into glacial ice and hence estimate changes in the elevation of the ice sheet using climate parameters. Elevation changes estimated from different techniques are in good agreement with each other across the AIS especially in West Antarctica, Antarctic Peninsula, and along the coasts of East Antarctica. Inter-annual height change patterns are then extracted using for the first time an empirical mode decomposition followed by a reconstruction of modes. These signal on applying least square method revealed a sub-4-year periodic signal in the all the three distinct height change patterns. This was indicative of the influence of the El Niño Southern Oscillation (ENSO), a climate anomaly that alters, among other parameters, moisture transport, sea surface temperature, precipitation, in and around the AIS at similar frequency by alternating between warm and cold conditions. But there existed altering periodic behavior among inter annual height change patterns in the Antarctic Pacific (AP) sector which was found possibly by the influence of multiple climate drivers, like the Amundsen Sea Low (ASL) and the Southern Annular Mode (SAM). A combined analysis of the three distinct estimates using a PCA (principal component analysis) along the coast revealed similar findings. Height change anomaly also appears to traverse eastwards from Coats Land to Pine Island Glacier (PIG) regions passing through Dronning Maud Land (DML) and Wilkes Land (WL) in 6 to 8 years. This is indicative of climate anomaly traversal due to the Antarctic Circumpolar Wave (ACW) which propagates anomalies through the Southern Ocean in 8 to 10 years. Altogether, inter-annual variability in the SMB of the AIS is found to be modulated by multiple competing climate anomalies. Note de contenu : 1. Introduction 1.1 Climate change scenario 1.2 Antarctica 1.3 Thesis overview 2. Height changes from satellite observations 2.1 Observations 2.2 Satellite gravimetry 2.3 Satellite altimetry 3. Height changes from modelling 3.1 Climate Model 3.2 Height changes from RACMO2.3p2 outputs 3.3 Firn densification model 4. Inter-annual variability 4.1 Comparison between height changes 4.2 Extraction of inter annual signals 4.3 Characterizing inter-annual signals 4.4 Principal component analysis 5. Influence of climate anomalies 5.1 El Ni˜no Southern Oscillation 5.2 Southern Annular Mode 5.3 Amundsen Sea Low 5.4 Antarctic Circumpolar Wave 6. General conclusions 6.1 Conclusions 6.2 Future perspectives Numéro de notice : 26825 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de doctorat : Sciences de la Planète et de l'Univers : Côte d'Azur : 2021 Organisme de stage : Géoazur nature-HAL : Thèse DOI : sans Date de publication en ligne : 19/04/2022 En ligne : https://tel.hal.science/tel-03644306/ Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100655

Estimation of frequency and duration of ionospheric disturbances over Turkey with IONOLAB-FFT algorithm / Secil Karatay in Journal of geodesy, vol 94 n° 9 (September 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 9 (September 2020) . - n° 89 Titre : Estimation of frequency and duration of ionospheric disturbances over Turkey with IONOLAB-FFT algorithm Type de document : Article/Communication Auteurs : Secil Karatay, Auteur Année de publication : 2020 Article en page(s) : n° 89 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] fréquence [Termes IGN] oscillation [Termes IGN] perturbation ionosphérique [Termes IGN] récepteur bifréquence [Termes IGN] récepteur GPS [Termes IGN] teneur totale en électrons [Termes IGN] transformation rapide de Fourier [Termes IGN] Turquie Résumé : (auteur) One of the more common methods of observation of variability of the Earth’s ionosphere is based on total electron content (TEC) estimated from ground-based dual-frequency Global Positioning System (GPS) receivers. Variations in solar, geomagnetic and seismic activity cause depletions or enhancements in the ionospheric electron concentrations that can be detected as disturbances. Some of these disturbances have wave-like characteristics, where frequency of oscillation can be used to identify and classify the disturbance. In this study, the frequency of such periodic disturbances is estimated using a fast Fourier transform (FFT)-based method, namely IONOLAB-FFT, in the spectral domain. IONOLAB-FFT, which was initially developed to be used on slant TEC (STEC), is modified to be applied to TEC in the local zenith direction of the receiver. The algorithm is tested using literature data on disturbances generated by a geomagnetic activity, a solar flare, a medium-scale traveling ionospheric disturbance (MSTID), a large-scale TID (LSTID) and an earthquake. An accordance with these known disturbances is observed in running IONOLAB-FFT, and the main frequencies and durations of the disturbances are estimated. IONOLAB-FFT method is applied to TEC computed from Turkish Permanent GPS Network (TNPGN-Active) which lies in mid-latitude region to detect the any wave-like oscillations, sudden disturbances and other irregularities during December, March, June and September months for 2010, 2011 and 2012 years. It is observed that a large number of the estimated frequencies are accumulated between 0.08 and 0.14 MHz corresponding to periods of 3.5 h to 2 h. The significant frequencies are grouped less than 0.28 MHz. A large number of the durations of the oscillations are between 425 and 550 min in 2010, 300 and 550 min in 2011 and 350 and 400 min in 2012. The longest duration (around 800 min: 13.33 h) is observed in December months, and the shortest duration (around 2 h) is observed in September months. Numéro de notice : A2020-541 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01416-1 Date de publication en ligne : 31/08/2020 En ligne : https://doi.org/10.1007/s00190-020-01416-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95743 [article]

Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations / Li Zhang in Journal of applied geodesy, vol 14 n° 2 (April 2020)  

Public [article]  inJournal of applied geodesy > vol 14 n° 2 (April 2020) . - pp 167 – 175 Titre : Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations Type de document : Article/Communication Auteurs : Li Zhang, Auteur ; Volker Schwieger, Auteur Année de publication : 2020 Article en page(s) : pp 167 – 175 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] atténuation du signal [Termes IGN] corrélation temporelle [Termes IGN] coût [Termes IGN] itération [Termes IGN] ligne de base [Termes IGN] oscillation [Termes IGN] phase [Termes IGN] plan de masse [Termes IGN] qualité des données [Termes IGN] récepteur GNSS [Termes IGN] récepteur monofréquence [Termes IGN] réflecteur [Termes IGN] source d'erreur [Termes IGN] trajet multiple Résumé : (auteur) The investigations on low-cost single frequency GNSS receivers at the Institute of Engineering Geodesy (IIGS) show that u-blox GNSS receivers combined with low-cost antennas and self-constructed L1-optimized choke rings can reach an accuracy which almost meets the requirements of geodetic applications (see Zhang and Schwieger [25]). However, the quality (accuracy and reliability) of low-cost GNSS receiver data should still be improved, particularly in environments with obstructions. The multipath effects are a major error source for the short baselines. The ground plate or the choke ring ground plane can reduce the multipath signals from the horizontal reflector (e. g. ground). However, the shieldings cannot reduce the multipath signals from the vertical reflectors (e. g. walls). Because multipath effects are spatially and temporally correlated, an algorithm is developed for reducing the multipath effect by considering the spatial correlations of the adjoined stations (see Zhang and Schwieger [24]). In this paper, an algorithm based on the temporal correlations will be introduced. The developed algorithm is based on the periodic behavior of the estimated coordinates and not on carrier phase raw data, which is easy to use. Because, for the users, coordinates are more accessible than the raw data. The multipath effect can cause periodic oscillations but the periods change over time. Besides this, the multipath effect’s influence on the coordinates is a mixture of different multipath signals from different satellites and different reflectors. These two properties will be used to reduce the multipath effect. The algorithm runs in two steps and iteratively. Test measurements were carried out in a multipath intensive environment; the accuracies of the measurements are improved by about 50 % and the results can be delivered in near-real-time (in ca. 30 minutes), therefore the algorithm is suitable for structural health monitoring applications. Numéro de notice : A2020-217 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0059 Date de publication en ligne : 27/03/2020 En ligne : https://doi.org/10.1515/jag-2019-0059 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94910 [article]

Cyclic asymptotic behaviour of a population reproducing by fission into two equal parts / Etienne Bernard in Kinetic & Related Models, vol 12 n° 3 (June 2019)  

Public [article]  inKinetic & Related Models > vol 12 n° 3 (June 2019) . - pp 551 - 571 Titre : Cyclic asymptotic behaviour of a population reproducing by fission into two equal parts Type de document : Article/Communication Auteurs : Etienne Bernard , Auteur ; Marie Doumic, Auteur ; Pierre Gabriel, Auteur Année de publication : 2019 Projets : KIBORD / Article en page(s) : pp 551 - 571 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] asymptote [Termes IGN] comportement [Termes IGN] entropie [Termes IGN] oscillation Résumé : (auteur) We study the asymptotic behaviour of the following linear growth-fragmentation equation xxxxxxx and prove that under fairly general assumptions on the division rate B(x),its solution converges towards an oscillatory function, explicitely given by the projection of the initial state on the space generated by the countable set of the dominant eigenvectors of the operator. Despite the lack of hypo-coercivity of the operator, the proof relies on a general relative entropy argument in a convenient weighted L2 space, where well-posedness is obtained via semigroup analysis. We also propose a non-dissipative numerical scheme, able to capture the oscillations. Numéro de notice : A2019-158 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3934/krm.2019022 En ligne : http://dx.doi.org/10.3934/krm.2019022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93294 [article]

Voir aussi

• Cyclic asymptotic behaviour of a population reproducing by fission into two equal parts / Etienne Bernard (2017)    

The possibility of measuring the dynamic response of structures using non-contact geodetic method / Bostjan Kovacic in Geodetski vestnik, vol 63 n° 1 (March - May 2019)  

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Physics of oscillations and waves / Arnt Inge Vistnes (2018)  

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Analysing normal modes of the Earth from high-rate GNSS time series / Zhongyi Chen (2017)  

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Ultra short-term prediction of pole coordinates via combination of empirical mode decomposition and neural networks / Yu Lei in Artificial satellites, vol 51 n° 4 (December 2016)  

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Impact of the North Atlantic oscillation on Southern Europe water distribution: insights from geodetic data / Pierre Valty in Earth Interactions, vol 19 n° 10 (September 2015)    

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GPS time-variable seasonal signals modeling / Qiang Chen (2015)  

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Les effets de l'oscillation Nord-Atlantique sur les transferts de masse, vus par géodésie / Pierre Valty in XYZ, n° 139 (juin - août 2014) 

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Hydrological deformation induced by the West African Monsoon : Comparison of GPS, GRACE and loading models / Samuel Nahmani in Journal of geophysical research : Solid Earth, Vol 117 n° B5 (May 2012)  

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Pacific geoid anomalies revisited in light of thermochemical oscillating domes in the lower mantle / Cécilia Cadio in Earth and planetary science letters, vol 306 n° 1-2 (June 2011)  

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TIDES, a new descriptor for time series oscillation behavior / L. Mariote in Geoinformatica, vol 15 n° 1 (January 2011)  

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