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The 2018–2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption / Anne Lemoine in Geophysical journal international, vol 223 n° 1 (October 2020)  

Public [article]  inGeophysical journal international > vol 223 n° 1 (October 2020) . - pp 22 - 44 Titre : The 2018–2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption Type de document : Article/Communication Auteurs : Anne Lemoine, Auteur ; Pierre Briole, Auteur ; Didier Bertil, Auteur ; Agathe Roullé, Auteur ; Michael Foumelis, Auteur ; Isabelle Thinon, Auteur ; Daniel Raucoules, Auteur ; Marcello de Michele, Auteur ; Pierre Valty , Auteur ; Roser Hoste Colomer, Auteur Année de publication : 2020 Article en page(s) : pp 22 - 44 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Comores (îles) [Termes IGN] coordonnées GPS [Termes IGN] éruption volcanique [Termes IGN] fond marin [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] Mayotte [Termes IGN] séisme Résumé : (auteur) On 10 May 2018, an unprecedented long and intense seismic crisis started offshore, east of Mayotte, the easternmost of the Comoros volcanic islands. The population felt hundreds of events. Over the course of 1 yr, 32 earthquakes with magnitude greater than 5 occurred, including the largest event ever recorded in the Comoros (Mw = 5.9 on 15 May 2018). Earthquakes are clustered in space and time. Unusual intense long lasting monochromatic very long period events were also registered. From early July 2018, Global Navigation Satellite System (GNSS) stations and Interferometric Synthetic Aperture Radar (InSAR) registered a large drift, testimony of a large offshore deflation. We describe the onset and the evolution of a large magmatic event thanks to the analysis of the seismicity from the initiation of the crisis through its first year, compared to the ground deformation observation (GNSS and InSAR) and modelling. We discriminate and characterize the initial fracturing phase, the phase of magma intrusion and dyke propagation from depth to the subsurface, and the eruptive phase that starts on 3 July 2018, around 50 d after the first seismic events. The eruption is not terminated 2 yr after its initiation, with the persistence of an unusual seismicity, whose pattern has been similar since summer 2018, including episodic very low frequency events presenting a harmonic oscillation with a period of ∼16 s. From July 2018, the whole Mayotte Island drifted eastward and downward at a slightly increasing rate until reaching a peak in late 2018. At the apex, the mean deformation rate was 224 mm yr−1 eastward and 186 mm yr−1 downward. During 2019, the deformation smoothly decreased and in January 2020, it was less than 20 per cent of its peak value. A deflation model of a magma reservoir buried in a homogenous half space fits well the data. The modelled reservoir is located 45 ± 5 km east of Mayotte, at a depth of 28 ± 3 km and the inferred magma extraction at the apex was ∼94 m3 s−1. The introduction of a small secondary source located beneath Mayotte Island at the same depth as the main one improves the fit by 20 per cent. While the rate of the main source drops by a factor of 5 during 2019, the rate of the secondary source remains stable. This might be a clue of the occurrence of relaxation at depth that may continue for some time after the end of the eruption. According to our model, the total volume extracted from the deep reservoir was ∼2.65 km3 in January 2020. This is the largest offshore volcanic event ever quantitatively documented. This seismo-volcanic crisis is consistent with the trans-tensional regime along Comoros archipelago. Numéro de notice : A2020-842 Affiliation des auteurs : IGN+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggaa273 Date de publication en ligne : 03/06/2020 En ligne : https://doi.org/10.1093/gji/ggaa273 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98513 [article]

Velocity field and crustal deformation of broader Athens plain (Greece) from a dense geodetic network / Michael Foumelis in Journal of applied geodesy, Vol 13 n° 4 (October 2019)  

Public [article]  inJournal of applied geodesy > Vol 13 n° 4 (October 2019) . - pp 305 – 316 Titre : Velocity field and crustal deformation of broader Athens plain (Greece) from a dense geodetic network Type de document : Article/Communication Auteurs : Michael Foumelis, Auteur Année de publication : 2019 Article en page(s) : pp 305 – 316 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Athènes [Termes IGN] calcul tensoriel [Termes IGN] champ de vitesse [Termes IGN] déformation de la croute terrestre [Termes IGN] extensométrie [Termes IGN] géodynamique [Termes IGN] positionnement par GNSS [Termes IGN] réseau géodésique dense [Termes IGN] tectonique Résumé : (auteur) The broader area of Athens, a region exhibiting relatively low crustal deformation, was stroke in 1999 by a catastrophic earthquake posing serious questions regarding strain accumulation in slow deforming regions located within active geodynamic regimes. In the present study, the establishment of a dense geodetic network, primarily designed to monitor local tectonic movements is reported. A comprehensive GNSS velocity field, over the period 2005–2008, as well as calculated geodetic strain rates is presented. It is shown that a single strain tensor is insufficient to express the heterogeneity of the local geodetic field. Local variability of strain is successfully depicted, indicating the western part of Athens as the area of higher strain accumulation. Maximum dilatation rates occur along a NNE-SSW direction between Parnitha Mt. and Thriasio basin. The observed dilatation can be associated to WNW-ESE trending active fault zones, which appear to abruptly terminate towards East along a major NNE-SSW Miocene tectonic boundary. These findings are consistent to the stress field responsible for the Athens 1999 earthquake, also in agreement with geological and tectonic observations. Finally, the implications of the observed motion field on the understanding of the kinematics and dynamics of the region as well as the role of inherited inactive tectonic structures are discussed. Numéro de notice : A2019-541 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0012 Date de publication en ligne : 04/07/2019 En ligne : https://doi.org/10.1515/jag-2019-0012 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94180 [article]

Vector-based approach for combining ascending and descending persistent scatterers interferometric point measurements / Michael Foumelis in Geocarto international, vol 33 n° 1 (January 2018)  

Public [article]  inGeocarto international > vol 33 n° 1 (January 2018) . - pp 38 - 52 Titre : Vector-based approach for combining ascending and descending persistent scatterers interferometric point measurements Type de document : Article/Communication Auteurs : Michael Foumelis, Auteur Année de publication : 2018 Article en page(s) : pp 38 - 52 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] classification barycentrique [Termes IGN] géodatabase [Termes IGN] interferométrie différentielle [Termes IGN] interpolation spatiale [Termes IGN] modèle numérique de terrain [Termes IGN] système d'information géographique [Termes IGN] volcan Résumé : (Auteur) The combination of ascending and descending persistent scatterers interferometric (PSI) data by means of resampling and/or spatial interpolation, separately for each synthetic aperture radar geometry, is a commonly followed procedure, limited though by the reduced spatial coverage and the introduced uncertainties from multiple rasterization steps. Herein, an alternative approach is proposed for combining different PSI line-of-sight observables in the vector domain, based on the geographic proximity of PS point targets. In the proposed nearest neighbour vector approach all necessary analysis steps are performed by means of attributes transfer and calculations between features geodatabases, prior to any rasterization. By increasing the number of input point vectors during subsequent interpolation, the overall error budget coming from spatial interpolation is being reduced. The advantages of the proposed vector-based approach compared to the commonly used grid-based procedure are being demonstrated using real data. Numéro de notice : A2018-031 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106049.2016.1222636 En ligne : https://doi.org/10.1080/10106049.2016.1222636 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89200 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
059-2018011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

On the SAR backscatter of burned forests: a model-based study in C-Band, over burned pine canopies full text / Vasileios kalogirou in IEEE Transactions on geoscience and remote sensing, vol 52 n° 10 tome 1 (October 2014)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 52 n° 10 tome 1 (October 2014) . - pp 6205 - 6215 Titre : On the SAR backscatter of burned forests: a model-based study in C-Band, over burned pine canopies full text Type de document : Article/Communication Auteurs : Vasileios kalogirou, Auteur ; P. Ferrazzoli, Auteur ; Andrea Della Vecchia, Auteur ; Michael Foumelis, Auteur Année de publication : 2014 Article en page(s) : pp 6205 - 6215 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] forêt [Termes IGN] Grèce [Termes IGN] image C-SAR [Termes IGN] impact sur l'environnement [Termes IGN] incendie de forêt [Termes IGN] modèle de transfert radiatif [Termes IGN] rétrodiffusion Résumé : (Auteur) A discrete scattering model, based on the radiative-transfer theory, is used to simulate the backscattering of burned pine canopies at C-band. The model is first parameterized either with direct field measurements on a selected burned area in Greece or with proper estimations of the required variables, for which direct measurements were not possible. The simulated backscatter at VV polarization was compared against European Remote Sensing 2 (ERS-2) observations. The comparison was based on the observed backscattering of nine burned plots, during four different postfire acquisitions (n=36). In general, the model provides satisfying estimations of the backscattering with a root-mean-square error of 1.01 dB. The copolar signal for both HH and VV showed a mild decrease with increasing fire impacts and was considerably affected by the incidence angle. From the experiments performed in the simulated environment, it is concluded that the SAR copolar (C-band) backscatter varies with respect to certain fire impact levels. Other important acquisition- or stand-dependent variables (such as incidence angle and snag age) were also found to impact the relationship between backscatter and fire impacts. Finally, the backscattering variability on increasing volumetric soil moisture (VSM) and snag moisture was examined. The increase of VSM from 20% to 30% amplified the signal in both copolarized bands by 1.2-1.5 dB. This amplification was more apparent on VV polarization than in HH polarization. Instead, the HH signal proved to be more sensitive on the increase of snag moisture, which was tested under a stable dry soil. Numéro de notice : A2014-480 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2013.2295594 En ligne : https://doi.org/10.1109/TGRS.2013.2295594 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74061 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2014101A	RAB	Revue	Centre de documentation	En réserve L003	Disponible