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Investigating tropospheric effects and seasonal position variations in GPS and DORIS time-series from the Nepal Himalaya / Mireille Flouzat in Geophysical journal international, vol 178 n° 3 (September 2009)  

Public [article]  inGeophysical journal international > vol 178 n° 3 (September 2009) . - pp 1246 - 1259 Titre : Investigating tropospheric effects and seasonal position variations in GPS and DORIS time-series from the Nepal Himalaya Type de document : Article/Communication Auteurs : Mireille Flouzat, Auteur ; Pierre Bettinelli, Auteur ; Pascal Willis , Auteur ; Jean-Philippe Avouac, Auteur ; Thierry Héritier, Auteur ; Umesh Gautam, Auteur Année de publication : 2009 Projets : 1-Pas de projet / Article en page(s) : pp 1246 - 1259 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] données DORIS [Termes IGN] données GPS [Termes IGN] Himalaya [Termes IGN] propagation troposphérique [Termes IGN] série temporelle [Termes IGN] variation saisonnière Résumé : (auteur) Geodetic time-series from continuous GPS (cGPS) and 1 DORIS stations across the Himalaya of central Nepal show strong seasonal fluctuations observed on the horizontal and vertical components. Because the fluctuations determined at the different stations have similar phase but different amplitudes, these observations would imply that the secular shortening across the range is modulated by a seasonal strain. Given the geographic and climatic setting, there is however a possibility that the GPS positions be biased by tropospheric effects. We process these data using two different software packages and two different analysis strategies. Our analysis shows evidence for 1-strong seasonal fluctuation of zenithal delays consistent with in situ meteorological data and two strong horizontal tropospheric gradients in particular in the EW direction, that is, parallel to the mountain front at Gumba, also detected in DORIS results. We show that the tropospheric effects cannot however be the source of the observed seasonality of horizontal strain. This study supports the view that the seasonal strain in the Himalaya is real and probably driven by seasonal surface load variations. Our study adds support to the view that seasonal variations of seismicity in the Himalaya reflects seasonal variations of geodetic strain. Numéro de notice : A2009-604 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1365-246X.2009.04252.x En ligne : https://doi.org/10.1111/j.1365-246X.2009.04252.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95755 [article]

Plate Motion of India and Interseismic Strain in the Nepal Himalaya from GPS and DORIS Measurements / Pierre Bettinelli in Journal of geodesy, vol 80 n° 8-11 (November 2006)  

Public [article]  inJournal of geodesy > vol 80 n° 8-11 (November 2006) . - pp 567 - 589 Titre : Plate Motion of India and Interseismic Strain in the Nepal Himalaya from GPS and DORIS Measurements Type de document : Article/Communication Auteurs : Pierre Bettinelli, Auteur ; Jean-Philippe Avouac, Auteur ; Mireille Flouzat, Auteur ; F. Jouanne, Auteur ; Laurent Bollinger, Auteur ; Pascal Willis , Auteur ; Gyani Raja Chitrakar, Auteur Année de publication : 2006 Article en page(s) : pp 567 - 589 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] déformation de la croute terrestre [Termes IGN] données DORIS [Termes IGN] données GPS [Termes IGN] Himalaya [Termes IGN] tectonique des plaques Résumé : (auteur) We analyse geodetically estimated deformation across the Nepal Himalaya in order to determine the geodetic rate of shortening between Southern Tibet and India, previously proposed to range from 12 to 21 mm yr−1. The dataset includes spirit-levelling data along a road going from the Indian to the Tibetan border across Central Nepal, data from the DORIS station on Everest, which has been analysed since 1993, GPS campaign measurements from surveys carried on between 1995 and 2001, as well as data from continuous GPS stations along a transect at the logitude of Kathmandu operated continuously since 1997. The GPS data were processed in International Terrestrial Reference Frame 2000 (ITRF2000), together with the data from 20 International GNSS Service (IGS) stations and then combined using quasi- observation combination analysis (QOCA). Finally, spatially complementary velocities at stations in Southern Tibet, initially determined in ITRF97, were expressed in ITRF2000. After analysing previous studies by different authors, we determined the pole of rotation of the Indian tectonic plate to be located in ITRF2000 at 51.409±1.560° N and −10.915±5.556°E, with an angular velocity of 0.483±0.015°. Myr−1. Internal deformation of India is found to be small, corresponding to less than about 2 mm yr−1 of baseline change between Southern India and the Himalayan piedmont. Based on an elastic dislocation model of interseismic strain and taking into account the uncertainty on India plate motion, the mean convergence rate across Central and Eastern Nepal is estimated to 19±2.5 mm yr−1, (at the 67% confidence level). The main himalayan thrust (MHT) fault was found to be locked from the surface to a depth of about 20 km over a width of about 115 km. In these regions, the model parameters are well constrained, thanks to the long and continuous time-series from the permanent GPS as well as DORIS data. Further west, a convergence rate of 13.4±5 mm yr−1, as well as a fault zone, locked over 150 km, are proposed. The slight discrepancy between the geologically estimated deformation rate of 21±1.5 mm yr−1 and the 19±2.5 mm yr−1 geodetic rate in Central and Eastern Nepal, as well as the lower geodetic rate in Western Nepal compared to Eastern Nepal, places bounds on possible temporal variations of the pattern and rate of strain in the period between large earthquakes in this region. Numéro de notice : A2006-673 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0030-3 Date de publication en ligne : 08/03/2006 En ligne : https://doi.org/10.1007/s00190-006-0030-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102742 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-06102	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-06101	RAB	Revue	Centre de documentation	En réserve L003	Disponible