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Trajectory models and reference frames for crustal motion geodesy / Michael Bevis in Journal of geodesy, vol 88 n° 3 (March 2014)  

Public [article]  inJournal of geodesy > vol 88 n° 3 (March 2014) . - pp 283 - 311 Titre : Trajectory models and reference frames for crustal motion geodesy Type de document : Article/Communication Auteurs : Michael Bevis, Auteur ; Abel Brown, Auteur Année de publication : 2014 Article en page(s) : pp 283 - 311 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] déformation de la croute terrestre [Termes IGN] orbite [Termes IGN] orbitographie par GNSS [Termes IGN] série temporelle Résumé : (Auteur) We sketch the evolution of station trajectory models used in crustal motion geodesy over the last several decades, and describe some recent generalizations of these models that allow geodesists and geophysicists to parameterize accelerating patterns of displacement in general, and postseismic transient deformation in particular. Modern trajectory models are composed of three sub-models that represent secular trends, annual oscillations, and instantaneous jumps in coordinate time series. Traditionally the trend model invoked constant station velocity. This can be generalized by assuming that position is a polynomial function of time. The trajectory model can also be augmented as needed, by including one or more logarithmic transients in order to account for typical multi-year patterns of postseismic transient motion. Many geodetic and geophysical research groups are using general classes of trajectory model to characterize their crustal displacement time series, but few if any of them are using these trajectory models to define and realize the terrestrial reference frames (RFs) in which their time series are expressed. We describe a global GPS reanalysis program in which we use two general classes of trajectory model, tuned on a station by station basis. We define the network trajectory model as the set of station trajectory models encompassing every station in the network. We use the network trajectory model from the each global analysis to assign prior position estimates for the next round of GPS data processing. We allow our daily orbital solutions to relax so as to maintain their consistency with the network polyhedron. After several iterations we produce GPS time series expressed in a RF similar to, but not identical with ITRF2008. We find that each iteration produces an improvement in the daily repeatability of our global time series and in the predictive power of our trajectory models. Numéro de notice : A2014-137 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0685-5 Date de publication en ligne : 05/01/2014 En ligne : https://doi.org/10.1007/s00190-013-0685-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33042 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2014031	SL	Revue	Centre de documentation	Revues en salle	Disponible

Devising stable geometrical reference frames for use in geodetic studies of vertical crustal motion / Michael Bevis in Journal of geodesy, vol 87 n° 4 (April 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 4 (April 2013) . - pp 311 - 321 Titre : Devising stable geometrical reference frames for use in geodetic studies of vertical crustal motion Type de document : Article/Communication Auteurs : Michael Bevis, Auteur ; Abel Brown, Auteur ; Eric Kendrick, Auteur Année de publication : 2013 Article en page(s) : pp 311 - 321 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] déformation verticale de la croute terrestre [Termes IGN] positionnement par GPS [Termes IGN] repère de référence Résumé : (Auteur) We present a method for constructing and assessing the stability of a geometrical reference frame for use in vertical crustal motion studies. Our approach exploits the fact that when we transform GPS velocity solutions from one reference frame (RF) to another one using a Helmert transformation, only the frame translation rate parameters produce significant changes in the vertical station velocities expressed in the final RF. Loosely speaking, one can select and impose a ‘vertical RF’ from an ensemble of candidate frames, without any reference to the ‘horizontal RF’ (which can be selected and imposed afterwards), by seeing how the frame translation rates vary as one moves across the ensemble of frames. We order this ensemble according to the number of stations, N, incorporated into the set VREF whose RMS vertical motion is minimized in order to realize each frame. The value of N controls the level of scatter in, and hence the degree of similarity between the vertical velocities of the stations composing VREF. We characterize a specific vertical RF as stable if all of the frames located in a large neighborhood of the ensemble which includes the specific frame are characterized by very small relative frame translation rates. In this case, the expression of vertical GPS station velocities in any of these frames would lead to very similar results. We present a case study using a very large global time series in which we find a large RF neighborhood in which vertical station velocities are globally stable at the ? 0.2 mm/year level, and a slightly smaller neighborhood in which vertical stability improves to ? 0.1 mm/year level in polar regions. Numéro de notice : A2013-216 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0600-5 Date de publication en ligne : 03/11/2012 En ligne : https://doi.org/10.1007/s00190-012-0600-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32354 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2013041	SL	Revue	Centre de documentation	Revues en salle	Disponible

Interseismic and coseismic motions in GPS series related to the Ms 7.3 July 13, 1994, Malekula Earthquake, Central New Hebrides Subduction Zone / Stéphane Calmant in Geophysical research letters, vol 24 n° 23 (December 1997)  

Public [article]  inGeophysical research letters > vol 24 n° 23 (December 1997) . - pp 3077 - 3080 Titre : Interseismic and coseismic motions in GPS series related to the Ms 7.3 July 13, 1994, Malekula Earthquake, Central New Hebrides Subduction Zone Type de document : Article/Communication Auteurs : Stéphane Calmant, Auteur ; Bernard Pelletier, Auteur ; Robert Pillet, Auteur ; M. Régnier, Auteur ; Pierre Lebellegard, Auteur ; Didier Maillard, Auteur ; Fred Taylor, Auteur ; Michael Bevis, Auteur ; Jacques Récy, Auteur Année de publication : 1997 Article en page(s) : pp 3077 - 3080 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] déformation de la croute terrestre [Termes IGN] Nouvelles-Hébrides [Termes IGN] séisme [Termes IGN] subduction [Termes IGN] tectonique des plaques Résumé : (auteur) On July 13, 1994, an earthquake Ms=7.3 occurred at Malekula, in the New Hebrides archipelago. The GPS data collected across the New Hebrides trench between 1990 and 1996 were processed in order to separate the interseismic and coseismic motions from the drifts related to the convergence with the Australian plate. The GPS-derived coseismic displacements at the GPS site in Malekula are 49 ± 15 mm southward, 230 ± 30 mm westward and 170 ± 37 mm downward, when the CMT-derived displacements are 50 mm southward, 210 mm westward and 150 mm downward. Taking into account the interseismic strain accumulation (25 mm/yr at the source established from historical seismicity, 7.5 mm/yr at the GPS site), the strain-free convergence rate at Malekula is 49 ± 3 mm/yr. Other GPS-derived convergence rates are 95 ± 1 mm/yr at Efate and 37 ± 2 mm/yr at Santo. These rates imply a regional right-lateral motion between the Efate and the Santo-Malekula segments. In contrast, the focal mechanism of the earthquake mostly indicates a left-lateral motion. Therefore, we hypothesize that the earthquake is related to variations in the interplate coupling along the converging boundary of the Santo-Malekula segment. Numéro de notice : A1997-124 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/97GL02962 En ligne : https://doi.org/10.1029/97GL02962 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102941 [article]