Centre de documentation
scientifique

Horizontal and vertical interseismic velocity fields in the Vanuatu subduction zone from GPS measurements: Evidence for a central Vanuatu locked zone / Nicolas Bergeot in Journal of geophysical research : Solid Earth, Vol 114 n° B6 (June 2009)    

Public [article]  inJournal of geophysical research : Solid Earth > Vol 114 n° B6 (June 2009) . - 20 p. Titre : Horizontal and vertical interseismic velocity fields in the Vanuatu subduction zone from GPS measurements: Evidence for a central Vanuatu locked zone Type de document : Article/Communication Auteurs : Nicolas Bergeot, Auteur ; Marie-Noëlle Bouin , Auteur ; Michel Diament , Auteur ; Bernard Pelletier, Auteur ; M. Régnier, Auteur ; Stéphane Calmant, Auteur ; Valérie Ballu, Auteur Année de publication : 2009 Article en page(s) : 20 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] champ de vitesse [Termes IGN] coordonnées GPS [Termes IGN] subduction [Termes IGN] tectonique des plaques [Termes IGN] Vanuatu Résumé : (auteur) We analyzed interseismic velocity fields along the Vanuatu arc subduction zone from more than 45 GPS station measurements spanning 15 years. Convergence with respect to the Australian plate (AP) is normal to the trench, with amplitudes that vary greatly from a maximum of 170 mm a−1 at Vanikoro to 27 mm a−1 facing the D'Entrecasteaux Ridge (DER). Motions expressed relative to the Pacific plate (PP) highlight arc segmentation. Both the northern and southern segments undergo back‐arc spreading in a roughly NE‐SW direction, rotating anticlockwise and clockwise, respectively, while the central block moves eastward at a faster rate with respect to the PP than to the AP. More convergence is therefore accommodated at the eastern bound of the arc than at the Vanuatu trench. A right lateral strike‐slip movement (26 ± 1 mm a−1) along a zone normal to the trench (direction N70°) is necessary to accommodate the rate variation between the central and southern parts of the arc. Horizontal and vertical rates indicate partitioning between Malekula–southernmost Santo and central‐northern Santo blocks. Simple elastic modeling of the interseismic stage deformation gives locked zone characteristics (25° dip and 50 km width) and a 54 mm a−1 long‐term convergence rate between the AP and the central part of the Vanuatu arc from GPS horizontal and vertical velocities estimated south of the DER. The modeling does not fit the observed velocities facing the DER, probably because it does not account for the inelastic deformation associated with buoyant ridge subduction and back‐arc thrusting. Numéro de notice : A2009-586 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2007JB005249 Date de publication en ligne : 23/06/2009 En ligne : https://doi.org/10.1029/2007JB005249 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90613 [article]

Documents numériques

en open access Horizontal and vertical interseismic velocity fields ... - pdf éditeur Adobe Acrobat PDF

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]