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International audience; Structural inheritance is one of the key factors commonly proposed to control the localization of strain and seismicity in continental intraplate regions, primarily on the basis of a first‐order spatial correlation between seismicity and inherited tectonic structures. In this paper, we present new GPS (Global Positioning System) velocity and strain rate analyses that provide strong constraints on the magnitude and style of present‐day strain localization associated with the inherited tectonic structures of the Saint Lawrence Valley, eastern Canada. We analyze 143 continuous and campaign GPS stations to calculate velocity and strain rate patterns, with specific emphases on the combination of continuous and campaign velocity uncertainties, and on the definition of robustness categories for the strain rate estimations. Within the structural inheritance area, strain rates are on average 2–11 times higher than surrounding regions and display strong lateral variations of the style of deformation. These GPS velocity and strain rate fields primarily reflect ongoing glacial isostatic adjustment (GIA). Their comparison with GIA model predictions allows us to quantify the impact of the structural inheritance and the associated lithosphere rheology weakening. Outside of the major tectonic inheritance area, GPS and GIA model strain rates agree to first order, both in style and magnitude. In contrast, the Saint Lawrence Valley displays strong strain amplification with GPS strain rates 6–28 times higher than model‐predicted GIA strain rates. Our results provide the first quantitative constraints on the impact of lithospheric‐scale structural inheritance on strain localization in intraplate domains.

International audience; Over the next decade, the IVS is on the cusp of dramatic changes transitioning from using large, slow moving antennas observing at S/X (``legacy'' systems) to using small, fast antennas with broad-band receivers, the so-called VGOS systems. Never has there been a time when so many antennas specifically designed for geodetic VLBI are scheduled to come on line in such a short period. VGOS observing will change all aspects of VLBI, from scheduling, to correlation, to observing strategy, to analysis. Compared to current observing, a typical VGOS session will have 1-2 orders of magnitude more data. In this strategic plan we outline some of the operational concepts of VGOS observing, our goals for data accuracy and latency, and some of the challenges and issues we will face during this transition.

International audience; Source structure has long been recognized as a significant risk factor for the broadband method. The issue of greatest concern is that structure related phases and delays will lead to cycle slips during broadband phase connection. These errors are subtle to detect and difficult or impossible to correct after the fact. As the advent of VGOS operations draws near, criteria will be needed to generate lists of candidate VGOS sources that are at the same time strong enough to be detected and simple enough not to cause broadband phase connection errors. The purpose of this study is to propose useful VGOS source selection criteria and to understand their relation to broadband frequency sequences, source lists, and geodetic/astrometric performance. In order to increase the number of available sources, an attempt will be made to find frequency sequences that operate reliably below the typical VGOS flux cut-off of 250 mJy. Candidate source lists will be generated using the Bordeaux VLBI Image Data Base (BVID) as input.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:23:31Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:46:11Z : No. of bitstreams: 1 2-s2.0-49549113581.pdf: 229579 bytes, checksum: 76b17fc5c29077605f7976ea2b7113b6 (MD5) Made available in DSpace on 2014-05-27T11:23:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-04-01 The Brazilian Geodetic Network started to be established in the early 40's, employing classical surveying methods, such as triangulation and trilateration. With the introduction of satellite positioning systems, such as TRANSIT and GPS, that network was densified. That data was adjusted by employing a variety of methods, yielding distortions in the network that need to be understood. In this work, we analyze and interpret study cases in an attempt to understand the distortions in the Brazilian network. For each case, we performed the network adjustment employing the GHOST software suite. The results show that the distortion is least sensitive to the removal of invar baselines in the classical network. The network would be more affected by the inexistence of Laplace stations and Doppler control points, with differences up to 4.5 m. Universidade Estadual Paulista (UNESP), São Paulo University of New Brunswick - UNB, Saint John, NB Geodetic Survey Division of Natural Resources Canada - GSD Universidade Estadual Paulista (UNESP), São Paulo

chapter in book series "International Association of Geodesy Symposia" book "Observing our Changing Earth" ISBN 978-3-540-85425-8; International audience; From October 2003 to September 2005, the International VLBI Service for Geodesy and Astrometry (IVS) examined current and future requirements for geodetic VLBI, including all components from antennas to analysis. IVS Working Group 3 ‘VLBI 2010', which was tasked with this effort, concluded with recommendations for a new generation of VLBI systems. These recommendations were based on the goals of achieving 1 mm measurement accuracy on global baselines, performing continuous measurements for time series of station positions and Earth orientation parameters, and reaching a turnaround time from measurement to initial geodetic results of less than 24 hours. To realize these recommendations and goals, along with the need for low cost of construction and operation, requires a complete examination of all aspects of geodetic VLBI including equipment, processes, and observational strategies. Hence, in October 2005, the IVS VLBI2010 Committee (V2C) commenced work on defining the VLBI2010 system specifications. In this paper we give a summary of the recent progress of the VLBI2010 project.

International audience; In October 2003, the International VLBI Service for Geodesy and Astrometry (IVS) in- stalled Working Group 3 ‘VLBI2010' to examine current and future requirements for geodetic/astrometric VLBI including all components from antennas to analysis, and to create recommendations for a new gen- eration of VLBI systems. Some important recommendations include: the use of larger networks; the use of smaller faster slewing antennas; the use of very high data rates; and, the use of multiple (e.g. 4) widely spaced bands to resolve RF phase ambiguities. When taken together, these recommendations result in a many-fold increase in the number of observations per session. UV coverage improves to the point where precise VLBI images of the ICRF sources can be constructed on a daily basis directly from the geodetic observations, therefore enabling source structure corrections to be calculated. Simulations are currently underway to evaluate the potential of this approach.