ALBERT

Description: Abstract

Description: The Austrian Geoid 2008 is the official geoid model for Austria provided by the Austrian Federal Office for Metrology and Surveying (BEV). This model describes the transformation surface (EPSG:9276) between ellipsoidal heights w.r.t. the GRS80 ellipsoid (EPSG:4937) and orthometric heights (EVRF2000 Austrian, EPSG:9274). The grid is defined in ETRS89 (EPSG:4258), covering the area within 46.3° 〈 latitude 〈 49.1° and 9.5° 〈 longitude 〈 17.3°, with a spacing of 1.5' in latitude and 2.5' in longitude. The model is based on 14001 gravity anomaly values, 672 deflections of the vertical and 170 GPS/levelling observations. The computation was performed in the framework of a remove-restore procedure, modelling the long wavelengths of the gravity field by the EIGEN-GL04S global model, and the short wavelengths by the Airy-Heiskanen model with a standard density of 2670 kg/m3. A digital terrain model with a resolution of 44 x 49 m was assembled as a combination of regional Austrian and Swiss models, as well as SRTM for the neighboring countries. The Least Squares Collocation (LSC) technique was used for the geoid computation, interpolating the empirical covariance of the residual quantities by the Tscherning-Rapp analytic covariance model. Special care was devoted to the optimal relative weighting of the input data, namely to the noise covariance models, especially concerning the GPS/levelling observations. The resulting hybrid geoid model was assessed by comparing it with independent GPS/levelling information, leading to an estimated accuracy of the order of 2-3 cm over the whole Austrian territory. The model is also available at the BEV open data portal, and more information about it can be found on the BEV website. The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.

Description: Other

Description: The International Service for the Geoid (ISG) was founded in 1992 (as International Geoid Service - IGeS) and it is now an official service of the International Association of Geodesy (IAG), under the umbrella of the International Gravity Field Service (IGFS). The main activities of ISG consist in collecting, analysing and redistributing local and regional geoid models, as well as organizing international schools on the geoid determination (Reguzzoni et al., 2021).

Description: Abstract

Description: The Austrian Geoid 2008 is the official geoid model for Austria provided by the Austrian Federal Office for Metrology and Surveying (BEV). This model describes the transformation surface (EPSG:9277) between ellipsoidal heights w.r.t. the Bessel ellipsoid (datum MGI, EPSG:9267) and orthometric heights (EVRF2000 Austrian, EPSG:9274). The grid is defined in MGI (EPSG:4312), covering the area within 46.3° 〈 latitude 〈 49.1° and 9.5° 〈 longitude 〈 17.3°, with a spacing of 1.5' in latitude and 2.5' in longitude. The model is based on 14001 gravity anomaly values, 672 deflections of the vertical and 170 GPS/levelling observations. The computation was performed in the framework of a remove-restore procedure, modelling the long wavelengths of the gravity field by the EIGEN-GL04S global model, and the short wavelengths by the Airy-Heiskanen model with a standard density of 2670 kg/m3. A digital terrain model with a resolution of 44 x 49 m was assembled as a combination of regional Austrian and Swiss models, as well as SRTM for the neighboring countries. The Least Squares Collocation (LSC) technique was used for the geoid computation, interpolating the empirical covariance of the residual quantities by the Tscherning-Rapp analytic covariance model. Special care was devoted to the optimal relative weighting of the input data, namely to the noise covariance models, especially concerning the GPS/levelling observations. The resulting hybrid geoid model was assessed by comparing it with independent GPS/levelling information, leading to an estimated accuracy of the order of 2-3 cm over the whole Austrian territory. The model is also available at the BEV open data portal, and more information about it can be found on the BEV website. The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.

Description: Other

Description: The International Service for the Geoid (ISG) was founded in 1992 (as International Geoid Service - IGeS) and it is now an official service of the International Association of Geodesy (IAG), under the umbrella of the International Gravity Field Service (IGFS). The main activities of ISG consist in collecting, analysing and redistributing local and regional geoid models, as well as organizing international schools on the geoid determination (Reguzzoni et al., 2021).

Description: Abstract A semi-permanent GPS network of about 30 vertices: Victoria Land Network for DEFormation control (VLNDEF) has been set up since Austral summer 1998 at Terra Nova Bay (TNB) near Ross Sea in Antarctica. A permanent GPS station TNB1 based on dual frequency Ashtech P-code GPS receiver with a Choke Ring Antenna has been installed on a bedrock monument in October 1998 and has recorded continuously up to the present. The GPS network has been routinely surveyed every two summers using high quality dual frequency GPS receivers; data, metadata and solutions are available to the scientific community at (http://www.geodant.unimore.it). In this paper we present the results of a distributed session approach applied to processing GPS data of the VLNDEF network, and based on Gamit/Globk 10.3 GPS analysis software. An improved reference frame definition was implemented using Globk package in order to compute Antarctic intra-plate residual velocities and to invert the strain field from GPS data in this region.

Description: Scientific Committee on Antarctic Research (SCAR) International Arctic Science Committee (IASC)

Description: Published

Description: St. Petersburg, Russia

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: reserved

Description: Le reti permanenti GPS costituiscono una importante risorsa per una serie di studi tecnologici e scientifici. La carenza di conoscenze in studi di tettonica attiva, che comprendono anche la parte di sismologia come l'accumulo di deformazione sulle faglie, è stata a lungo frenata dalla mancanza di reti permanenti GPS sufficientemente dense distribuite su tutto il territorio nazionale. In particolare, la definizione di una placca Adriatica e la sua terminazione meridionale sono ancora materia di dibattito (Oldow et al., 2002; Battaglia et al. 2004). Inoltre, di recente, alcuni importanti lavori (Hollenstein, et al. 2004; D'Agostino and Selvaggi; Serpelloni et al. 2005) hanno mostrato che valori di deformazione molto più alti di quanto si pensava prima sono stati effettivamente riscontrati nella nostra regione e che solo l'uso di una rete densa di stazioni, quindi di un campionamento ad alta densità nelle aree dove sono maggiori le velocità relative, permette di osservare in modo corretto il rilascio, o accumulo, di deformazione. Infine, il contributo della geodesia alla sismologia sta diventando sempre più importante sia nella definizione del rilascio cosismico durante un terremoto e sia nell'osservazione e modellazione dell'accumulo intersismico di deformazione elastica su faglie attive. Da qualche anno, l'Istituto Nazionale di Geofisica e Vulcanologia (INGV) ha impiegato notevoli risorse e sforzi per rispondere a tali temi scientifici. Selvaggi et al. (2006) hanno gettato le basi e mostrato i primi sviluppi di una rete GPS permanente, la Rete Integrata Nazionale GPS (RING), creata con l'obiettivo di dare un forte contributo scientifico ai temi sopra citati La rete RING (Fig. 1a), nella sua completezza, rappresenta ad oggi non solo un punto di riferimento per studi di carattere scientifico ma anche una robusta infrastruttura tecnologica e informatica per l'archiviazione dei dati GPS per diverse altre reti locali e regionali (Regione Puglia, Regione Friuli, Leica Geosystems). Tali reti, contribuiscono quotidianamente all'acquisizione, all'interno di un server, di dati per un totale di oltre 300 stazioni distribuite sul territorio nazionale (Fig. 1b). Se, poi, si considera anche l'aspetto del processamento dei dati GPS, l'utilizzo di dati GPS appartenenti ad altre reti (locali, regionali o anche esterne al territorio italiano) fa sì che ogni analista utilizzi i dati, in media, di circa 650 stazioni GPS permanenti al giorno.

Description: Published

Description: L'Aquila - Italia

Description: 1.9. TTC - Rete GPS nazionale

Description: reserved

Description: Within the aim to evaluate the present day crustal deformation of central western Mediterranean and northern Africa, a regional GPs network was planned and measured in the frame of the Tyrgeonet and Algeonet projects. We analyse GPS data collected at ten geodetic monuments located in Algeria, together with the Villafranca, Roquetes, Cagliari, Matera and Noto IGS permanent stations. This GPS network is deployed in a crucial area for the comprehension of the Western Mediterranean geodynamics, being located along the collision belt between the Eurasian and African plates. Moreover, some of the Algerian stations are located in the inner Algeria, along the Atlas deformed zone that released strong seismic events in the past, not yet studied by space based geodetic techniques. Other four stations are located in the tectonically stable of the Algerian erg. In this paper we describe the network and the data analysis of the first epoch surveys performed during june 1998.

Description: Published

Description: 179-192

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: JCR Journal

Description: open

Description: The Messina Straits, southern Italy, unfortunately became famous after the occurrence of the great earthquake of December 28, 1908, Ms=7.5, that caused thousands of deaths and severe destruction over a wide area along the Sicilian and Calabrian coasts. After that time many geophysical and geological studies were performed to evaluate the seismic characteristics of the 1908 eartquake, the seismic risk and the geological evolution of this region in the framework of Mediterranean geodynamics. In 1970, a geodetic network was set up across the Straits and was repeatedly measured with terrestrial techniques until 1980, showing a northward displacement of the Sicilian sites with respect to the Calabrian ones, between 1970 and 1971. In 1987, the old terrestrial network was surveyed again for the first time by the GPS technique, improving the accuracy of the coordinate determinations. Finally, in 1994, a wider network was established and surveyed again to collect additional GPS observations from a larger area across the Straits. In this paper, an analysis of the results obtained from the two GPS surveys with respect to those achieved by the terrestrial surveys (from 1970 to 1980) is given. This analysis shows there has not been significant crustal horizontal deformation across the Straits in the last 15 years. Although this crustal tectonic 'quiescence' corresponds to a low seismic activity level in the Straits area, terrestrial and GPS geodetic results would agree with Straits geophysical models excluding any aseismic deformations acting perpendicular to the Straits axis.

Description: Published

Description: 85-97

Description: 1.8. Osservazioni di geofisica ambientale

Description: JCR Journal

Description: reserved

Description: The Calabria region has been characterised for a lot of geodynamic phenomena and a complex Geoid. This zone is a very interesting zone for geophysical and geodetic studies. In 1993 has been effectuated a GPS survey. This work shows the quality of the results and a comparison between GPS Geoid and the Italian Gravimetric Geoid performed by Politecnico di Milano.

Description: Published

Description: 1-375

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: open

Description: In order to investigate the dynamic processes actually in progress in the Aeolian Islands a volcanic area in Southern Italy, high precision geodetic observations are employed. the knowledge of the kinematic field (vertical and horizontal displacements) and of the time-space gravity variations is an important constrain for any model describing the geodynamic processes involving the investigated area. Gravimetric (absolute, relative and gradiometric), photogrammetric, altimetric and GPS surveys are periodically carried out on networks spanning over the whole aeolian archipelagus. Recently a GPS network has been designed and surveyed to obtain a more complete knowledge of the kinematic field taking place in the area. This will improve the understanding of the tectonic processes acting in the area. The result of the interdisplinary approach are presented and discussed.

Description: Published

Description: 33-50

Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive

Description: reserved

Description: The recent development of the Global Positioning System geodetic technique allow the determination of the separation between the ellipsoid and the geoid if GPS-derived elevations are compared with spirit leveling measurements; this approach may provide a contribution to the definition of the geoidal ondulation even on areas such as the Italian peninsula characterized by wide roughness of topography and very complex geological and structural features. With this aim in 1993 we measured by the GPS technique the position of 32 benchmarks along some of the Italian first order leveling routes located across the Apenninic chain. The simultaneous surveys performed on ITRF stations and on 5 tide gauge stations, may provide an accurate constrain of the gravimetric geoid recently computed by DIIAR in Milan, Italy.

Description: Published

Description: 72-80

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: reserved

Description: Normalmente en los levantamientos geodésicos se utilizan dos tipos de referencias: las coordenadas de origen y el datum vertical: Las primeras están en función del elipsoide o superficie matemática de referencia que más se ajusta al área, y el segundo; por la determinación del nivel medio del mar con 19 años de observación. El Ecuador tiene como elipsoide de referencia, el Internacional y el datum horizontal del punto localizado en la Canoa, Venezuela (Provisional South American Datum 1956, PSAD 56), cuya coordenadas han sido transportadas a nuestro país mediante redes geodésicas. En 1948, el Ecuador instaló una estación mareográfica en la Libertad (Lat. 020° 12'S., Long. 80° 55'W) y a la determinación del datum vertical se refiere el presente trabajo.

Description: Incl. ref.bibl., grafs.

Description: Published

Description: Scientific investigations in Antarctica are, for many different reasons, a challenging and fascinating task. Measurements, observations and field operations must be carefully planned well in advance and the capacity of successfully meeting the goals of a scientific project is often related to the capacity of forecasting and anticipating the many different potential mishaps. In order to do that, experience and logistic support are crucial. On the scientific side, the team must be aware of its tasks and be prepared to carry out observations in a hostile environment: both technology and human resources have to be suitably selected, prepared, tested and trained. On the logistic side, nations, institutions and any other organisation involved in the expeditions must ensure the proper amount of competence and practical support. The history of modern Italian Antarctic expeditions dates back to the middle 80’s when the first infrastructures of “Mario Zucchelli Station”, formerly Terra Nova Bay Station, were settled at Terra Nova Bay, Northern Victoria Land. Only a few years later, the first geodetic infrastructures were planned and built. Italian geodetic facilities and activities were, ever since, being constantly maintained and developed. Nowadays, the most remarkable geodetic infrastructures are the permanent Global Positioning System (GPS) station (TNB1) installed at Mario Zucchelli and the GPS geodetic network Victoria Land Network for DEFormation control (VLNDEF) entirely deployed on an area extending between 71° S and 76° S and 160° E and 170° E. These facilities do not only allow carrying out utmost geodetic investigations but also posses interesting capacities on the international multidisciplinary scientific scenario. In order to fully exploit their potentiality, management and maintenance of the infrastructure are crucial; nevertheless, in order to perform high quality scientific research, these abilities must be coupled with the knowledge concerning a proper use and a correct processing of the information that these infrastructures can provide. This work focuses on the different methods that can be applied to process the observations that are performed with GPS technique in Northern Victoria Land, aiming at reaching the highest accuracy of results and assuring the larger significance and versatility of the processing outcomes. Three software were used for the analysis, namely: Bernese v.5.0, Gipsy/Oasis II and Gamit/Globk. The working data sets are (i) the permanent GPS station TNB1 observations continuously performed since 1998 and (ii) the five episodic campaigns performed on the sites of VLNDEF. The two infrastructures can be regarded as neat examples of standard geodetic installation in Antarctica. Therefore, the technological solutions that were adopted and applied for establishing the GPS permanent station and the VLNDEF geodetic network as well as the data processing strategies and the data analysis procedures that were tested on their observation will be illustrated in detail. The results will be presented, compared and discussed. Furthermore, their potentials and role in geodetic research will be carefully described; their versatility will also be highlighted in the foreground of a multidisciplinary Antarctic international scientific activity.

Description: Published

Description: 37-72

Description: 1.8. Osservazioni di geofisica ambientale

Description: reserved