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Optimization of Geodynamic Network on the Argentina Islands Neighbouring Vernadsky Antarctic Station
K.R.Tretyak
National University “Lvivska Polytechnika”
Abstract
According to the results of paleomagnetic, magnetometric and geological-tectonic researches there are obtained considerable differences in the tectonic structure of the archipelago Argentina islands. Geodetic methods, namely local GPS-networks can add and provide with new information about modern geodynamics of the Antarctic Peninsula. Mainly it concerns to the territory of Argentina Islands contiguous to Ukrainian Antarctic station “Academic Vernadskyy”. With this purpose in the frame of seasonal 8-th Ukrainian Antarctic expedition (February-March 2003) in the district of Antarctic station “Academic Vernadskyy” it was created the precise geodetic network of ambient islands by the join efforts of scientists of National University “Lvivska Politechnika” (K. Tretyak, V. Glotov) and Close Corporation “ECOMM” (J. Ladanovskyy, P. Bahmach). The network was developed not only with purpose to study the deformations and movements of the earth’s crust on the territory of Antarctic peninsula but also for creation of control geodetic network for implementation of topographical-geodetic works on the station “Academic Vernadskyy” which is located in the north part of Antarctic peninsula (south latitude B=65015’, western longitude L=64015’).
Created geodynamic network covers north-eastern contiguous in the radius of 15 kilometers islands and the part of continent. The network is based on 8 geodetic station. The centers of stations are seated in the basement of rocks. The eccentricities of antennas of the phase centers were determined simultaneously on the special hard base for receivers Leica SR-399 , SR-9500 and Trimble 4600LS before the beginning of observations.
The measurements were implemented from 12 to 28 of February with use of three double frequency GPS-receivers (firm Trimble 4800 and firm Leica SR-399 and SR9500) and single frequency receiver Trimble 4600LS. Receiver Trimble 4800 was working during all time on the station VER1 in the mode of temporary permanent station. Duration of vectors measurements varies from 2 to 12 hours depending on weather conditions and transport limitation. For increasing of trustworthiness and accuracy of determination of station coordinates in the measured vectors it were applied the correction of eccentricities of the phase centers of GPS-antennas and it was fulfilled a posteriori network optimization.
In the result of considering of eccentricities of the phase centers of GPS-antennas and a posteriori network optimization the maximum errors of determination of plane coordinates of stations decreases from 5,7mm to 4,3 mm, and mean error from 2,9mm to 2,4mm. Maximum error of altitude determination decreases from 7,3 to 5,5 mm, and mean error from 3,9 to 3,2 mm. In percentage ratio maximum errors decrease on 25% and mean errors on 15%. Optimized network is more homogenous according to the accuracy.
It should be mentioned that relative error of determination of vector of station displacement after implementation of equal according to accuracy next circle will be approximately 3*10-7 . Taking into account that values of velocity of the earth surface deformations in the plane and seismic not active regions is 10-7 1/year and in mountain region is 10-6-10-5 1/year, then already in the next year on the assumption of repeated measurements it can be obtained the reliable quantitative parameters of passing of modern deformation processes in this region. It will allow to improve the modern regional geodynamic model of Antarctic peninsula.
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