Geodetic traverse in the venezuelan Andes; 1983 field campaign and first results

Abstract

The traverse will be installed across the Andes mountains as a geodetic network ranging in elevation from 0 m at the Lake Maracaibo to 4400 m in the northern range. From the northern range, the network will descend down to the Llanos to an elevation of 300 m. The main part of the network covering the northern and the southern range has an area of about 20 km × 10 km. The northern and southern ranges are separated by the still-active Bocono Fault. The purpose of the geodetic traverse is to show, by two periods of measurements, variations of the geodetic parameters, caused by movements in the area of the Bocono Fault. After extensive preliminary investigations during the period 1980–1982, in the spring of 1983 the first field campaign, including the first measurements, was carried out. Participants in the campaign were the German groups from Hannover and Stuttgart, the Venezuelan group from the Universidad del Zulia, Maracaibo, and CIDA, Merida and IVIC from Caracas. The Stuttgart group was mainly occupied in observing the distances, directions and zenith angles in the network. At the same time, the Hannover group made the high-precision astronomic gravimetric measurements. All the observations were made in cooperation with the Venezuelan partners. From the autumn of 1983 to the spring of 1984, the first analysis was carried out. The Stuttgart group was responsible for the calculation of two- and three-dimensional coordinates of the points and the determination of local deflections of the vertical. By means of different models, it was also possible to calculate the effect of atmospheric refraction. The Hannover group took over the analysis of the astronomic gravimetric measurements. This paper deals mainly with the contribution of the Stuttgart group and its Venezuelan partners.