Bibby, H.M. 1973 The reduction of geodetic survey data for the detection of earth deformation. [s.l.]: [s.n.]. Report / Geophysics Division 84 31 p.
Abstract: When geodetic data are analysed to determine possible movements in a region of tectonic activity, considerable benefit can be gained by the simultaneous analysis of several sets of observational data made at different times over the same area, as opposed to comparing the independently derived positions from each survey. The necessary equations for such a simultaneous reduction are derived by representing the components of the strain tensor as polynomials in isometric latitude and longitude. A variation of the rate of strain with time can also be introduced when more than one re-observation has been made of the same area. This method yields the initial position of each observation station, and the temporal and spatial variation of the shear components of strain, and if the necessary data are available, the dilatation and rotation components. When only adjusted data are available, the full analysis is not applicable and the method of Frank (1966) must be used. For a plane triangle, the standard error of the shear components of strain are proportional to the cosecants of the angles of the triangle. The standard error, which cannot be determined when only adjusted data are available, could be very large if one of the angles of the triangles were small. This problem can be avoided if compound figures are used to determine the strain (auth.)