| Summary: | In mountains regions, the effect of vertical deflections appreciably exceeds the accuracy of most geodetic measurements and causes systematic errors of some cm per km at steep sightings. Therefore, crustal movements may be veiled by the enlarged error ellipses. The paper presents a possibility of determining vertical deflections in a high-mountain region by means of using a simple and rapid graphical method. During five minutes it is possible to determine the topographical deflections of the vertical with the accuracy of ±(1 - 2)½ using explicit mathematical equations and a simple topographical map. The mathematical correction for very asymmetrical peaks by-valleys and irregular slopes are given. No astronomical and geodetic observations or digital height models are necessary. Concluding an example from West Tatras (part of High Tatras) is shown, where the method could be compared with exact values of meridian and transversal vertical deflection elements at 6 points. The exact values of meridian and transverse vertical deflection elements were obtained from the astronomical and geodetic measurements in astronomical-geodetic network in 1961-62. The area covers 4x12 km and heights between 1200 m and 2300 m. The slopes have mean inclination of 40-80 % (maximum 180 %). Because of the steep slopes, a valley fork and the asymmetric mountainsides to the next valleys (8 km), the example is an extreme one.The obtained results in vertical deflections confirm the presented so called rapid graphic method as a new possibility in determining relative, i.e. astronomical-geodetic vertical deflections. The graphic method is very simple, rapid and it is not necessary to use any geodetic equipment. Just a topographic map, drawing instruments, and a vest-pocked computer can be enough for determining the vertical deflection during 2-5 minutes.
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