Chapter 6 



EVALUATING THE ACCURACY OF A GRAVIMETRIC 



SURVEY, SELECTING THE RATIONAL DENSITY OF THE 



OBSERVATION NETWORK AND CROSS-SECTIONS OF 



ISOANOMALIES OF THE FORCE OF GRAVITY 



B. V. KOTLIAREVSKII 



In planning gravimetric work, the density of the network of observations 

 is selected with regard to the geological problems and the expected character 

 of the gravimetric field. Normally no calculations are carried out and the 

 selection of the network is mainly based on previous experience. 



The cross -section of isoanomalies planned in areal surveys is determined 

 as the function of the expected mean square error for the values of the 

 force of gravity at consecutive points. The actual value of this error obtained 

 after carrying out field work is considered as a measure of the accuracy of 

 the survey. 



Methods of selecting the observation network and evaluating the accuracy 

 of the survey are of course imperfect. They do not make it possible to solve 

 the basic problem, arising in the planning of the work, which is to find 

 the optimal technical and economic solution of the geological problem 

 in the gravimetric survey. The problem consists in predicting the density 

 of the network and the accuracy of the observations, which will ensure the 

 detection of the features of the field with the required accuracy. 



It is therefore not by accident that the accuracy of the survey and the 

 choice of a rational network of observations have been studied both in this 

 country and abroad. We mention in particular the work of Andreev<1) 

 and LuKAVCHENKO (^), who determined the density of the network as a function 

 of the value and extent of the anomahes, caused by certain geometrically 

 regular bodies; the work of Bulanzhe (2), devoted to the problems of accuracy 

 of survey, selection of the rational section of isoanomalies and the scale of 

 the geophysical map under conditions which permit linear interpolations 

 between the points of observations; finally, a number of recent art- 

 icles by VoLODARSKii <^\ Grushinskii (^), Malovichko (^) and Puzyrev(^) 

 who consider from another point of view the various facets of the problem 

 of the density of the network, the accuracy of constructing from isolines, etc. 



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