140 B. V. KOTLIAREVSKII 



In the present article, an attempt is made to solve these problems in a suffi- 

 ciently general from, taking into account the errors in observation and inter- 

 polation. The proposed method of evaluating the accuracy of a gravimetric 

 survey, of the determining the rational density of the network and of select- 

 ing the cross-section of isoanomalies is basically suitable for any type of 

 survey. However, it has been mainly developed for the commonest types of 

 regional and exploratory surveys. With regard to detailed surveys, another 

 and somewhat different method can be recommended, which owing to the 

 lack of space is not given here. 



SELECTING THE CRITERIA FOR EVALUATING THE ACCURACY 

 OF A GRAVIMETRIC SURVEY 



The accuracy of the observed gravity field depends on the accuracy of 

 determining the values of gravity at the observation points, on the density 

 ©f the network and on the character of the field itself. Furthermore, it depends 

 on the method of interpolating the gravity values in the intervals between 

 the observation points. We have accepted the idea of linear interpolation 

 since it is universally used in gravimetric work. 



Before proceeding to the development of a method for evaluating the 

 accuracy of a gravimetric survey, it is necessary to select the basic criteria 

 for this evaluation. 



The main type of gravimetric work is areal survey the results of which 

 are represented by a map of isoanomalies of gravity. The accuracy of the map 

 can be determined from its various features. It is also possible to evaluate 

 the value for the error in the observed field; this value being the mean 

 square error in the value for gravity at a certain arbitrarily selected point 

 on the map. 



This error does not depend on the cross -section of the isoanomaly and is 

 a function of the errors of the values of gravity at the observation point, 

 the density of the network and the character of the gravity field. For a field 

 along a profile, this error (we will call it s^^ is determined by the follow- 

 ing integral equation: 



t/ 



-r / [^ (^) - ^ ((7, o, ^)] 2 dx, (1) 



where g is the true gravity field (unknown) ; g- is the observed field, which 

 depends on the mean square error a in determining the force of gravity at 

 the observation points, on the average distance a between these points and 



