Studies of recent vertical crustal movements at the territories insufficiently provided with relevelling data

Abstract

Morphological investigations play an increasing role in the study of vertical crustal movements in regions where there are insufficient geodetic data. The data from repeated levellings are controlled and supplemented by the results of special geomorphological studies which permit judgements on the significance and probable rate of recent crustal movements. In the USSR a number of geomorphological methods have been developed and used to study recent crustal movements. Among these are measurements of anomalous slopes of river networks, modern dynamics of fluvial processes and the depth at which the groundwater level occurs. The application of statistical methods allows the rate of recent movements (υ) to be evaluated. It is advisable to use linear equations of multiple regression of the following type: V h, i … = a 0 + a 1 h + a 2 i + … a n s where V h, i is the mean probable value of the rate of movement; h, i, s are various geomorphological indices of recent movements. A high degree of correlation between the values of the rate of recent crustal movements calculated from geodetic data and the geomorphological indices ( h, i, s) has been established. In regions with a dense network of repeated levelling lines, the mean quadratic error of the calculated value of V, using geomorphological data, ranges from ±0.7 to ±1.3 mm/year, and the correlation coefficient between V and geomorphological indices reaches 0.8. A set of geomorphological indices of recent crustal movements has been obtained by observing features in the region which is being studied.