Movimenti recenti nell'Italia nord-orientale da ripetizioni di livellazioni di precisione (1952-1985)

Recent tectonic movements in North-Eastern Italy by a time series of precision levelings (1952-1985)

Abstract

A time series of precision levellings along the line Venice-Cortina, measured in the period 1952-1985, have been analyzed. The differences of heights between pairs of marks within a same bench mark have been distributed in order to estimate the errors in a single measuring step. The error of a difference of heights between distant bench marks has been obtained by propagation of previous errors considered as independent. All the heights have been referred to a bench mark in Treviso, which was measured in all levellings. Treviso has been chosen because it is rather close to the Adriatic Sea and because its lithological ground prevents short trend movements as due to anthropogenic subsidence. The time evolution of each bench mark referred to Treviso has been considered as linear. Within the quoted errors this linear fit is consistent everywhere except near Venice where anthropogenic subsidence occurred before 1970. The slope of a linear fit of the bench mark evolution versus distances is consistent with no movement from Preganziol (Venice) to Spresiano, and with a rotational movement increasing the height of the Alps around a fault, running NE-SW, passing through Spresiano. The rotation is consistent with constant angular velocity; precisely 3.6E-02 mm/year/km.