An upper bound on the rate of strain in the Central Apennines, Italy, from triangulation measurements between 1869 and 1963

Italy is covered by a first-order triangulation network that was established between 1869 and 1908 and re-measured in patches between 1936 and 1963. We analyse the measurements made in the central part of Italy to form an estimate of the rate of strain in the Central Apennines. We conclude that the rate of strain in this region is too small to detect from the repeated triangulation measurement. This result places an upper bound of about 10(exp-7)/yr on the strain rate of the Central Apennines, and implies that the maximum rate of extension across the region is no higher than about 3 mm/yr.