Source inversion of the 1570 Ferrara earthquake and definitive diversion of the Po River (Italy)

摘要

An 11-parameter, kinematic-function (KF) model was used to retrieve the approximate geometrical and kinematic characteristics of the fault source of the 1570 M-w 5.8 Ferrara earthquake in the Po Plain, including the double-couple orientation (strike angle 12716 degrees, dip 287 degrees, and rake 7716 degrees). These results are compatible with either the outermost thrust fronts of the northern Apennines, which are buried beneath the Po Plain's alluvial deposits, or the blind crustal-scale thrust. The 1570 event developed to the ENE of the two main shocks on 20 May 2012 (M 6.1) and 29 May 2012 (M 5.9). The three earthquakes had similar kinematics and are found 20-30km from each other en echelon in the buried chain. Geomorphological and historical evidence exist which suggest the following: (i) the long-lasting uplift of the buried Apenninic front shifted the central part of the course of the Po River approximately 20km northward in historical times and (ii) the 1570 earthquake marked the definitive diversion of the final part of the Po River away from Ferrara and the closure of the Po delta 40km south of its present position.