Searching for the Source of the 1117 Earthquake in Northern Italy: A Multidisciplinary Approach

Although the occurrence of the Jan. 3, 1117 earthquake had a vast echo throughout Europe in contemporaneous chronicles, available historical sources do not permit to detail the effects, and generic evidence of damage in Italy may only be related to Verona, Ronco all’Adige, Costozza, Padova, Cremona and Nonantola. Recent seismic catalogues locate the epicentre of the earthquake in the Verona area and define a magnitude M=6.5. In order to improve the knowledge on the effects of the 1117 earthquake, an attempt has been made to merge information derived from different approaches (architectural history, archaeology and historical geology). Gathered data indicate that an area including the towns of Padova, Verona and Trento may have been strongly affected by the earthquake. However, due to incompleteness and uncertainty of the data, the obtained picture has to be considered as a partial view of the area which experienced significant damage and geological effects related to the 1117 event. The active faults (Mt. Baldo and Lessini Mts.) in the defined area have been investigated by means of paleoseismological techniques. Paleoseismological data indicate that no surficial displacements due to the 1117 earthquake may be related to the investigated faults. These data point out that the seismogenic structure which was responsible for the earthquake (together with the earthquake epicentre) is probably located outside the area of possible damage defined by means of the above mentioned integrated approach. The most valid hypothesis is that the earthquake originated east of the Verona area, along the active south-verging thrust systems (responsible for strong historical earthquakes) which border the Venetian Plain to the north.