In troubled times, in a divided country: the Upper Tiber Valley earthquake of 1789.

Abstract

Our perception of the September 30, 1789 earthquake (Io = VIII-IX MCS, M = 5.8 according to the latest Italian catalogue) is blurred by two major disturbance factors: it occurred across a political frontier and at a time of high political unrest. Its having been experienced by two independent countries (the Grand-Duchy of Tuscany and the Papal States) means that the 1789 earthquake provoked two independent official responses, embodied in a huge mass of records (letters, forms and reports concerning enquiries, damage surveys, relief measures, financial accounts et cetera), afterwards destined to be stored in different ways and places and therefrom to undergo intricate vicissitudes that led, in some cases, to their final or temporary loss. Its having occurred in the autumn of 1789, means that this earthquake did not attract as much interest, from the media and the scientific world, as it would probably have got had it happened in less troubled times. The Bastille had been stormed, the Declaration of the Rights of Men had been issued and Europe was still reeling under the shock. In Italy, professional journalists and cultured dilettanti alike were either too enthused or too outraged by the French goings on and their repercussions on international politics, to devote more than a perfunctory attention to an inland earthquake whose highest effects affected country villages and provincial towns in a secluded corner at the heart of the peninsula. Consequently, the 1789 earthquake rated only a few mentions in contemporary Italian gazettes, and none of the scientifically-minded took time to write treatises on its subject. Digging up the details of what actually happened in the Upper Tiber valley on September 30, 1789 earthquake is therefore far from easy, especially as parts of the original puzzle are probably lost for good. However, is it still worthwhile to spend time looking for them as the findings of a careful search allows to considerably improve the picture of this earthquake, as the necessary preliminary to a re-assessment of its epicentral parameters.