The 14 August 1708 Manosque, France earthquake: new constraintson the damage area from in-depth historical studies

Abstract

In this paper, we re-evaluate the damage area of the 14 August 1708 Manosque earthquake, Southeast France. It is the strongest event (Io = VIII MSK) of a seismic sequence that lasted from March to October 1708. We show that the spatial repartition of the damage that can be proposed based on the existing sources, is clearly biased by the abundant narrative information concerning Manosque. This sparseness in the information can be attributed to differences in communication routes or strategies between the different localities, and affects the global perception of the event, especially in the rural area. To tackle this bias, we propose to inventory the building repairs reported in non-narrative sources in order to capture the effects of the Manosque earthquake in the surrounding region. The debates and accounts (between mid-1708 and 1710) show that moderate to heavy repairs consistently affect localities in the epicentral area, covering a region of at least 12 km radius around Manosque. These building repairs, indirectly attesting to earthquake damage, provide valuable and complementary information, which resulted in a better knowledge of this event. In particular, we propose new intensity estimates (I >VI) at six localities.