The 1564, Maritime Alps earthquake was investigated in the frame of the RHISE project: Moroni and Stucchi (1993) reconsidered the classical sources of the earthquake and investigated unpublished sources for Piemonte; Lambert (1993) investigated the Nice area and the Provence, while Rivara and Vaccari (1993) investigated the Ligurian area.

The picture of the earthquake is not very clear, yet (Tab. 1). Some sources, apparently independent, confirm that an earthquake happened on 1564, July 20; it damaged some towns of the Vesubie valley, was felt in Piemonte, probably at Borgo S. Dalmazzo (Grasso Dalmazzo, 1570) and could be felt as far as Aix-en-Provence (Sobolis, 1562-1607).

However, chronological problems are not completely solved. In particular, de Salicis (XVI) reports damage occurred on May 5 only at S. Jacques (La Bolline), not reported explicitely by other sources, and La Roche, also reported by Mogiol (1564). The wording used by de Salicis suggests the possibility that a big landslide occurred in May 1564 in the Valdeblore area, without relation to earthquakes.

According to most sources, the July 20 earthquake certainly produced landslides, which probably took place during a number of days or weeks, as it is normal in general and especially for this area (Perriaux, 1927). Therefore, it might be that reporters, such as Mogiol (1564), amalgamated descriptions related to various natural events as the result of a single "terremoto".

The same explanation may also apply for Lubonis (1565?), who writes almost one year after the earthquake and might amalgamate earthquake reports from the Vesubie valley with reports from the Roya valley, where damage reported at La Piene and Ventimiglia is not confirmed by archive investigation (Rivara and Vaccari, 1993). On the contrary, the result of this investigation suggests that Ventimiglia was flooded before the earthquake (Spring 1564) and La Piene after (Autumn 1564).

Following these points, damage reported from S. Jacques, La Roche, La piene and Ventimiglia will not be considered here as produced by the earthquake; for these localities intensity will not be assessed.