The 1909 Lambesc earthquake @ PATA Days 2022

On the 11th June, 1909 a moderate earthquake (Mw 6.0) hit the Provance region, with an epicenter located somewhere between Rognes and Saint-Cannat.

The shaking was locally very strong and damages were widespread in the Villages of Roignes, Lambesc and others, with waves felt as far as hubdreeds of kilometers.

Incredibly, studies on the inversion of the few seismographs available, agree in locating the source at only 1 km of depth with an inverse kinematics! The most plusible culprit is one of the thrust belonging to the Trevaresse Fault System, presently under investigation by the Université Aix-Marseille research group, among others.

During the PATA Days 2022 we had the opportunity to visit the epicentral area of the 1909 earthquake, listen to the records of those days, read by the representative of a local association, in charge of keeping the memory of the eathquake alive.

We also investigated two sites where the possible emergence of this apparently blind thrust faulting could appear. Our field trip was lead by Prof. Magali Rizza, who guided us at the search of very subtle evidence of surface faulting.

One site has already given good results, based on a paper by Chardon et al. (2005) that trenched the fault splay responsible for the 1909 earthquake.

Nonetheless, more research is needed, especially in the western sector of the Trevaresse Fault, where a trench is planned for the near future. Finger crossed!