Impacts of Water and Stress Transfers from Ground Surface on the Shallow Earthquake of 11 November 2019 at Le Teil (France)

André Burnol (1) , Antoine Armandine Les Landes (1) , Daniel Raucoules (1) , Michael Foumelis (2, 1) , Cécile Allanic (1) , Fabien Paquet (1) , Julie Maury (1) , Hideo Aochi (1) , Théophile Guillon (1) , Mickael Delatre (1) , Pascal Dominique (1) , Adnand Bitri (1) , Simon Lopez (1) , Philippe Pébaÿ (3) , Behrooz Bazargan-Sabet (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 Aristotle University of Thessaloniki
3 NGA - NexGen Analytics

The 4.9 Mw earthquake of 11 November 2019 at Le Teil (France) occurred at a very shallow depth (about 1 km), inducing the surface rupture of La Rouvière fault. The question was raised shortly after about the potential impact of a nearby surface quarry. Thanks to satellite differential interferometry, here, we revealed the existence of a secondary surface rupture of the quasi-parallel Bayne Rocherenard fault. A newly processed seismic cross-section allowed us to shape the three-dimensional geometry of the local three-fault system. Assuming that the earthquake was triggered by the impact of meteoric water recharge, our numerical simulations show that the hydraulic pressure gradient at depth was at a maximum during the period of 2010–2019, just before the seismic event. The estimated overpressure at the intersection of the two faults, which is the most probable place of the hypocenter, was close to 1 MPa. This hydraulic effect is about two and a half times larger than the cumulative effect of mechanical stress release due to the mass removal from the surface quarry over the two past centuries. This work suggests a rapid hydraulic triggering mechanism on a network of faults at a shallow depth after a heavy rainfall episode.

Mots clés: Le Teil earthquake; surface rupture; shallow seismicity; hydro-seismicity; rainfall; stress transfer; quarry; ComPASS; 3DEC

Domaines: Planète et Univers [physics]

André Burnol, Antoine Armandine Les Landes, Daniel Raucoules, Michael Foumelis, Cécile Allanic, et al.. Impacts of Water and Stress Transfers from Ground Surface on the Shallow Earthquake of 11 November 2019 at Le Teil (France). Remote Sensing, 2023, Role of Remote Sensing in Investigating Fault Zone Properties over Various Spatial-Temporal Scales, 15 (9), pp.2270. ⟨10.3390/rs15092270⟩. ⟨hal-04086025⟩