On May 24, the CNRS published a press release presenting the results of a study into the origin of earthquakes detected in the Lacq region.
Every year since 1969, numerous earthquakes of anthropogenic origin have been detected in the Lacq region of the Pyrénées-Atlantiques, without the exact cause being clearly identified. An international study led by Jean Letort, a teacher-researcher at Toulouse III – Paul Sabatier University and member of the Institut de recherche en astrophysique et planétologie (IRAP/OMP – CNES/CNRS/UT3), confirms a recent hypothesis. Industrial wastewater injections are at the root of the region’s seismicity.
The results were published on May 23 in Geophysical Journal International.
Read more
Read the article published in the Epos-France newsletter N°2, page 12
(a) Recent seismicity (2019-2023) in southern France, extracted from the French national BCSF-RENASS catalog. Events are labelled
as quarry blasts (red circles), natural earthquakes (blue circles) or induced or triggered earthquakes (green circles). The seismicity of Lacq (delimited by the black rectangle) is clearly separated from the seismicity linked to the Pyrenean chain. (b) Schematic cross-section of the Lacq anticline structure showing the position of the shallow oil reservoir (dark green area) and the deep gas reservoir (red area). The thick vertical bars (purple) represent the location of the injection wells (the main injection takes place just below the deep gas reservoir at 4.5 km). The black dots represent all the well-located induced earthquakes in this study, from 1975 to 2023, to within 2 km. Figure 1 from article Jacquemond et al. 2024