1. Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers
- Author
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Thorwart, Martin, Dannowski, Anke, Grevemeyer, Ingo, Lange, Dietrich, Kopp, Heidrun, Petersen, Florian, Crawford, Wayne, Paul, Anne, The Alparray Working Group, Christian-Albrechts-Universität zu Kiel (CAU), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), LOBSTER project that is part of the German Priority Programme SPP2017 4D-MB, ANR-15-CE31-0015,AlpArray-FR,Voir et comprendre les Alpes en 3D, de la croûte au manteau(2015), Institut de Physique du Globe de Paris (IPGP), and Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
- Subjects
010504 meteorology & atmospheric sciences ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,Stratigraphy ,Inversion (geology) ,Soil Science ,Induced seismicity ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,Geochemistry and Petrology ,Thrust fault ,14. Life underwater ,Compression (geology) ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Earth-Surface Processes ,[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics ,QE1-996.5 ,Rift ,Continental crust ,Paleontology ,Crust ,Geology ,QE640-699 ,Geophysics ,Seismology - Abstract
The northern margin of the Ligurian Basin shows notable seismicity at the Alpine front, including frequent magnitude 4 events. Seismicity decreases offshore towards the Basin centre and Corsica, revealing a diffuse distribution of low-magnitude earthquakes. We analyse data of the amphibious AlpArray seismic network with focus on the offshore component, the AlpArray ocean bottom seismometer (OBS) network, consisting of 24 broadband OBSs deployed for 8 months, to reveal the seismicity and depth distribution of micro-earthquakes beneath the Ligurian Sea. Two clusters occurred between ∼ 10 km to ∼ 16 km depth below the sea surface, within the lower crust and uppermost mantle. Thrust faulting focal mechanisms indicate compression and an inversion of the Ligurian Basin, which is an abandoned Oligocene–Miocene rift basin. The basin inversion is suggested to be related to the Africa–Europe plate convergence. The locations and focal mechanisms of seismicity suggest reactivation of pre-existing rift-related structures. Slightly different striking directions of presumed rift-related faults in the basin centre compared to faults further east and hence away from the rift basin may reflect the counter-clockwise rotation of the Corsica–Sardinia block. High mantle S-wave velocities and a low Vp/Vs ratio support the hypothesis of strengthening of crust and uppermost mantle during the Oligocene–Miocene rifting-related extension and thinning of continental crust.
- Published
- 2021