Basin inversion: Reactivated rift structures in the Ligurian Sea revealed by OBS.

Thorwart, Martin, Dannowski, Anke , Grevemeyer, Ingo , Lange, Dietrich , Kopp, Heidrun , Petersen, Florian , Crawford, Wayne and Paul, Anne and AlpArray Working Group (Submitted) Basin inversion: Reactivated rift structures in the Ligurian Sea revealed by OBS. Open Access Solid Earth . DOI 10.5194/se-2021-9.

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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 OBS network, consisting of 24 broadband ocean bottom seismometers deployed for eight 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 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 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 structures. Slightly different striking directions of faults in the basin centre compared to faults further east and hence away from the abandoned rift may mimic the counter-clockwise rotation of the Corsica-Sardinia block during ~20–16 Ma. The observed cluster events support the hypothesis of strengthening of crust and uppermost mantle during rifting related extension and thinning of continental crust.

Document Type: Article
Keywords: Ligurian Sea, seismicity, focal mechanisms, rifting, basin inversion, ocean bottom seismometer, OBS, AlpArray
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Kiel University
Main POF Topic: PT3: Restless Earth
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/se-2021-9
ISSN: 1869-9529
Related URLs:
Projects: AlpArray, LOBSTER
Expeditions/Models/Experiments:
Date Deposited: 08 Feb 2021 10:13
Last Modified: 04 Mar 2021 13:00
URI: http://oceanrep.geomar.de/id/eprint/51739

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