Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers

<p>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...

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Autores principales:	M. Thorwart, A. Dannowski, I. Grevemeyer, D. Lange, H. Kopp, F. Petersen, W. C. Crawford, A. Paul
Formato:	article
Lenguaje:	EN
Publicado:	Copernicus Publications 2021
Materias:	Geology QE1-996.5 Stratigraphy QE640-699
Acceso en línea:	https://doaj.org/article/56fcee84dbd04080b9d555a95e494196
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spelling	oai:doaj.org-article:56fcee84dbd04080b9d555a95e4941962021-11-12T05:27:19ZBasin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers10.5194/se-12-2553-20211869-95101869-9529https://doaj.org/article/56fcee84dbd04080b9d555a95e4941962021-11-01T00:00:00Zhttps://se.copernicus.org/articles/12/2553/2021/se-12-2553-2021.pdfhttps://doaj.org/toc/1869-9510https://doaj.org/toc/1869-9529<p>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.</p> <p>Two clusters occurred between <span class="inline-formula">∼</span> 10 km to <span class="inline-formula">∼</span> 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 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext>Vp</mtext><mo>/</mo><mtext>Vs</mtext></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="e2987b21cb5fcde70dac84e76b4bf118"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="se-12-2553-2021-ie00001.svg" width="34pt" height="14pt" src="se-12-2553-2021-ie00001.png"/></svg:svg></span></span> ratio support the hypothesis of strengthening of crust and uppermost mantle during the Oligocene–Miocene rifting-related extension and thinning of continental crust.</p>M. ThorwartA. DannowskiI. GrevemeyerD. LangeH. KoppH. KoppF. PetersenW. C. CrawfordA. PaulCopernicus PublicationsarticleGeologyQE1-996.5StratigraphyQE640-699ENSolid Earth, Vol 12, Pp 2553-2571 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Geology QE1-996.5 Stratigraphy QE640-699
spellingShingle	Geology QE1-996.5 Stratigraphy QE640-699 M. Thorwart A. Dannowski I. Grevemeyer D. Lange H. Kopp H. Kopp F. Petersen W. C. Crawford A. Paul Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers
description	<p>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.</p> <p>Two clusters occurred between <span class="inline-formula">∼</span> 10 km to <span class="inline-formula">∼</span> 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 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext>Vp</mtext><mo>/</mo><mtext>Vs</mtext></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="e2987b21cb5fcde70dac84e76b4bf118"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="se-12-2553-2021-ie00001.svg" width="34pt" height="14pt" src="se-12-2553-2021-ie00001.png"/></svg:svg></span></span> ratio support the hypothesis of strengthening of crust and uppermost mantle during the Oligocene–Miocene rifting-related extension and thinning of continental crust.</p>
format	article
author	M. Thorwart A. Dannowski I. Grevemeyer D. Lange H. Kopp H. Kopp F. Petersen W. C. Crawford A. Paul
author_facet	M. Thorwart A. Dannowski I. Grevemeyer D. Lange H. Kopp H. Kopp F. Petersen W. C. Crawford A. Paul
author_sort	M. Thorwart
title	Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers
title_short	Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers
title_full	Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers
title_fullStr	Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers
title_full_unstemmed	Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers
title_sort	basin inversion: reactivated rift structures in the central ligurian sea revealed using ocean bottom seismometers
publisher	Copernicus Publications
publishDate	2021
url	https://doaj.org/article/56fcee84dbd04080b9d555a95e494196
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Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers

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