Crawford, Wayne

Dannowski, Anke

Kopp, Heidrun

Lange, Dietrich

Paul, Anne

Thowart, Martin

Wolf, Felix

OceanRep

Geophysical Research AbstractsVol. 20, EGU2018-15896, 2018EGU General Assembly 2018© Author(s) 2018. CC Attribution 4.0 license.AlpArray offshore: Preliminary results of the Ligurian Sea OBS networkand refraction linesHeidrun Kopp (1,4), Wayne Crawford (2), Anne Paul (3), Dietrich Lange (1), Anke Dannowski (1), Felix Wolf(1), and Martin Thowart (4)(1) GEOMAR, Kiel, Germany, (2) Institut de Physique du Globe de Paris, France, (3) Institut des Sciences de la Terre(ISTerre) CNRS & Université Grenoble Alpes, France, (4) University of Kiel, GermanyThe north-eastern portion of the Ligurian Sea forms part of the transition zone from the Alpine orogeny to theApennine orogeny. North of the Ligurian Sea, the Alpine slab subsides beneath the Alpine belt whereas to thesoutheast, the Adriatic plate subsides underneath the Apennine belt. The entire area is in the focus of the AlpArrayinitiative to provide state-of-the-art imaging of subsurface structures. The offshore component of AlpArray in-volves the deployment of 30 broadband ocean bottom seismometers (OBS) from France/Germany in the LigurianSea for a period of eight months. The network extends the dense seismometer network of the AlpArray initiativethat covers the entire region of the Alps onshore. OBS recordings of teleseismic events will be essential to definesubsurface structures at the transition from the Western Alps to the Apennines and improve our understanding ofthe 3D-geometry of the system and its kinematics. OBS deployment took place in June 2017 using the French RVPourquoiPas? as platform. In order to share ship-related costs between the two nations, recovery is conducted usingRV Maria S. Merian in Feburary 2018. Here we present early results of the OBS long-term recordings as well asfrom an amphibious seismic refraction survey of the Ligurian basin covering the transition from the oceanic to thecontinental domain. Two active shoreline crossing wide-angle transects of 150 nm each unravel the upper structureof the Ligurian Basin at crustal scale resolution. A particular focus of the study is on the ocean-continent boundaryat the Alps-Apennines junction, which is poorly defined due to the lack of modern refraction data. The Ligurianbasin is a back-arc basin, created by the subduction roll-back of the Apennines-Calabria-Maghrebides subductionzone towards southwest. Caused by the roll back of the trench the continental crust was stretched and thinned anda back-arc spreading centre was created that produced new oceanic crust. Hypotheses about the evolution of theLigurian basin are based on older geophysical and seismic data sets with limited resolution and depth penetration.The two newly acquired refraction seismic refraction lines, with short instrument spacing of 8 km and short shotinterval of 50 s, will help to estimate the structure, nature, and the thickness of the crust and overlying sedments inorder to consolidate existing theories. Furthermore, with the integration of the marine stations into the AlpArrayseismic network, seismic traveltime tomographic approaches will be improved. Based on the acquired data, newinsights on the location of the subducting slabs in the transition zone between the Alps and the Apennines will begained and questions on the 3D-geometry of the subduction polarity reversal might be answered.

AlpArray offshore: Preliminary results of the Ligurian Sea OBS network and refraction lines

http://oceanrep.geomar.de/42747/1/EGU2018-15896.pdf

AlpArray offshore: Preliminary results of the Ligurian Sea OBS network and refraction lines

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