EGU24-14660, updated on 09 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

High-resolution seismic imaging of the sub-bottom Quaternary deposits revealed an active fault in the Vinodol-Velebit channel (Kvarner, Croatia)

Tvrtko Korbar1, Ozren Hasan1, Dea Brunović1, and Snježana Markušić2
Tvrtko Korbar et al.
  • 1Croatian Geological Survey, Zagreb, Croatia (
  • 2Faculty of Science, Department of Geophysics, University of Zagreb, Zagreb, Croatia (

Kvarner area belongs to the External Dinarides fold-and-thrust belt that is characterized by intensive tectonic deformations of a few kilometers thick sedimentary cover of the central part of the Adriatic microplate. The main deformations occurred predominantly during Eocene to Oligocene thin-skinned tectonics, while late-orogenic thick-skinned deformations and wrenching resulted in the exhumation of the orogenic belt. The latter tectonic mechanism is supposed to be still active, but there is no reported evidence of active faults on the surface of predominantly karstic terrain. Nevertheless, seismological data reveal subsurface activity along various fault plane solutions, and crucial evidence of possible active deformations on the surface is expected within stratified superficial deposits in the area. However, stratified Quaternary sediments are rare onshore and on the Kvarner islands but are widespread on the bottom of the surrounding Adriatic Sea. During the targeted high-resolution sub-bottom geoacoustic seismic survey we focused on the zones that are characterized by earthquakes and on the previously arbitrarily recognized regional seismogenic sources. However, only shallow seismic profiles along and across the Vinodol and the NW part of the Velebit channel revealed clear evidence of fault-related deformations of the youngest Quaternary sediments. The fault zone is up to hundreds of meters wide, limited by parallel sub-vertical fault planes, and characterized by deformations of the strata between the planes either in a positive (uplifted) or a negative (downthrown) manner along the strike, which are typical for strike-slip faults. Besides, the disturbed layering of the uppermost well-stratified unit (Late Pleistocene) resembles fluid/sediment escape structures that could be related to strong shaking during prehistorical earthquakes. The fault zone is also tentatively recognized in the onshore bedrock along the strike of the submerged fault, where it appears as an indistinct fractured zone that is more corroded than surrounding bedrock carbonates. Therefore, sub-bottom profiling has been proven to be a useful tool for identifying active faults and should be used as a key method in future seismotectonic research of submerged seismogenic zones.

How to cite: Korbar, T., Hasan, O., Brunović, D., and Markušić, S.: High-resolution seismic imaging of the sub-bottom Quaternary deposits revealed an active fault in the Vinodol-Velebit channel (Kvarner, Croatia), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14660,, 2024.

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supplementary materials version 1 – uploaded on 16 Apr 2024
  • AC1: Comment on EGU24-14660, Tvrtko Korbar, 16 Apr 2024

    Dear colleagues,

    you are welcome to post comments, especially on the origin on high amplitude reflections (liquefaction or fluidized sediment escape structures/flow?)  and possible type of tectonic movement of the basement rocks according to the interpreted seismic images across the superficial sediments.

    Thank you in advance.

    Tvrtko Korbar