KAROS: Investigation of the Kefalonia Transform Fault Zone using seismic wavefield analyses: seismicity, Amphibious array measurements, local gradients, and ROtationS

DEFORM

KAROS: Investigation of the Kefalonia Transform Fault Zone using seismic wavefield analyses: seismicity, Amphibious array measurements, local gradients, and ROtationS

This project aims at gaining new insights and improving our knowledge about the crustal deformation and structural properties of the Kefalonia Transform Fault Zone (KTFZ). The KTFZ is one of the most active faults in Europe. Examples of recent destructive earthquakes are the Mw 7.0 1953 and the Mw 6.8 1983 events. The KTFZ is supposed to represent a STEP fault at the transition from oceanic subduction in the south to continental collision in the north. Details of the fault geometry, its segmentation as well as the edge of the Ionian slab below remain to be resolved. KAROS will focus on fault scale processes (DEFORM research theme 2: seismic and aseismic behaviour of faults as well as characterization of plate boundaries and their deformation) using new methodologies for detailed seismicity and focal mechanism characterization. Innovative approaches to 3D seismic tomography and stress field characterization will provide the link to plate scale processes (DEFORM research theme 1: geodynamic drivers and plate configuration). Finally, the results of our amphibious experiments will provide important ingredients for physical earthquake and tsunami hazard assessment (DEFORM research theme 3). For the first time, the KTFZ is investigated by an amphibious passive seismic experiment involving 15 ocean bottom stations to the West / South-West of the KTFZ as well as 10 6- component stations and small scale arrays on Kefalonia and Lefkada Islands. Implementing novel methodologies arising from the possibility of directly observing spatial wavefield gradients, we will systematically characterize the fault structure as well as the edge of the underlying oceanic slab. Connecting direct and array derived wavefield gradient observations with Eikonal and Helmholtz tomography will allow us to significantly improve our knowledge about the local shear-wave velocity structure as well as the upper mantle and crustal anisotropy. 6C observations combined with the improved spatial data coverage which we obtain by the OBS deployments as well as the continuation of the current AdriaArray deployments (DSEBRA) will reveal seismicity and focal mechanisms along the KTFZ in unprecedented details. Overall, our study will help to better understand geodynamic drivers of earthquake and tsunami hazard in this DEFORM key area.

October, 2025

September, 2028

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196000

DFG / Priority Programmes Subproject of SPP 2497

Ludwig-Maximilians-Universität München (LMU), Germany

Ingo Grevemeyer

Ludwig-Maximilians-Universität München (LMU), Germany
Penteli’s Astronomical Station, Greece
National and Kapodistrian University of Athens, Greece
University of Thessaloniki, Greece
University of Patras, Greece
Christian-Albrechts-Universität zu Kiel (CAU), Germany