The central Ionian Islands of western Greece are among the most seismically active regions in the Mediterranean Sea. Deformation is largely accommodated by the Kefalonia Transform Fault (KTF), which is a major right-lateral strike-slip fault that links the Apulian collision zone to the Hellenic subduction margin. The KTF has generated numerous moderate to large earthquakes and poses strong ground shaking and tsunami hazards.
Despite its importance, the precise location and activity rates of the fault remain poorly understood, as areas near the shore, where fault traces are expected, have not been extensively studied (water depth of less than 125 m). This portion of the shallow seabed is crucial for understanding the geomorphic evolution of active submarine faults, as eustatic cycles alternately expose it to submarine and subaerial erosion. This gradient of processes subjects fault scarps to varying rates of reworking, which could potentially reveal their activity over different timescales. Furthermore, it is reasonable to assume that if an active fault determines the extent of uplifted land, then its location is likely to be submerged beneath the current high sea level, as recent studies in Japan suggest.
The aim of this project is to bridge the gap between offshore and onshore tectonic observations by producing high-resolution bathymetric maps of the shallow nearshore zone along the KTF. To this end, a low-cost uncrewed surface vessel (USV) equipped with multibeam sonar will be developed, calibrated and deployed to survey key segments of the fault zone and potential drowned marine terraces. These offshore data will complement ongoing terrestrial studies of the KTF’s tectonic history.
The expected outcomes are an improved inventory of active faults, with more accurate information about their geometry and slip rates. There will also be a demonstration of the effectiveness of low-cost, unmanned surface vehicle (USV)-based surveys for investigating near-shore seismogenic faults.
Start/end dates: September 2025 – September 2028 (3 years).
Funding: Internal funding.
Section researchers involved: Ambrosio Vega-Ruiz & Dr. Luca Malatesta
Cooperations:
Dr. Pierre Dietrich, University of Rennes, France.
Dr. Silvia Crosseto, Section 4.1 ‘Lithosphere Dynamics’, GFZ Helmholtz Centre for Geosciences.
Marcel Ludwig, Section 1.1 ‘Space Geodetic Techniques’, GFZ Helmholtz Centre for Geosciences.