Fault activity along the western margin of the Argos Gulf (Peloponnese, Greece) revealed by tectonic geomorphology analysis

The Gulf of Argos, Greece, is a post-Miocene basin at the north-western extremity of the Cretan Sea (southern Aegean). Its formation is attributed to NE-SW-oriented back-arc extension, induced by rollback of the subducting slab in the Hellenic arc.

The western margin of the Gulf of Argos is marked by the almost linear coastline of the eastern Peloponnese, and is related to a c.100 km long, NNW-SSE normal fault system, stretching from Kiveri to Ariana. Despite it being a recognizable structure, there are few, if any, constraints related to its degree of activity, possible segmentation, and seismic hazard potential. The immediate footwall to this fault system, which we name Western Argos Fault System (WAFS), hosts several similarly striking high-angle normal faults, whose Quaternary degree of activity is also poorly understood.

To better understand fault activity and evolution in the Gulf of Argos, we study the mid- to long-term (several kyr to a few Myr) development of the footwall of the West Argos Fault System. Our study focuses on how drainage river long profiles and footwall relief have responded dynamically to tectonic activity. We estimate an uplift rate for each footwall catchment along the WAFS from knickpoint analysis and estimates of bedrock erodibility. We then compare these results with vertical motion data collected in the field and topographical data along the western margin of the Gulf of Argos.

We propose a throw rate of 0.9-2.4 mm/yr along the WAFS, which comprises at least four segments and an overall southward migration of fault activity, as the northernmost segments appear to be significantly less active than the southern ones.