A comparative study of neotectonic basins across the Hellenic arc: the Messiniakos, Argolikos, Saronikos and Southern Evoikos Gulfs

Abstract

Detailed single-channel continuous seismic reflection profiling data from four gulfs as well as onshore neotectonic investigations have allowed the study of the neotectonic structure of the Hellenic arc along a complete transverse section from its external area in the trench to the internal back-arc area.It is the direct continuation of the continental slope from the trench to the island arc (Peloponnesus, Crete, Dodekannese). Argolikos Gulf is an almost symmetric NW-SE graben occupying the northern edge of the Cretan back-arc basin. Saronikos Gulf is a multi-complex structure of a NW-SE graben in the SW (Epidaurus Basin) and alternation of E-W horsts and grabens in the North. Its neotectonic evolution is characterized by the Plio-Quaternary volcanic arc activity. Southern Evoikos Gulf is a relatively shallow neotectonic graben in the back-arc area at the northern prolongation of the Cycladic Platform.Each of the above neotectonic basins has its own characteristics which are probably due to their geodynamic position in the Hellenic arc. In general, there is a decrease in the neotectonic deformation, the sediment thickness and the sedimentation rates from SW to NE, going from the periphery to the core of the arc.Messiniakos Gulf is an asymmetric NW-SE structure with considerable tilt towards the NE.

Geological, Geomorphological and Tectonic Structure of Ne Attica and Seismic Hazard Implications for the Northern Edge of the Athens Plain

“…The southern Evoikos gulf is a shallow basin less than 250 m deep that separates Attica from the southern Evia and was formed in Late Pliocene. The thickness of the Plio-Quaternary sediments within the gulf does not exceed 150 m, except for the southeastern area, where they are 250 m thick (Papanikolaou et al 1988a). Marine sediments occur only along the coast of eastern Attica at Rafina area where they have been dated as uppermost Pliocene -lower Pleistocene (Mitzopoulos 1948, Guernet andSauvage 1970).…”

“…The E-W trending faults are large and known to generate medium to large magnitude earthquakes (1938( Oropos M=6.0, 1981 Alkyonides earthquake sequence M=6.7, M=6.4, M=6.3, 1999 Athens M=5.9), whereas the NW-SE faults occurring in the east are shorter, have lower rates and produce low to medium magnitude earthquakes (Papanikolaou and Lozios 1990). This neotectonic pattern has been analysed in the northern Attica through morphotectonic observations (Papanikolaou et al 1988b), as well as offshore studies in the Saronikos and the southern Evoikos gulfs (Papanikolaou et al 1988a). …”

Major Paleogeographic, Tectonic and Geodynamic Changes From the Last Stage of the Hellenides to the Actual Hellenic Arc and Trench System

“…This alternation of neotectonic horsts and grabens in the NNW-SSE direction shows a WSW-ENE directed extension that forms arc-parallel structures within the Aegean upper plate. The intensity of deformation as expressed by the topographic relief, the sedimentary thickness and the fault displacement values shows a decrease from the external part of the arc in the southwest towards the internal part in the northeast (Papanikolaou et al, 1988). The minimum extension estimated across the above profile is 35 km, considering a mean 45 o dip of the normal faults forming the marginal faults of the basins.…”

“…Schematic neotectonic map and profile across the arc parallel basins/grabens of the Southern Hellenides, developed within Late Miocene -Present under an extension in the ENE-WSW direction (modified after Papanikolaou et al, 1988). A decrease of the deformation is shown by the estimated magnitude of fault throw along the profile.…”

Offshore Faulting in the Aegean Sea: A Synthesis Based on Bathymetric and Seismic Profiling Data

“…Perissoratis and Papadopoulos (1999) defined the major faults of the area from Argolic Gulf, on the west, over the southern Cyclades Archipelago to the Island of Kos on the East. Papanikolaou et al (1988) traced the faults of Saronic, Argolic and South Evia Gulfs. Piper and Perissoratis (2003) provided a synthetic map of both, new and previously known, offshore faults in the South Aegean Sea.…”