RECENT GEOMORPHIC CHANGES AND ANTHROPOGENIC ACTIVITIES IN THE DELTAIC PLAIN OF PINIOS RIVER IN CENTRAL GREECE

The Pinios river delta is a Late Holocene arcuate type delta, located in the southern Thermaikos gulf (Central Greece). In order to determine the processes which contributed in the recent configuration of the delta, a detailed geomorphic map at the scale of 1:5000 has been prepared showing both the deltaic plain and the coastal zone features using GIS techniques. Comparative examinations of aerial photographs taken in different dates and reliable maps of the last two centuries along with field observations depict recent changes of the delta morphology. The most important factors for the development of the delta are fluvial sedimentation, wave activity and longshore currents in a tectonically active area. Land uses throughout the delta plain have been mapped in an attempt to identify socio-economic activities. The dominant feature in the deltaic plain is the numerous abandoned meandering channels. The delta shoreline is generally retreating due to marine processes especially where former river mouths occur. Finally, various future sea-level rise scenarios have been analyzed and an assessment of the impacts of the potential global future sea-level rise to the delta is estimated

Late quaternary rates of stream incision in northeast Peloponnese, Greece

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Assessment of neotectonic landscape deformation in Evia Island, Greece, using GIS-based multi-criteria analysis

This study deals with the assessment and mapping of neotectonic landscape deformation in the northern part of the Evia Island (Central Greece). Multi-Criteria Decision Analysis (MCDA) utilizing Analytic Hierarchy Process (AHP) andWeighted Linear Combination (WLC) procedures were conducted for the calculation of the Neotectonic Landscape Deformation Index (NLDI). The study is based on the combination of morphotectonic, geomorphological and geological parameters. The GIS-based spatial MCDA led to the classification of the study area into five classes of neotectonic deformation (from very low to very high) and to a neotectonic deformation map. The results were compared with the outputs of a relative tectonic activity classification approach based on quantitative geomorphic analysis at a regional scale, including site-specific field observations. Areas of high and very high deformation are related to the major active faults of Dirfis, Kandili and Gregolimano- Telethrio. Other minor active normal faults of medium to high seismic risk level, affecting the northern and northeastern parts of the island, are also associated with areas of intense landscape neotectonic deformation

GEOMORPHOLOGY AND SEDIMENTOLOGICAL PROCESSES ALONG THE COASTAL ZONE BETWEEN LIVANATES AND AGIOS KONSTANTINOS (N. EVOIKOS GULF, CENTRAL GREECE)

This study deals with aspects of geomorphology and nearshore marine processes in the coastal zone located between Livanates and Agios Konstantinos (North Evoikos Gulf, central Greece). Evoikos Gulf is a tectonic graben bounded by WNW-ESE trending normal faults; it can be further characterized as semi-closed marine basin with water depths exceeding 400m.The Coastal geomorphology is affected by active tectonics with the most prominent morphological features being the uplifted marine terraces and the well-developed deltaic fan of Xerias torrent. In the present investigation, detailed geomorphological mapping at a scale of 1:5000 was performed together with granulometric analysis, while nearshore wave and current activity related to sediment dynamics has been determined on the basis of wind-generated wave regime. The examined coastal zone consists of a series of alluvial cones and fans, Xerias fan being the largest among them, low cliffs, a cuspate foreland and beach zones of limited length, often hosting beachrock formations. The formation and evolution of the study area seems to be controlled by the limited terrestrial influxes, the relatively weak wave regime due to limited wave fetches distances, and the associated longshore currents that induces limited sediment transport

The 2008 Methoni earthquake sequence: the relationship between the earthquake cycle on the subduction interface and coastal uplift in SW Greece

Seismological, GPS and historical data suggest that most of the 40 mm yr$^{-1}$ convergence at the Hellenic Subduction Zone is accommodated through aseismic creep, with earthquakes of $\textit{M}$W ≲ 7 rupturing isolated locked patches of the subduction interface. The size and location of these locked patches are poorly constrained despite their importance for assessment of seismic hazard. We present continuous GPS time-series covering the 2008 MW 6.9 Methoni earthquake, the largest earthquake on the subduction interface since 1960. Post-seismic displacements from this earthquake at onshore GPS sites are comparable in magnitude with the coseismic displacements; elastic-dislocation modelling shows that they are consistent with afterslip on the subduction interface, suggesting that much of this part of the interface is able to slip aseismically and is not locked and accumulating elastic strain. In the Hellenic and other subduction zones, the relationship between earthquakes on the subduction interface and observed long-term coastal uplift is poorly understood. We use cGPS-measured coseismic offsets and seismological body-waveform modelling to constrain centroid locations and depths for the 2008 Methoni $\textit{M}$W 6.9 and 2013 Crete $\textit{M}$W 6.5 earthquakes, showing that the subduction interface reaches the base of the seismogenic layer SW of the coast of Greece. These earthquakes caused subsidence of the coast in regions where the presence of Pliocene–Quaternary marine terraces indicates recent uplift, so we conclude that deformation associated with the earthquake cycle on the subduction interface is not the dominant control on vertical motions of the coastline. It is likely that minor uplift on a short length scale (∼15 km) occurs in the footwalls of normal faults. We suggest, however, that most of the observed Plio-Quaternary coastal uplift in SW Greece is the result of thickening of the overriding crust of the Aegean by reverse faulting or distributed shortening in the accretionary wedge, by underplating of sediment of the Mediterranean seafloor, or a combination of these mechanisms.AH is supported by a Shell Exploration studentship. This study forms part of the NERC- and ESRC-funded project “Earthquakes Without Frontiers” under grant NEJ02001X/1, and was partly funded by the NERC grant “Looking inside the Continents from Space”

Recognition of past earthquakes along the Sparta fault (Peloponnesus, southern Greece) during the Holocene, by combining results of different dating techniques

Sparta fault is an impressive landform, located on the eastern front of Taygetos mountain, southern Greece. Detailed morphotectonic observations on this fault suggest that it should be active at least since Early Quaternary. However, according to the current seismological knowledge, this region is characterized by very low seismicity. The only reported earthquake to have occurred in this area is that of 464 b. c., a destructive event that devastated the whole city of Sparta. In order to get information on the occurrence of past earthquakes during the Holocene, results of different independent dating works that have performed along the Sparta fault were used. These researchers confirm the existence not only of the 464 B.C. earthquake but also of several more that occurred at ca. 3900 b. c., 2500 B.C. and 2000 B.C., 550 A.D. and 1000 A.D. The events that occurred at 2500 and 464 B.C. should correspond to major events of magnitude of the order of 7, which ruptured the entire length of the fault, while these at 3900 B.C., 2000 B.C., 550 A.D. and 1000 A.D., to smaller events of magnitude 6-6.5. The return periods of strong earthquakes along the Sparta fault is estimated to be around 2000 years, but within these periods events of smaller magnitude that ruptured segments of the fault have also occurred. © 2005 Elsevier Ltd. All rights reserved