Publications by Year: 2013

Alexopoulos J, Vassilakis E, Dilalos S, Pantelis C, Papadopoulos T. Identification of buried active structures with preliminary geophysical and morphotectonic analysis, at eastern Thessaly basin, Greece. In: 4th International INQUA Meeting on Paleoseismology, Active Tectonics and Archeoseismology (PATA). Aachen; 2013. pp. 1-4. pdf
Alexopoulos J, Vassilakis E, Dilalos S, Zaloumi E. Quantification of anthropogenic impact on natural evolution processes at a coastal zone, adjacent to an active fault. In: 13th International Conference on Environmental Science and Technology. Athens; 2013. pdf
Bradley K, Vassilakis E, Weiss B, Royden L. A re-assessment of the shallow paleomagnetic inclinations of the western Cyclades, Greece. Bulletin of the Geological Society of Greece [Internet]. 2013;XLVII (2):498-507. pdf
Vassilakis E, Papadopoulou-Vrynioti K. The tectonic control of an underground river, Agia Triada Cave (Karystos, Greece). In: 16th International Congress of Speleology. Czech; 2013. pp. 208-213. pdf
Papanikolaοu ID, Roberts GP, Deligiannakis G, Sakellariou A, Vassilakis E. The Sparta Fault, Southern Greece: From segmentation and tectonic geomorphology to seismic hazard mapping and time dependent probabilities. Tectonophysics [Internet]. 2013;597–598:85 - 105.
The Sparta Fault system is a major structure approximately 64 km long that bounds the eastern flank of the Taygetos Mountain front (2407 m) and shapes the present-day Sparta basin. It was activated in 464 B.C., devastating the city of Sparta. This fault is examined and described in terms of its geometry, segmentation, drainage pattern and post-glacial throw, emphasising how these parameters vary along strike. Qualitative analysis of long profile catchments shows a significant difference in longitudinal convexity between the central and both the south and north parts of the fault system, leading to the conclusion of varying uplift rate along strike. Catchments are sensitive in differential uplift as it is observed by the calculated differences of the steepness index ksn between the outer (ksn < 83) and central parts (121 < ksn < 138) of the Sparta Fault along strike the fault system. Based on fault throw-rates and the bedrock geology a seismic hazard map has been constructed that extracts a locality specific long-term earthquake recurrence record. Based on this map the town of Sparta would experience a destructive event similar to that in 464 B.C. approximately every 1792 ± 458 years. Since no other major earthquake M ~ 7.0 has been generated by this system since 464 B.C., a future event could be imminent. As a result, not only time-independent but also time-dependent probabilities, which incorporate the concept of the seismic cycle, have been calculated for the town of Sparta, showing a considerably higher time-dependent probability of 3.0 ± 1.5% over the next 30 years compared to the time-independent probability of 1.66%. Half of the hanging wall area of the Sparta Fault can experience intensities ≥ IX, but belongs to the lowest category of seismic risk of the national seismic building code. On view of these relatively high calculated probabilities, a reassessment of the building code might be necessary.
Alexopoulos J, Vassilakis E, Dilalos S. Combined geophysical techniques for detailed groundwater flow investigation in tectonically deformed fractured rocks. Annals of Geophysics [Internet]. 2013;56:1-7. Abstract
In this paper we present a combination of several near surface geophysical investigation techniques with high resolution remote sensing image interpretations, in order to define the groundwater flow paths and whether they can be affected by future seismic events. A seasonal spring (Amvrakia) located at the foot of Meteora pillars near the village of Kastraki (Greece) was chosen as a test site. The Meteora conglomeratic formations crop out throughout the study area and are characterized by large discontinuities caused by post Miocene till present tectonic deformation [Ferriere et al. 2011, Royden and Papanikolaou 2011]. A network of groundwater pathways has been developed above the impermeable marls underlying the conglomeratic strata. Our research aims to define these water pathways in order to investigate and understand the exact mechanism of the spring by mapping the exposed discontinuity network with classic field mapping and remote sensing image interpretation and define their underground continuity with theΒ contribution of near surface geophysical techniques. Five Very Low Frequency (VLF) profiles were conducted with different directions around the spring aiming to detect possible conductive zones in the conglomeratic formations that the study area consists of. Moreover, two Electrical Resistivity Tomography (ERT) sections of a total length of 140m were carried out parallel to the VLF profiles for cross-checking and verifying the geophysical information. Both techniques revealed important conductive zones (<200 Ohm m) within the conglomerate strata, which we interpret as discontinuities filled with water supplying the spring, which are quite vulnerable to displacements as the hydraulic connections between them might be easily disturbed after a future seismic event.
Fountoulis I, Mavroulis S, Vassilakis E, Papadopoulou-Vrynioti K. Shoreline displacement and Pineios River diversions in NW Peloponnese (Greece) as result of the geology, active tectonics and human activity during the last 100 ky. Zeitschrift fur Geomorphologie, Supplementary Issues [Internet]. 2013;57:97-123.
Pineios River is the 3 rd longest river in Peloponnese and flows in Kyllini wider area which is located close to the Hellenic Arc-Trench system. This is one of the most seismically and tectonically active regions in Greece with a great number of changes in the morphogenetic events taking place during the neotectonic period, as well as the last 100 ky. Prior to the 18 th century A.D., the lower alluvial Pineios River flowed north of the Kyllini peninsula and into the Ionian Sea southwest of Kotichi Lagoon, but the river now flows southward into a deltaic swamp and dune region, burying a former lagoon-barrier coastal zone. From this, it becomes apparent that this river is not monotonous in appearance and therefore is not completely controlled by hydrology and hydraulics. In fact, the lower alluvial Pineios River has reacted to major geological controls, surface deformation and uplift movements caused by the activity of the recently mapped Pineios normal fault zone and salt tectonics in Kyllini peninsula resulting in the river flow diversion from north to south at completely different open sea areas. The effects of the geological, tectonic and neotectonic activity and the impact of the human presence and influence on the lower Pineios River are presented in this paper in order to determine the causes of the diversion of the lower (alluvial) Pineios River (NW Peloponnese, Greece) and shoreline displacements.
Bradley KE, Vassilakis E, Hosa A, Weiss BP. Segmentation of the Hellenides recorded by Pliocene initiation of clockwise block rotation in Central Greece. Earth and Planetary Science Letters [Internet]. 2013;362:6-19.
New paleomagnetic data from Early Miocene to Pliocene terrestrial sedimentary and volcanic rocks in Central Greece constrain the history of vertical-axis rotation along the central part of the western limb of the Aegean arc. The present-day pattern of rapid block rotation within a broad zone of distributed deformation linking the right-lateral North Anatolian and Kephalonia continental transform faults initiated after Early Pliocene time, resulting in a uniform clockwise rotation of 24.3±6.5° over a region >250 km long and >150 km wide encompassing Central Greece and the western Cycladic archipelago. Because the published paleomagnetic dataset requires clockwise rotations of >50° in Western Greece after ∼17 Ma, while our measurements resolve no vertical-axis rotation of Central Greece between ∼15 Ma and post-Early Pliocene time, a large part of the clockwise rotation of Western Greece must have occurred during the main period of contraction within the external thrust belt of the Ionian Zone between ∼17 and ∼15 Ma. Pliocene initiation of rapid clockwise rotation in Central and Western Greece reflects the development of the North Anatolia–Kephalonia Fault system within the previously extended Aegean Sea region, possibly in response to entry of dense oceanic lithosphere of the Ionian Sea into the Hellenic subduction zone and consequent accelerated slab rollback. The development of the Aegean geometric arc therefore occurred in two short-duration pulses characterized by rapid rotation and strong regional deformation.