Tectonic evolution and stress field of the Kymi-Aliveri basin, Evia island, Greece

Stress and strain analysis has been used to reconstruct the post-Oligocene geodynamics of the Kymi-Aliveri basin: The Kymi-Aliveri basin occupies the footwall of the Kymi-Thrust, which formed during the Middle Miocene as a large transpressional structure in the late orogenic stages of the Hellenides. Subsequently, in the Upper Miocene the shape of the basin was strongly modified by an orthogonal system of NE and NW trending normal faults as a result of post orogenic collapse. In the Pliocene and Pleistocene time the basin is a part of the back arc basin, which developed behind the Hellenic Arc. WNW trending normal faults and reactivated faults characterized this tectonic phase

PATTERNS OF DUCTILE DEFORMATION IN ATTICO-CYCLADIC MASSIF

The area of Lavrion constitutes the westernmost part of the Attico-Cycladic massif where the allochthonous Cycladic Greenschist-Blueschist unit overthrusts the para-authochthonous Basal unit. The tectonic contact of these units forms a crustal scale thrust zone which is the continuation of the Evia thrust. Our research was focused on quartz-rich schists of the overlying allochthonous unit. Combination of microstructural, finite strain data and quartz and calcite c-axis fabrics analysis was used to characterize the kinematics of rock flow within the thrust zone. The latter was formed under conditions of progressive exhumation and decompression of the high-pressure schists of the AtticoCycladic massif. A dominant top-to-the-ENE sense of shearing along the thrust zone is inferred by several shear sense criteria. The analysis of several specimens collected from various structural depths manifest that the deformation close to the thrust zone occurred under approximately plane strain conditions and was characterized by an Rxz strain ratio which fluctuates between 3 and 6.5

A comparison of terrestrial laser scanning and structure-from-motion photogrammetry as methods for digital outcrop acquisition

Terrestrial laser scanning (TLS) has been used extensively in Earth Science for acquisition of digital outcrop data over the past decade. Structure-from-­motion (SfM) photogrammetry has recently emerged as an alternative and competing technology. The real-world performance of these technologies for ground-based digital outcrop acquisition is assessed using outcrops from North East England and the United Arab Emirates. Both TLS and SfM are via­ble methods, although no single technology is universally best suited to all situations. There are a range of practical considerations and operating conditions where each method has clear advantages. In comparison to TLS, SfM benefits from being lighter, more compact, cheaper, more easily replaced and repaired, with lower power requirements. TLS in comparison to SfM provides intrinsically validated data and more robust data acquisition in a wide range of operating conditions. Data post-processing is also swifter. The SfM data sets were found to contain systematic inaccuracies when compared to their TLS counterparts. These inaccuracies are related to the triangulation approach of the SfM, which is distinct from the time-of-flight principle employed by TLS. An elaborate approach is required for SfM to produce comparable results to TLS under most circumstances

Palaeoseismological investigations of Aegean-type active faults.

Palaeoseismological studies carried out in the Aegean Region during the past decade or so, mainly from faults lying in mainland Greece, are reconsidered and their results re-evaluated. We focus on active normal faults and particularly on the principal seismotectonic parameters, such as the coseismic displacement associated to past events and the length of the seismogenic structures. Based on new both field observations and existing data and following few assumptions, we attempt to calculate the maximum seismic moment possibly associated to past earthquakes and documented from palaeoseismological studies. These seismic moments are compared with those estimated from historical earthquakes for which both maximum vertical displacement and surface rupture length are known. Similarities and differences of the two datasets are discussed, showing that palaeoseismologically-calculated magnitudes and displacements per event appear to be systematically underestimated in the Aegean Region as well as their seismic potential. For selected faults, we also obtained reliable values of the recurrence interval of moderate to large earthquakes and estimates of the slip-rate. Differences in these parameters are attributed to the different geotectonic settings