Papers by Haralambos Kranis
The onshore central Corinth rift contains a syn-rift succession >3 km thick deposited in 5–15 km-... more The onshore central Corinth rift contains a syn-rift succession >3 km thick deposited in 5–15 km-wide tilt blocks, all now inactive, uplifted and deeply incised. This part of the rift records upward deepening from fluviatile to lake-margin conditions and finally to sub-lacustrine turbidite channel and lobe complexes, and deep-water lacustrine conditions (Lake Corinth) were established over most of the rift by 3.6 Ma. This succession represents the first of two phases of rift development – Rift 1 from 5.0–3.6 to 2.2–1.8 Ma and Rift 2 from 2.2–1.8 Ma to present. Rift 1 developed as a 30 km-wide zone of distributed normal faulting. The lake was fed by four major N-to NE-flowing antecedent drainages along the southern rift flank. These sourced an axial fluvial system, Gilbert fan deltas and deep lacustrine turbidite channel and lobe complexes. The onset of Rift 2 and abandonment of Rift 1 involved a 30 km northward shift in the locus of rifting. In the west, giant Gilbert deltas built into a deepening lake depocentre in the hanging wall of the newly developing southern border fault system. Footwall and regional uplift progressively destroyed Lake Corinth in the central and eastern parts of the rift, producing a staircase of deltaic and, following drainage reversal, shallow marine terraces descending from >1000 m to present-day sea level. The growth, linkage and death of normal faults during the two phases of rifting are interpreted to reflect self-organization and strain localiza-tion along co-linear border faults. In the west, interaction with the Patras rift occurred along the major Patras dextral strike-slip fault. This led to enhanced migration of fault activity, uplift and incision of some early Rift 2 fan deltas, and opening of the Rion Straits at ca. 400–600 ka. The landscape and stratigraphic evolution of the rift was strongly influenced by regional palaeotopographic variations and local antecedent drainage, both inherited from the Hellenide fold and thrust belt.
Early Pleistocene synrift deltas developed along the southern Corinth rift margin were deposited ... more Early Pleistocene synrift deltas developed along the southern Corinth rift margin were deposited in a single, dominantly lacustrine depocenter and were subject to the same climate-related base-level and sediment supply cyclicity. Two synrift deltas, just 50 km apart, show markedly different sequence geometry and evolution related to their location along the evolving border fault. In the west, strongly aggradational fan deltas (>600 m thick; 2–4 km radius) deposited in the immediate hanging wall of the active border fault comprise stacked 30–100 m thick stratal units bounded by flooding surfaces. Each unit evolves from aggradational to progradational with no evidence for abrupt subaerial exposure or fluvial incision. In contrast , in the central rift, the border fault propagated upward into an already deep lacustrine environment, locating rift-margin deltas 15 km into the footwall. The deltas here have a radius of >9 km and comprise northward downstepping and offlapping units, 50–200 m thick, that unconformably overlie older synrift sediments and are themselves incised. The key factors driving the marked variation in sequence stratigraphic architecture are: (1) differential uplift and subsidence related to position with respect to the border fault system , and (2) inherited topography that influenced shoreline position and offshore bathymetry. Our work illustrates that stratal units and their bounding surfaces may have only local (<10 km) extent, highlighting the uncertainty involved in assigning chronostratigraphic significance to systems tracts and in calculating base-level changes from stratigraphy where marked spatial variations in uplift and subsidence occur.
The Corinth Rift, central Greece, enables analysis of early rift development as it is young (<5 M... more The Corinth Rift, central Greece, enables analysis of early rift development as it is young (<5 Ma) and highly active and its full history is recorded at high resolution by sedimentary systems. A complete compilation of marine geophysical data, complemented by onshore data, is used to develop a high-resolution chronostratigraphy and detailed fault history for the offshore Corinth Rift, integrating interpretations and reconciling previous discrepancies. Rift migration and localization of deformation have been significant within the rift since inception. Over the last circa 2 Myr the rift transitioned from a spatially complex rift to a uniform asymmetric rift, but this transition did not occur synchronously along strike. Isochore maps at circa 100 kyr intervals illustrate a change in fault polarity within the short interval circa 620–340 ka, characterized by progressive transfer of activity from major south dipping faults to north dipping faults and southward migration of discrete depocenters at ~30 m/kyr. Since circa 340 ka there has been localization and linkage of the dominant north dipping border fault system along the southern rift margin, demonstrated by lateral growth of discrete depocenters at ~40 m/kyr. A single central depocenter formed by circa 130 ka, indicating full fault linkage. These results indicate that rift localization is progressive (not instantaneous) and can be synchronous once a rift border fault system is established. This study illustrates that development processes within young rifts occur at 100 kyr timescales, including rapid changes in rift symmetry and growth and linkage of major rift faults.
We present a unified and homogeneous digital aeromagnetic map of the Hellenic mainland, based on ... more We present a unified and homogeneous digital aeromagnetic map of the Hellenic mainland, based on the 1:50,000 map series of IGME. These maps cover the areas A1, A2, B, C1, C2, C3, D1 compiled by Hunting Geology and Geophysics Ltd. and measured at nominal ground clearances (flight altitudes) 150m AGL, 150m AGL, 300m AGL, and 2300m AMSL respectively (part of C2 with 3000m AMSL). We also include the entire area of Northern Greece, measured by ABEM AB with nominal ground clearance 275±75m AGL. The original map sheets were digitally imaged, georeferenced, digitized along contour lines and interpolated onto regular 250´250m grids. The unified aeromagnetic map was constructed by collating the mosaic of the resulting gridded data. Using upward/downward continuation techniques various homogeneous versions of the map, were compiled by referencing of the observed mosaic total magnetic field to a unique constant ground clearance or to a unique constant elevation above mean sea level. This is the first time there is a complete and unified
image of the magnetic signature of the isopic zones and rock formations comprising the Hellenic mainland, with particular reference to the ophiolite suites, which provides additional insight into the Alpine and post-alpine tectonics of the area.
The linkage between tectonism and erosion may lead to the extraction of quantitative information ... more The linkage between tectonism and erosion may lead to the extraction of quantitative information on the uplift rate of a fault block, based on the current relief. For this purpose different methodologies have been developed,relating the differential block uplift with the eroding pattern of the stream channels. High resolution DEMs are used for the calculation of several morphometric parameters providing a powerful tool for the exact delimitation of neotectonic structures and potentially the estimation of the uplift rate. The transition from the published theory to the accurate estimation of these geomorphometric indices is a complicated series of procedures based on calculations between arrays of pixels and visualize the results on a GIS platform. Some of the final images produced for this paper were not reliable for further interpretation because of the objective difficulty of expressing all the landforms with a table of numbers.
The Corinth Rift, central Greece, enables analysis of early rift development as it is young (<5 M... more The Corinth Rift, central Greece, enables analysis of early rift development as it is young (<5 Ma) and highly active and its full history is recorded at high resolution by sedimentary systems. A complete compilation of marine geophysical data, complemented by onshore data, is used to develop a high-resolution chronostratigraphy and detailed fault history for the offshore Corinth Rift, integrating interpretations and reconciling previous discrepancies. Rift migration and localization of deformation have been significant within the rift since inception. Over the last circa 2 Myr the rift transitioned from a spatially complex rift to a uniform asymmetric rift, but this transition did not occur synchronously along strike. Isochore maps at circa 100 kyr intervals illustrate a change in fault polarity within the short interval circa 620-340 ka, characterized by progressive transfer of activity from major south dipping faults to north dipping faults and southward migration of discrete depocenters at~30 m/kyr. Since circa 340 ka there has been localization and linkage of the dominant north dipping border fault system along the southern rift margin, demonstrated by lateral growth of discrete depocenters at~40 m/kyr. A single central depocenter formed by circa 130 ka, indicating full fault linkage. These results indicate that rift localization is progressive (not instantaneous) and can be synchronous once a rift border fault system is established. This study illustrates that development processes within young rifts occur at 100 kyr timescales, including rapid changes in rift symmetry and growth and linkage of major rift faults.
The spatial-temporal evolution of seismicity is examined, during the initial impoundment of Pourn... more The spatial-temporal evolution of seismicity is examined, during the initial impoundment of Pournari reservoir located on Arachthos River (Western Greece), as well as for the next 30 years. The results show that, despite the relatively moderate-to-high seismicity from west to east, there is no remarkable earthquake in the vicinity before the first reservoir impoundment. Immediately after the impoundment (January 1981), and during the first 4 months, a considerable number of low-magnitude seismic events were recorded in the broader area of the dam. Moreover, two independent major events occurred on March 10, 1981 (M L = 5.6) and April 10, 1981 (M L = 4.7) with focal depths 13 and 10 km, respectively. The detailed analysis of the two corresponding aftershock sequences shows that they present different behaviors (e.g., larger b-value and lower magnitude of the main aftershock) than that of other aftershock sequences in Greece. This seismicity is probably due to triggering, via the water loading mechanism and the undrained response due to a flysch appearance on the reservoir basement. The activation of the thrust fault may be attributed to the bulging of evaporites that characterize the disordered structure of W. Greece, via possible water intake. The detailed processing of the recorded seismicity during the period 1982–2010, in comparison with the variations of Pournari Dam water level, shows an increase of shallow seismicity (h ≤ 5 km) in the vicinity of the reservoir up to a 10-km distance— in contrast to the initial period, characterized by a number of deeper events due to the background response change from undrained to drained status.
Geomorphology, Jan 1, 2006
This work presents the results of gravity, TEM and geological surveys conducted in the area of Ma... more This work presents the results of gravity, TEM and geological surveys conducted in the area of Marathon - Kato Souli Plain, as part of an effort to study its hydrogeological characteristics. The gravity survey offered a rather detailed image of the alpine basement and together with surface geological observations, insight into the post-alpine tectonic processes that have controlled the development of the area. The TEM survey produced detailed three-dimensional images of the aquifer systems and salination conditions. The results have shown that (a) the alpine basement is located much deeper than previously thought and, (b) that the sea water intrusion takes place both near sea level and at depth. The depth and morphology of the alpine basement are believed to have been fashioned by faults that either have not been active during the Quaternary, or are buried under thick terrestrial and alluvial deposits. Sea water intrusion forms at least two distinct salination horizons, presumably a...
CRUSTAL DEFORMATION IN THE BROADER ATALANTI AREA (GREECE) V. Sakkas1, M. Pirli1, S. Vassilopoulou... more CRUSTAL DEFORMATION IN THE BROADER ATALANTI AREA (GREECE) V. Sakkas1, M. Pirli1, S. Vassilopoulou1, G. Kaviris1, C. Kranis2, N. Voulgaris1, P. Papadimitriou1, E. Lagios1 & K. Makropoulos1 1 Department of Geophysics, University of Athens, Panepistimiopolis, 15784 Athens Greece. 2 Department of Tectonics, University of Athens, Panepistimiopolis, 15784 Athens Greece. Abstract Evoikos Gulf is a NW-SE trending graben that separates Evia Island from Central Greece. Distractive earthquakes occurred in the area since the antiquity. The broader area of the Atalanti Faulting Zone (from Kamena Vourla to Larymna) is controlled by six main faulting zones: Kamena Vourla, Agios Konstantinos, Arkitsa, Hyampolis, Atalanti and Malessina. The last large and destructive earthquake sequence occurred in the area on 1894, with two large shocks on 20th and 27th of April (M=6.7 and 7.0, respectively). Small ruptures, cracks and landslides were produced from the first shock, mainly in Malessina peninsula alo...
Journal of Geodynamics, 2010
We report the results of a joint analysis of aeromagnetic, topographic and tectonic data in centr... more We report the results of a joint analysis of aeromagnetic, topographic and tectonic data in central-eastern mainland Greece. The emphasis of the analysis is placed on the detection of coherent lineations (discontinuities), collocated and correlated with faulting structures detected by geological field observation. To this effect, edge detection and image enhancement were applied to digital aeromagnetic anomaly maps and digital elevation models, comprising bidirectional differentiation, wavelet transformation (imaging) and spatial decomposition/reconstruction in the wavenumber domain. The analysis facilitated the detection of significant topographic lineaments with NNE-SSW, ENE-WSW and ESE-WNW orientations. Respectively, the aeromagnetic data exhibit two families of significant NE-SW, and one family of ESE-WNW lineaments. The major aeromagnetic and topographic lineaments coincide and have comparable width scales of the order of 2-3 km, indicating that they are produced by significant discontinuities in the upper crust. The kinematics of the NE-SW faults varies between oblique-slip and strike-slip. These faults affect Neogene to Late Quaternary deposits and have been responsible for the formation of transverse depressions and horsts. This is also corroborated by focal plane solutions from small earthquakes recorded by local networks. The nature of these structures is not yet clear. However, they have been detected by diverse methodologies, they have considerable extent and are apparently active. These attributes suggest that they may possibly be related to the propagation and diffusion of the North Anatolian and North Aegean fault systems into the Greek mainland.
Continental rift deposits contain critical clues concerning the evolution of extensional tectonic... more Continental rift deposits contain critical clues concerning the evolution of extensional tectonics, yet such evidence is often obscure due to poor geochronology, burial by younger deposits, or later tectonic overprinting. We revisit Corinth rift development, which began as distributed extension created synrift depocenters with rivers flowing into shallow (<50 m) lakes. Subsequent focused deformation initiated a "Great Deepening" event, evidenced by fan deltas prograding into 300–600-m-deep water. A chronology is provided for the event from 40Ar/39Ar dating of the Xylocastro ash by single-crystal CO2 laser fusion, yielding a precise age of 2.550 ± 0.007 Ma (1σ, full error propagation). Sedimentological data indicate that the ash-bearing sediments were deposited as turbidites and hemipelagites on sublacustrine fans fed from the Mavro fan delta at the faulted south-central rift margin. The ash age and turbidite provenance data enable stratigraphic constraints for an estimate of central rift climax occurring between 3.2 and 3.0 Ma. This is some 0.8–1.0 m.y. earlier than radioisotopic- and magnetostratigraphic-constrained estimates for the eastern Corinth rift. Central rift climax was probably triggered by initial counterclockwise rotation of the Peloponnesus block with respect to central Greece. The rotation pole of this block subsequently migrated to its present position as rift climax moved eastward in an "unzipping" action, with the southern active margin also migrating northward. These events are unlikely to be due to local or regional fault kinematics, but rather to the consequences of deep-seated interactions between the rapidly southward-moving Aegean continental forearc and the slowly northward-subducting African oceanic plate. A possible scenario involves forearc "pushback" with décollement on a low-angle subducting lower plate. This causes acceleration and counterclockwise rotation of Peloponnesus with respect to central Greece and strain localization across the boundary; the Corinth rift.
Geological Society London Special …, Jan 1, 2009
Extensional structures with geometrical and kinematic features analogous to the known Gulf of Cor... more Extensional structures with geometrical and kinematic features analogous to the known Gulf of Corinth faults, are found further to the south of what is considered to be the southern margin of the of Proto-Corinth Gulf, reaching south to the northern flanks of Mt Mainalon. This mountain front is marked by the North Mainalon Fault Zone, which comprises a series of normal fault segments with NNE dips. Assuming a listric or ramp-flat geometry for the North Mainalon Fault Zone, it could flatten at a depth of 6–8 km, underneath Mt Khelmos. Its southern, shallow part has been truncated by NNE- and NNW-trending faults, which may be linked to northward propagation of the east–west extension in the Southern Peloponnesus, causing further uplift in the central and northern Peloponnesus, while its deeper part is still active and may reach further north and sole onto the hypothesized detachment zone beneath the Gulf
of Corinth.
Observations in trenches excavated across the Ekkara rupture zone (ERZ), the longest of the spora... more Observations in trenches excavated across the Ekkara rupture zone (ERZ), the longest of the sporadic ground ruptures that accompanied the M 6.7–7.0 earthquake of 30 April 1954 on the Domokos fault zone (DFZ), identify a left-lateral oblique-normal fault with a slip vector aligned with the regional extension direction (verifying the tectonic origin of the ERZ). The paleoseismological interpretation of stratigraphic, soil-stratigraphic, and tectonic features is discussed with emphasis on the issues related to strongly oblique fault kinematics. Two pre-1954 events of ground rupture are recognized (E1 and E2) and an event of ground cracking only (E1a, shortly after E1). Event E2 was accompanied by larger displacement than E1 and 1954, but this does not necessarily imply a stronger earthquake. Archaeological dating of transported ceramic sherds constrains E1 between 6750 and 4450 B.P. (more likely, 6450–5750 B.P.). Luminescence dating of colluvial deposits and 14C dating of pedogenic carbonates (stone coatings) place E2 at ∼17,500 +− ∼2500 B.P. (preferred age). In the (hazard-wise) most conservative interpretation, recent recurrence intervals of ERZ activations exceed 3195 years. The sporadic nature of the 1954 ruptures precludes certainty on whether the ERZ has recorded every past activation of the DFZ unless data are also collected from other DFZ rupture zones. Minimum-limiting estimates of 0.3–0.5 mm/yr slip rate are derived for the ERZ, and the true slip rate is not expected to exceed 1 mm/yr. Slip rate estimates for the ERZ may be minima for the DFZ slip rate, however, because coseismic deformation in the past may have been distributed to more than one rupture zones at the surface.
The neotectonic evolution of central-eastern mainland Greece (Sterea Hellas) is documented in the... more The neotectonic evolution of central-eastern mainland Greece (Sterea Hellas) is documented in the result of local extensional tectonics within a regional transten-sional field, which is related to the westward propagation of the North Anatolian Fault. The observed tectonic, structures within the neotectonic basins and their mar-gins (range-bounding faults and fault zones, rotation of tectonic blocks) suggest a close relation to the Parnassos Detachment Fault (PDF), which is a reused alpine thrust surface. Lokris basin (LB) occupied a central position in this neotectonic con-figuration, having received its first sediments in the Uppermost Miocene and subse-quently been greatly affected by tectonic episodes, which continue until nowadays. LB is considered to have been separated from the present-day North Gulf of Evia not earlier than the Lower Pleistocene. Voiotikos Kifissos Basin, on the other hand, is tightly related to the activation of PDF, occupying the position of a frontal basin and having developed along the main detachment front
The kinematics of active faults in central-eastern mainland Greece suggests that the range-boundi... more The kinematics of active faults in central-eastern mainland Greece suggests that the range-bounding faults are oblique-normal, rather than purely dip-slip. The tectonic fabric is consistent with elongated block rotation, which can be controlled by a NE-SW, 30-km wide crustal-scale shear zone that may accommodated the westward extrusion of the Anatolian plate into the Aegean.
Egio earthquake (15 June 1995) produced a series of destructive geological surficial effects in n... more Egio earthquake (15 June 1995) produced a series of destructive geological surficial effects in northern Peloponnessos and southern Sterea Hellas. After a brief review on the current opinions on the tectonic regime of the area has been made, we give a description of these effects, focusing mainly on the fractures along the Egio fault. Then, we present a model to interpret the earthquake activity of 15 June 1995; finally a discussion concerning the extensional tectonic regime of the area is made based on seismic data, the geometry of onshore and the recently described offshore faults.
Journal of Geodynamics, Jan 1, 2010
We report the results of a joint analysis of aeromagnetic, topographic and tectonic data in centr... more We report the results of a joint analysis of aeromagnetic, topographic and tectonic data in central-eastern mainland Greece. The emphasis of the analysis is placed on the detection of coherent lineations (discontinuities), collocated and correlated with faulting structures detected by geological field observation. To this effect, edge detection and image enhancement were applied to digital aeromagnetic anomaly maps and
digital elevation models, comprising bidirectional differentiation, wavelet transformation (imaging) and spatial decomposition/reconstruction in the wavenumber domain. The analysis facilitated the detection of significant topographic lineaments with NNE–SSW, ENE–WSW and ESE–WNW orientations. Respectively, the aeromagnetic data exhibit two families of significant NE–SW, and one family of ESE–WNW
lineaments. The major aeromagnetic and topographic lineaments coincide and have comparable width scales of the order of 2–3 km, indicating that they are produced by significant discontinuities in the upper crust. The kinematics of the NE–SW faults varies between oblique-slip and strike-slip. These faults affect Neogene to Late Quaternary deposits and have been responsible for the formation of transverse depressions and horsts. This is also corroborated by focal plane solutions from small earthquakes recorded by local networks. The nature of these structures is not yet clear. However, they have been detected by diverse methodologies, they have considerable extent and are apparently active. These attributes suggest that they may possibly be related to the propagation and diffusion of the North Anatolian and North Aegean fault systems into the Greek mainland.
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Papers by Haralambos Kranis
image of the magnetic signature of the isopic zones and rock formations comprising the Hellenic mainland, with particular reference to the ophiolite suites, which provides additional insight into the Alpine and post-alpine tectonics of the area.
of Corinth.
digital elevation models, comprising bidirectional differentiation, wavelet transformation (imaging) and spatial decomposition/reconstruction in the wavenumber domain. The analysis facilitated the detection of significant topographic lineaments with NNE–SSW, ENE–WSW and ESE–WNW orientations. Respectively, the aeromagnetic data exhibit two families of significant NE–SW, and one family of ESE–WNW
lineaments. The major aeromagnetic and topographic lineaments coincide and have comparable width scales of the order of 2–3 km, indicating that they are produced by significant discontinuities in the upper crust. The kinematics of the NE–SW faults varies between oblique-slip and strike-slip. These faults affect Neogene to Late Quaternary deposits and have been responsible for the formation of transverse depressions and horsts. This is also corroborated by focal plane solutions from small earthquakes recorded by local networks. The nature of these structures is not yet clear. However, they have been detected by diverse methodologies, they have considerable extent and are apparently active. These attributes suggest that they may possibly be related to the propagation and diffusion of the North Anatolian and North Aegean fault systems into the Greek mainland.
image of the magnetic signature of the isopic zones and rock formations comprising the Hellenic mainland, with particular reference to the ophiolite suites, which provides additional insight into the Alpine and post-alpine tectonics of the area.
of Corinth.
digital elevation models, comprising bidirectional differentiation, wavelet transformation (imaging) and spatial decomposition/reconstruction in the wavenumber domain. The analysis facilitated the detection of significant topographic lineaments with NNE–SSW, ENE–WSW and ESE–WNW orientations. Respectively, the aeromagnetic data exhibit two families of significant NE–SW, and one family of ESE–WNW
lineaments. The major aeromagnetic and topographic lineaments coincide and have comparable width scales of the order of 2–3 km, indicating that they are produced by significant discontinuities in the upper crust. The kinematics of the NE–SW faults varies between oblique-slip and strike-slip. These faults affect Neogene to Late Quaternary deposits and have been responsible for the formation of transverse depressions and horsts. This is also corroborated by focal plane solutions from small earthquakes recorded by local networks. The nature of these structures is not yet clear. However, they have been detected by diverse methodologies, they have considerable extent and are apparently active. These attributes suggest that they may possibly be related to the propagation and diffusion of the North Anatolian and North Aegean fault systems into the Greek mainland.