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Sorel, D.
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- PublicationOpen AccessGeomorphological evidence of fast Holocene coastal uplift at the western termination of the Corinth Rift (Greece): constraints on minimum Holocene uplift rate and potential paleoseismological significance(2007)
; ; ; ; ; ;Palyvos, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Lemeille, F.; IRSN ;Sorel, D.; Université Paris Sud ;Pantosti, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Pavlopoulos, K.; Harokopio University; ; ; ; The westernmost part of the Gulf of Corinth (Greece) is an area of very fast extension (~15 mm/yr according to geodetic measurements) and active normal faulting, accompanied by intense coastal uplift and high seismicity. This study presents geomorphic and biological evidence of Holocene coastal uplift at the western extremity of the Gulf, where such evidence was previously unknown. Narrow shore platforms (benches) and rare notches occur mainly on Holocene littoral conglomerates of uplifting small fan deltas. They are perhaps the only primary paleoseismic evidence likely to provide information on earthquake recurrence at coastal faults in the specific part of the Rift system, whereas dated marine fauna can provide constraints on average Holocene coastal uplift rate. The types of geomorphic and biological evidence identified are not ideal, and there are limitations and pitfalls involved in their evaluation. In a first approach, 5 uplifted paleoshorelines may be indentified, at 0.4- 0.7, 1.0-1.3, 1.4-1.7, 2.0-2.3 and 2.8-3.4 m a.m.s.l. They probably formed after 1728 or 2250 Cal. B.P. (depending on the marine reservoir correction used in the calibration of measured radiocarbon ages). A most conservative estimate for the average coastal uplift rate during the Late Holocene is 1.6 or 1.9 mm/yr minimum (with different amounts of reservoir correction). Part of the obtained radiocarbon ages of Lithophaga sp. allows for much higher Holocene uplift rates, of the order of 3-4 mm/yr, which cannot be discarded given that similar figures exist in the bibliography on Holocene and Pleistocene uplift at neighbouring areas. They should best be cross-checked by further studies though. That the identified paleoshoreline record corresponds to episodes of coastal uplift only, cannot be demonstrated beyond all doubt by independent evidence, but it appears the most likely interpretation, given the geological and active-tectonic context and, what is known about eustatic sea-level fluctuations in the Mediterranean. Proving that the documented uplifts were abrupt (i.e., arguably coseismic), is equally difficult, but reasonably expected and rather probable. Five earthquakes in the last ca. 2000 yrs on the coastal fault zone responsible for the uplift, compare well with historical seismicity and the results of recent on-fault paleoseismological studies at the nearby Eliki fault zone. Exact amounts of coseismic uplift cannot be determined precisely, unless the rate of uniform ("regional") non-seismic uplift of Northern Peloponnesus at the specific part of the Corinth Rift is somehow constrained.190 181 - PublicationOpen AccessUsing geomorphic and biological indicators of coastal uplift for the evaluation of paleoseismicity and(2007)
; ; ; ; ; ;Palyvos, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Lemeille, F.; IRSN (France) ;Sorel, D.; Université Paris Sud ;Pantosti, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Pavlopoulos, K.; Harokopio University; ; ; ; The westernmost part of the Gulf of Corinth (Greece) is an area of very fast extension (~15 mm/yr according to geodetic measurements) and active normal faulting, accompanied by intense coastal uplift and high seismicity. This study presents geomorphic and biological evidence of Holocene coastal uplift at the western extremity of the Gulf, where such evidence was previously unknown. Narrow shore platforms (benches) and rare notches occur mainly on Holocene littoral conglomerates of uplifting small fan deltas. They are perhaps the only primary paleoseismic evidence likely to provide information on earthquake recurrence at coastal faults in the specific part of the Rift system, whereas dated marine fauna can provide constraints on average Holocene coastal uplift rate. The types of geomorphic and biological evidence identified are not ideal, and there are limitations and pitfalls involved in their evaluation. In a first approach, 5 uplifted paleoshorelines may be indentified, at 0.4- 0.7, 1.0-1.3, 1.4-1.7, 2.0-2.3 and 2.8-3.4 m a.m.s.l. They probably formed after 1728 or 2250 Cal. B.P. (depending on the marine reservoir correction used in the calibration of measured radiocarbon ages). A most conservative estimate for the average coastal uplift rate during the Late Holocene is 1.6 or 1.9 mm/yr minimum (with different amounts of reservoir correction). Part of the obtained radiocarbon ages of Lithophaga sp. allows for much higher Holocene uplift rates, of the order of 3-4 mm/yr, which cannot be discarded given that similar figures exist in the bibliography on Holocene and Pleistocene uplift at neighbouring areas. They should best be cross-checked by further studies though. That the identified paleoshoreline record corresponds to episodes of coastal uplift only, cannot be demonstrated beyond all doubt by independent evidence, but it appears the most likely interpretation, given the geological and active-tectonic context and, what is known about eustatic sea-level fluctuations in the Mediterranean. Proving that the documented uplifts were abrupt (i.e., arguably coseismic), is equally difficult, but reasonably expected and rather probable. Five earthquakes in the last ca. 2000 yrs on the coastal fault zone responsible for the uplift, compare well with historical seismicity and the results of recent on-fault paleoseismological studies at the nearby Eliki fault zone. Exact amounts of coseismic uplift cannot be determined precisely, unless the rate of uniform ("regional") non-seismic uplift of Northern Peloponnesus at the specific part of the Corinth Rift is somehow constrained.187 271 - PublicationRestrictedReview and new data on uplift rates at the W termination of the Corinth Rift and the NE Rion Graben area (Achaia, NW Peloponnesos)(2007-05)
; ; ; ; ; ; ; ; ;Palyvos, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Sorel, D.; Université Paris-Sud, Faculty of Geology ;Lemeille, F.; Institut de Radioprotection et de Surete Nucléaire, Seismic Hazard Division ;Mancini, M.; CNR- Istituto di Geologia Ambientale e Geoingenieria ;Pantosti, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Julia, R.; Institute of Earth Sciences Jaume Almera, Barcelona ;Triantaphylou, M.; national and Capodistrian Univesrity of Athens, Faculty of Geology and Geoenvironment ;De Martini, P. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ; We review and present new geochronological data on the uplifted Middle-Late Pleistocene marine deposits at the western termination of the Corinth Rift and the Rion area. Geomorphological and geological observations define the general morphotectonic context of these deposits, which predicts a pattern of differential uplift. Uplift rate estimates based on previous geochronological data (ranging from 0.4 to 6 mm/yr) are discussed in the proposed morphotectonic context of differential uplift, together with estimates from new geochronological data. Based on the data available for post-MIS11 marine deposits, we conclude that time-averaged uplift rates in the last 300-200 ka have been higher than ca. 1.8 mm/yr at the areas of faster uplift (e.g. Profitis Elias, Ano Kastritsi). To define just how higher than 1.8 mm/yr they have been, and to cross-check the validity of very high uplift rate estimates (≥ 4 mm/yr) existing in the bibliography, more datings than those available are required.150 26 - PublicationRestrictedThe Aigion–Neos Erineos coastal normal fault system (western Corinth Gulf Rift, Greece): Geomorphological signature, recent earthquake history, and evolution(2005-11-14)
; ; ; ; ; ; ;Palyvos, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Pantosti, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;De Martini, P. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Lemeille, F.; Seismic Hazard Division, Institut de Radioprotection et de Sureté Nucléaire, Fontenay-aux-roses, France ;Sorel, D.; Centre d’Orsay, Université Paris-Sud XI, Orsay, France ;Pavlopoulos, K.; Faculty of Geography, Harokopion University, Athens, Greece; ; ; ; ; At the westernmost part of the Corinth Rift (Greece), an area of rapid extension and active normal faulting, geomorphological observations reveal the existence and geometry of an active NW-SE trending coastal fault system, which includes the Aigion fault. We recognize a similar fault pattern on both the coastal range front to the NW of Aigion town and the Holocene fan deltas in front of it. We interpret this as a result of recent migration of faulting to the hanging wall of the fault system. Differences in the geomorphic expression of the constituent faults provide hints on the possible evolution of the fault pattern during this recent migration. A trench excavated across one of the identified coastal fault scarps (on a Holocene fan delta) provides information on the seismic history of the fault system, which includes at least four (possibly six) earthquakes in the past 4000 years. A minimum estimate for the slip rate of the trenched fault is 1.9–2.7 mm/yr. The trench exposed sediments of an uplifted paleolagoon (approximate age 2000 years B.P.), inside which the last two earthquakes formed an underwater monoclinal scarp. Oscillating coastal vertical movements are suggested by the fact that the lagoonal deposits are also uplifted on the trenched fault hanging wall (uplift by offshore faults) and by the abrupt transition from fluvial to lagoonal deposits (subsidence by more landward faults, assuming that extensive coastal sediment failure has not taken place in the specific part of the fan delta, within the time interval of interest). These movements suggest that the proposed migration of activity from the range front faults to those on the fan deltas is probably still ongoing, with activity on both sets of faults.269 33 - PublicationOpen AccessGeomorphological, stratigraphic and geochronological evidence of fast Pleistocene coastal uplift in the westernmost part of the Corinth Gulf Rift (Greece)(2009)
; ; ; ; ; ; ; ; ;Palyvos, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Mancini, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Sorel, D.; Université Paris-Sud, Centre d'Orsay, Faculty of Geology ;Lemeille, F.; Institut de Radioprotection et de Surete Nucléaire, Seismic Hazard Division, Fontenay-aux-roses ;Pantosti, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Julia, R.; Institute of Earth Sciences Jaume Almera, Barcelona ;Triantaphyllou, M.; National and Kapodistrian University of Athens ;De Martini, P. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ; Rapid extension and active normal faulting in the western extremity of the Corinth Gulf are accompanied by fast coastal uplift.We investigate Pleistocene uplift west of Aigion, by attempting to date remains of marine terraces and sedimentary sequences by calcareous nannoplankton and U-series analyses. Net uplift initiated recently, due to abandonment of an older rift-bounding fault zone and increase in activity on the presently active, coastal fault zone. This change apparently coincides with an abrupt slow down (or, termination) of secondary fault block tilting within the broader hangingwall block of the older zone, indicated by an angular unconformity that dates in the early part ofMIS10 ( 390–350 ka BP, preferably, in the earlier part of this period). Net uplift driven by the coastal zone resulted in the formation of MIS9c (330 ka) and younger terraces. The formation of the unconformity and the initiation of net uplift coincide temporally with a 300–400 ka unconformity recognized by recent studies in a wide area offshore Aigion i.e. they could be part of an evolutionary event that affected the entirewestern part of the Corinth Rift or, a large area therein. Uplift rate estimates at four locations are discussed with reference to the morphotectonic context of differential uplift of secondary fault blocks, and the context of possible increase in uplift ratewith time. Themost reliable and most useful estimate for uplift rate at the longitude of the studied transect is 1.74–1.85mm/year (time-averaged estimate for the last 240 ka, based on calcareous nannoplankton and sequence-stratigraphic interpretation)239 587