The Aigion–Neos Erineos coastal normal fault system (western Corinth Gulf Rift, Greece): Geomorphological signature, recent earthquake history, and evolution

Abstract

[1] 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.

Active faulting at the western tip of the Gulf of Corinth, Greece, from high-resolution seismic data

“…2). Our seismic lines tie with Bell et al's (2009) data set, therefore a direct correlation with our data set is possible and allows to estimate the age of our Ford et al (2009Ford et al ( , 2013, Palyvos et al (2005Palyvos et al ( , 2008, Flotté et al (2005), and references therein. Main offshore faults from Flotté et al (2005) for the Gulf of Patras, this study, McNeill et al (2005a), Bell et al (2008), and Taylor et al (2011 for the Western and Central Gulf of Corinth.…”

“…10). A minimum estimate of slip rate of 1.9-2.7 mm yr −1 for the last~2000 years has been proposed for the Selianitica scarp, located in the center of the Kamarai fault system (Palyvos et al, 2005). Subsidence rates associated to the Marathias fault are higher.…”

“…This discrepancy may have several origins. First, the Kamarai fault slip rate is a minimum estimate and it was obtained on a relatively short timeperiod (Palyvos et al, 2005). Second, the comparison between the slip rates of the main N-dipping and S-dipping faults in this part of the rift does not consider the influence of the Managouli fault zone, which is difficult to unravel.…”

“…1). Late Quaternary slip rates of these faults have been estimated at about 1.9-2.7 mm yr −1 (Kamari fault system), 0.3-2.0 to 7-11 mm yr − 1 (Eliki faults), and 1.6-6.3 to 9-11 mm yr −1 (Aigion fault) based on the analysis of trenches (Koukouvelas et al, 2001(Koukouvelas et al, , 2005(Koukouvelas et al, , 2008Pantosti et al, 2004;Palyvos et al, 2005) and uplifted shorelines combined with dislocation modeling Marine Geology 360 (2015) [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69] , respectively. The activity of the Trizonia fault is unknown, and its footwall is now subsiding at a rate of 5 ± 2 mm yr −1 according to GPS measurements (Moretti et al, 2003;Bernard et al, 2006).…”

Assessment of the sensitivity of the southern coast of the Gulf of Corinth (Peloponnese, Greece) to sea-level rise

“…The 12 km long Ai- gion fault and its offshore extension dictates the coastal geomorphology of the broader Aigion area. Study of a trench excavated across the fault led to the estimation of a minimum slip rate of 1.9 -2.7 mm/yr, which corresponds to a mean uplift rate of 1.4 mm/yr [51]. Through coastal geomorphic and biological indicators, an average Late Holocene coastal uplift ranging between 1.6 and 1.9 mm/yr [52] was estimated.…”