Palaeoseismological investigations of the Aigion Fault (Gulf of Corinth, Greece)

Pantosti, D.; Martini, P. M. De; Koukouvelas, Ioannis; Stamatopoulos, Leonidas; Palyvos, N.; Pucci, Stefano; Lemeille, Francis; Pavlides, Spyros

doi:10.1016/j.crte.2003.12.005

Cited by 54 publications

(56 citation statements)

References 14 publications

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“…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).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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International audienceThe Gulf of Corinth is one of the fastest-spreading intra-continental rifts on Earth. GPS data indicate that the rift is currently opening in a NNE-SSW direction, with a rate of extension reaching up to 16 mm yr (super - 1) in its westernmost part. Although the rest of the offshore rift has been well studied, the western tip of the rift is still poorly explored. We present an accurate map of submarine faults in this area based on two high-resolution seismic reflection surveys (single-channel sparker). In the eastern part of the studied area, the sedimentary infill is affected by the known North Eratini, South Eratini, and West Channel faults. Further to the west, the seafloor is mostly flat and is bounded to the north by the normal, south-dipping, Trizonia fault. To the north, the shallower part of the Gulf shows to the east a diffuse pattern of normal and strike-slip deformation, which is replaced to the west by a 7.5 km long SE striking strike-slip fault zone, called the Managouli fault zone. To the westernmost tip of the Gulf, in the Nafpaktos Basin, two fault sets with different strikes are encountered; the one with a NE-SW strike exhibits a clear strike-slip component. The western tip of the Gulf of Corinth is the only part of the Corinth Rift where convincing evidence for strike-slip movement has been found. This fault pattern is likely related to the complex deformation occurring at the diffuse junction at the western tip of the Rift between three crustal blocks: Continental Greece, Peloponnese, and the Ionian Island-Akarnania block

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Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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“…Onshore, trenches have been dug on the Aigion and Helike faults (Koukouvelas et al, 2001;Pantosti et al, 2004;Pavlides et al, 2004;Koukouvelas et al, 2005). They allowed an estimation of a maximum recurrence time of 360 yr for large earthquakes on the Aigion fault (Pantosti et al, 2004), and highlighted an increase in slip rate for the Helike fault during the late Holocene, associated with a cluster of four earthquakes between 1000 BCE and 0 (Koukouvelas et al, 2005).…”

Section: Physical Setting and Previous Work In Paleoseismologymentioning

confidence: 99%

Sedimentary impacts of recent moderate earthquakes from the shelves to the basin floor in the western Gulf of Corinth

et al. 2017

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a b s t r a c t a r t i c l e i n f oIn seismically active areas, long term records of large earthquakes are indispensable to constrain reccurence patterns of large earthquakes. In the western Corinth Rift, one of the most active areas in Europe in terms of seismicity, data about ancient earthquakes are still insufficient, despite historical records covering the last two millenia and several studies in onshore paleoseimology. In this paper, we test the use of offshore sediments from the Gulf of Corinth to identify sediment failures and tsunamis that have been triggered by historical earthquakes. Two shelves (40-100 m deep), one sub-basin (180 m) and the basin floor (330 m) have been sampled by short gravity cores. The cores were analyzed in order to identify and characterize event deposits. The age control has been provided by 137 Cs and 210 Pb activity measurements showing that the cores represent 2 to 4 centuries of sedimentation. In each site, sandy event deposits are interbeded in the muddy, hemipelagic sedimentation. The age of event deposits has been compared to the record of historical earthquakes using new and published macroseismic data. This comparison shows temporal coincidence of some event deposits and documented earthquakes with a macroseismic intensity ≥ VII in the area, e.g. in 1861 CE, 1888 CE and 1909 CE. In nearshore, shallow-water settings, the record of event deposits does not exactly fit with the historical record of large earthquakes because too few event deposits are present. This may be due to the absence of sediment failures or to a lower preservation of the deposits in such settings. In the deepest site, in the basin floor, the correspondence is better: a sandy turbidite probably corresponds to each large earthquake since 1850 CE, except one aseismic sediment density flow that occurred at the end of the 20th century. Surprisingly, the Ms = 6.2, June 15, 1995 Aigion earthquake is only possibly recorded in one nearshore site on the Aigion Shelf, in the form of a tsunami back-wash flow deposit. This study showed that moderate earthquakes (M 5.8-6.5) can significantly impact marine sediments. Regarding the evaluation of seismic hazard in the area, the basin floor is proposed as a promising site for long term paleoseismology in the Gulf of Corinth, while shallower settings need to be considered more carefully.

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“…Using the paleoseismological data presented by Pantosti et al (2004), it is possible to propose rates of large magnitude earthquakes on the Aigion fault (Fig. 6).…”

Section: Earthquake Rupture Rate On the Aigion Faultmentioning

confidence: 99%

“…The annual rates of M w ≥ 6 earthquakes on Aigion fault are indicated for the B14 and B14_hc models. The grey square represents the paleorate (rate of paleoearthquakes) interpreted from Pantosti et al (2004) with its uncertainties. The green box represents the rate of earthquakes greater than M w 6 on the Aigion fault inferred from the historical catalog.…”

Section: Weighting the Logic Tree Branchesmentioning

confidence: 99%

Methodology for earthquake rupture rate estimates of fault networks: example for the western Corinth rift, Greece

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Scotti

Lyon‐Caen

et al. 2017

Nat. Hazards Earth Syst. Sci.

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Abstract. Modeling the seismic potential of active faults is a fundamental step of probabilistic seismic hazard assessment (PSHA). An accurate estimation of the rate of earthquakes on the faults is necessary in order to obtain the probability of exceedance of a given ground motion. Most PSHA studies consider faults as independent structures and neglect the possibility of multiple faults or fault segments rupturing simultaneously (fault-to-fault, FtF, ruptures). The Uniform California Earthquake Rupture Forecast version 3 (UCERF-3) model takes into account this possibility by considering a system-level approach rather than an individual-fault-level approach using the geological, seismological and geodetical information to invert the earthquake rates. In many places of the world seismological and geodetical information along fault networks is often not well constrained. There is therefore a need to propose a methodology relying on geological information alone to compute earthquake rates of the faults in the network. In the proposed methodology, a simple distance criteria is used to define FtF ruptures and consider single faults or FtF ruptures as an aleatory uncertainty, similarly to UCERF-3. Rates of earthquakes on faults are then computed following two constraints: the magnitude frequency distribution (MFD) of earthquakes in the fault system as a whole must follow an a priori chosen shape and the rate of earthquakes on each fault is determined by the specific slip rate of each segment depending on the possible FtF ruptures. The modeled earthquake rates are then compared to the available independent data (geodetical, seismological and paleoseismological data) in order to weight different hypothesis explored in a logic tree.The methodology is tested on the western Corinth rift (WCR), Greece, where recent advancements have been made in the understanding of the geological slip rates of the complex network of normal faults which are accommodating the ∼ 15 mm yr −1 north-south extension. Modeling results show that geological, seismological and paleoseismological rates of earthquakes cannot be reconciled with only singlefault-rupture scenarios and require hypothesizing a large spectrum of possible FtF rupture sets. In order to fit the imposed regional Gutenberg-Richter (GR) MFD target, some of the slip along certain faults needs to be accommodated either with interseismic creep or as post-seismic processes. Furthermore, computed individual faults' MFDs differ depending on the position of each fault in the system and the possible FtF ruptures associated with the fault. Finally, a comparison of modeled earthquake rupture rates with those deduced from the regional and local earthquake catalog statistics and local paleoseismological data indicates a better fit with the FtF rupture set constructed with a distance criteria based on 5 km rather than 3 km, suggesting a high connectivity of faults in the WCR fault system.

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Palaeoseismological investigations of the Aigion Fault (Gulf of Corinth, Greece)

Cited by 54 publications

References 14 publications

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

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

Sedimentary impacts of recent moderate earthquakes from the shelves to the basin floor in the western Gulf of Corinth

Methodology for earthquake rupture rate estimates of fault networks: example for the western Corinth rift, Greece

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