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Normal fault growth over different timescales. (a) Schematic block diagram showing the range and basin topography and active fault scarp, together with measurements of Quaternary vertical displacement measured from bedrock and range height. (b) Schematic graph showing displacement accumulation on geological (Quaternary) timescales (thick black line) with the open circle showing the cumulative displacement indicated in the block diagram. Thick dashed line shows average displacement accumulation for the duration of faulting at a rate of 0.5 mm/year. Displacement curve in the box is shown in “c.” (c) Schematic graph showing the accumulation of fault displacement (thick black line) in five earthquakes (labeled EQ1–5). SED in individual earthquakes is indicated by the height of the vertical sections of the curve, while recurrence intervals are defined by the lengths of the horizontal sections of the curve. Thick dashed line shows average displacement accumulation for the duration of faulting at a rate of 0.5 mm/year, while the thick gray line shows the range of displacement rates averaged for two earthquake cycles. SED, single event maximum displacement.
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Active normal faults on the Mediterranean island of Crete form prominent limestone scarps together with basin and range topography. These faults mainly strike E‐ESE and N‐NNE in southern and northern Crete, respectively, with fault sets commonly intersecting and northerly‐trending faults being a factor of three more abundant. Lengths, displacements...
Citations
... The aforementioned pattern of compressional and transcurrent deformation is superimposed by widespread extension due to slab rollback of the subducting Nubian plate in the south and the propagation of the NAF into the Aegean in the north (Rodriguez et al., 2023;Schlidgen et al., 2014). As a result, multidirectional normal faulting prevails across continental Greece, Peloponnese, Crete and the entire northern and eastern Aegean (Armijo et al., 1992;Chatzipetros et al., 2013;Nicol et al., 2020;Papanikolaou et al., 2002). Complex faulting patterns within the Aegean upper plate indicate that strain is not only currently accommodated by the well-defined larger structures but also by secondary structures which are traversing the Aegean crust onshore and offshore Greece. ...
... Finally, as regards Crete, the most striking feature of the strain rate field is the prevalence of active ∼N-S extension at the southern part of the island. Nicol et al. (2020) have highlighted a spatial separation of the orientation of normal faulting on Crete, with E-W trending faults extending mostly along the southern coastline, in agreement with our strain rate field. The peak values are resolved at the Messara Basin (MeB in Figure 1), a graben which is controlled by E-W and ENE-WSW trending faults that are still active today (Caputo et al., 2010;Nicol et al., 2020), as it is confirmed by the recent M w 4.7 event (18 May 2023) whose calculated moment tensors are consistent with E-W-striking extensional faulting (European-Mediterranean Seismological Center, https:// www.emsc-csem.org/Earthquake/tensors.php). ...
... Nicol et al. (2020) have highlighted a spatial separation of the orientation of normal faulting on Crete, with E-W trending faults extending mostly along the southern coastline, in agreement with our strain rate field. The peak values are resolved at the Messara Basin (MeB in Figure 1), a graben which is controlled by E-W and ENE-WSW trending faults that are still active today (Caputo et al., 2010;Nicol et al., 2020), as it is confirmed by the recent M w 4.7 event (18 May 2023) whose calculated moment tensors are consistent with E-W-striking extensional faulting (European-Mediterranean Seismological Center, https:// www.emsc-csem.org/Earthquake/tensors.php). Westwards and eastwards of the Messara Basin, extension decreases and slightly rotates counterclockwise to become NW-SE. ...
We present a new geodetic strain rate and rotation rate model for Greece that has been derived using a highly dense GPS velocity field. The spatial distribution and the resolved rates of the various velocity gradient tensor quantities provided updated constraints on the present‐day upper crustal deformation in the region and revealed new details not reported previously. The spatial distribution of the second invariant demonstrated that the overall magnitude of strain rates is highest across two well‐defined provinces. The first follows the North Anatolian Fault and its two branches within the north Aegean, crosses central Greece and through the Gulf of Corinth it terminates in western Greece, while the second encompasses the extensional province of western Turkey and the eastern Aegean Sea islands. Our estimates revealed that shearing affects some of the fault‐bounded grabens of central Greece that lie to the SW of the North Aegean Basin implying considerable oblique extension. We identified a narrow region of counterclockwise rotation whose location and kinematics have been induced by the net effect across the intersection of the clockwise rotating domains of western and central Greece. The Aegean microplate and the Anatolian plate are separated by a wide transition zone which accommodates the curved stretching of the entire plate system. In both edges of the Hellenic forearc the dominant mode of crustal strain is E‐W extension. We found that earthquakes of M ≥ 5.6 are spatially well‐correlated with high‐strain areas, indicating that strain rate mapping could be used to inform future probabilistic seismic hazard analyses.
... These two studies did not simulate subduction and show that, amongst other faults, large-scale normal faults formed close to the trench with a strike that is perpendicular with respect to the strike of the trench and volcanic arc. However, in the Aegean domain, oblique extensional faults along the Hellenic arc-which formed as late as the Pliocene (Angelier et al., 1982;Armijo et al., 1996;Nicol et al., 2020) and generally have a small offset-mostly have an oblique strike rather than a perpendicular strike with respect to the Hellenic Trench, Pliny Trench, volcanic arc, and slab isodepth contour lines (Fig. 1). ...
... This allows us to directly compare the overriding plate Papazachos et al., 2000). Locations of normal faults, detachment faults, and extensional basins were compiled from Armijo et al. (1996), Caputo et al. (2010), Jolivet et al. (2013Jolivet et al. ( , 2021, Brun et al. (2016), and Nicol et al. (2020). Red faults represent the ~N-S striking oblique-slip normal faults that (re)activated since the Pliocene in the forearc domain. ...
... These faults are also oriented obliquely with respect to the magmatic arc, and additionally, oriented at an oblique angle with measured GPS velocity vectors (Fig. 13b). The faults formed during the Pliocene and are steeply dipping (60-85 • ) (Armijo et al., 1996;Caputo et al., 2010;Jolivet et al., 2013;Nicol et al., 2020). Several N-S striking faults on Crete demonstrate two superimposed generations of slickenlines, where the older generation is oblique-slip and the Fig. 13. ...
... Tectonic blocks separated along the Spili fault, indicating both arc-parallel and arc-normal extension [69,70]. In the Holocene, Crete transitioned from uplift to subsidence [71][72][73]. ...
This paper explores an innovative educational program designed to protect and promote the geocultural heritage of Minoan Crete. The program applies environmental education and sustainability principles while integrating theater in education, a novel approach that significantly impacts participants’ perspectives. By effectively combining these elements, the program fosters environmental awareness, deepens cultural appreciation, and instills sustainable behaviors in both the local population and visitors. This interdisciplinary approach, blending geocultural heritage into environmental education, promotes an understanding of the delicate balance between nature and human interaction during the Minoan era. The paper also examines the program’s potential for broader community engagement and policy influence, emphasizing how its educational outcomes could result in meaningful changes at both community and policy levels. We advocate for the preservation of Minoan Crete’s geocultural heritage and its sustainable future through a unique blend of educational strategies, marking a milestone in heritage conservation.
... Fault displacement rates are sensitive to the time-period of observation, and this should be considered in our modeling, since the throw-rates we use to calculate yearly rates of interseismic stress loading for the Calabria faults are measured over a wide range of time periods (15-700 ka, see Section 3.2). Although displacement rates are relatively uniform on long temporal scales (>300 ka), over short time periods (<20 ka) they can vary greatly, by up to three orders of magnitude Nicol et al., 2009Nicol et al., , 2020. However, for the study area, the agreement between geological rates and those measured with GPS geodesy and seismic moment release rate (e.g., Cowie et al., 2013;D'Agostino et al., 2011;Meschis et al., 2022;Serpelloni et al., 2005Serpelloni et al., , 2010, suggests that the geological observation periods may well be long enough to be compatible with the long-term average for elastic deformation rates and hence stress loading rates. ...
We model Coulomb stress transfer (CST) due to 30 strong earthquakes occurring on normal faults since 1509 CE in Calabria, Italy, including the influence of interseismic loading, and compare the results to existing studies of stress interaction from the Central and Southern Apennines, Italy. The three normal fault systems have different geometries and long‐term slip‐rates. We investigate the extent to which stress transfer can influence the occurrence of future earthquakes and what factors may govern the variability in earthquake recurrence in different fault systems. The Calabrian, Central Apennines, and Southern Apennines fault systems have 91%, 73%, and 70% of faults with mean positive cumulative CST in the time considered; this is due to fewer faults across strike, more across strike stress reductions, and greater along‐strike spacing in the three regions respectively. In regions with close along strike spacing or few faults across strike, such as Calabria and Southern Apennines, the stress loading history is mostly dominated by interseismic loading and most faults are positively stressed before an earthquake occur on them (96% of all faults that ruptured in Calabria; 94% of faults in Southern Apennines), and some of the strongest earthquakes occur on faults with the highest mean cumulative stress of all faults prior to the earthquake. In the Central Apennines, where across strike interactions are the predominant process, 79% of earthquakes occur on faults positively stressed. The results highlight that fault system geometry plays a central role in characterizing the stress evolution associated with earthquake recurrence.
... (b) Simplified velocity field for Greece (using Nocquet, 2012). (c) Map of Crete and simplified upper crustal fault map (Robertson et al., 2019;Nicol et al., 2020), Ph: Phalasarna fault, WC: Western Crete fault; Pt: Ptolemy fault. Dashed faults are postulated and discussed herein. ...
... Offshore, a combination of subduction-related convergence occurs at depths below ~15 km whilst extensional/transtensional faulting dominates above ~15 km (Papazachos, 1990;Papazachos et al., 2000;Ten Veen and Kleinspehn, 2003;Meier et al., 2004;Alves et al., 2007;Tsimi et al., 2007;Kokinou et al., 2012;Sakellariou and Tsampouraki-Kraounaki, 2019). Onshore, arc normal and arc parallel extension dominates (Mercier et al., 1989;Taymaz et al., 1990;Armijo et al., 1992;Ten Veen and Meijer, 1998;Ten Veen and Kleinspehn, 2003;Caputo et al., 2010;Zygouri et al., 2016;Ganas et al., 2017) (Fig. 1c) evidenced by E-W, NE-SW and NW-SE trending faults that have been active throughout the Holocene and the Late Pleistocene (e.g., Armijo et al., 1992;Caputo et al., 2010;Ott et al., 2019;Robertson et al., 2019;Nicol et al., 2020;Mechernich et al., 2022;Ganas et al., 2022). In places along the eastern, southern, and western Cretan coastlines, extensional faults that strike parallel to the coastlines downthrow marine terraces in their hangingwalls (Skourtsos et al., 2007;Tsimi et al., 2007;Gaki Papanastassiou et al., 2009;Caputo et al., 2010;Ott et al., 2019;Robertson et al., 2019, Fig. 1c). ...
... However, global D max -L max datasets show a high degree of scatter (e.g., Rotevatn et al., 2019), which may reflect, for example, differences in the geological setting within which the studied fault network formed, or uncertainties in measuring the key geometric parameters due to seismic imaging quality or outcrop extent (e.g., Walsh and Watterson, 1988;Gillespie et al., 1992;Kim and Sanderson, 2005). An alternative interpretation is that this variability results from fault maturity, related to the fact that some faults may attain their near-final lengths before accumulating significant displacement (i.e., the latter, constant-length fault model; e.g., Walsh et al., 2002;Meyer et al., 2002;Nicol et al., 2005Nicol et al., , 2016Childs et al., 2017;Rotevatn et al., 2019;Nicol et al., 2020;Lathrop et al., 2022). Different definitions of fault maturity exist in the literature. ...
... Specifically, if the faults grew in accordance with the propagating fault model, the ratio between lateral propagation and displacement rate will be closer to 1. However, if the faults established their lengths before accruing significant displacement, then the ratio between lateral propagation and displacement would be >1, especially during the early stages of fault development (i.e., initial 20 -30% of fault lifespan; e.g., Walsh et al., 2002;Meyer et al., 2002;Nicol et al., 2005Nicol et al., , 2016Childs et al., 2017;Rotevatn et al., 2019;Nicol et al., 2020;Lathrop et al., 2022) . We observe that independent of fault length and whether the duration of faulting is estimated to be 6.2 or 3.1 Myr, the studied faults propagated laterally much more rapidly (i.e., c. 300-20 times faster) than they accumulated displacement ( Figure 10C). ...
... Our slip rate data compilation builds on previous works (e.g., Nicol et al., 2005;Mouslopoulou et al., 2009;Nicol et al., 2020) and includes lateral propagation and displacement rate data measured over a range of temporal scales using different methods (geodetic, GPS, field observations, seismic refraction, and reflection data). By compiling the database, we note that lateral propagation rates are often not reported or less frequently documented compared to displacement rates. ...
Observations of how faults lengthen and accrue displacement during the very earliest stages of their growth are limited, reflecting the fact that the early syn-kinematic sediments that record this growth are often deeply buried and difficult to image with geophysical data. Here, we use borehole and high-quality 3D seismic reflection data from SW Barents Sea, offshore Norway to quantify the lateral propagation (c. 0.38 – 3.4 mm/year) and displacement accumulation (c. 0.0062 – 0.025 mm/year) rates (averaged over 6.2 Myr) for several long (up to 43 km), moderate displacement (up to 155 m), syn-kinematic faults that we argue provide a unique, essentially ‘fossilised’ snapshot of the earliest stage of fault growth. We show that lateral propagation rates were up to 300 times faster than displacement rates during the initial ~25% of fault lifespan, suggesting that these faults lengthened much more rapidly than they accrued displacement. Our inference of rapid lengthening is also supported by geometric observations including: (i) low Dmax/Lmax (<0.01) scaling relationships, ii) high (>5) length/height aspect ratios, iii) broad, bell-shaped throw-length profiles, and iv) hangingwall depocenters forming during deposition of the first seismically detectable stratigraphic unit spanning the length of the fault. We suggest that the high ratio between lateral propagation rate and displacement rate is likely due to relative immaturity of the studied fault system, an interpretation that supports the ‘constant-length’ fault growth model. Our results highlight the need to document both displacement and lateral propagation rates to further our understanding of how faults evolve across various temporal and spatial scales.
... (normal faults(Nicol et al., 2020), with the Spili Fault highlighted yellow. The location of Crete is indicated in the inset map. ...
The fluctuations of the Rare Earth Elements and Yttrium (REE-Y) concentrations on exhumed carbonate normal fault scarps may reveal the number and size of paleoearthquakes that exposed the scarp subaerially. This is because, prior to each large-magnitude earthquake, narrow (<50 cm) sections of the fault plane which are in
direct contact with the soil become enriched in REE-Y before they are exhumed co-seismically, together with deeper, non-enriched, scarp sections. Following exhumation, depletion in REE-Y commences on both the enriched (i.e. ‘soil rupture zone’) and non-enriched (i.e. ‘rock rupture zone’) scarp sections. Although these processes are commonly described to occur on carbonate scarps, the mechanisms through which they operate remains poorly understood. Here, we present a series of laboratory tests that mimic the natural process of REE-Y enrichment/depletion to elucidate the mechanism of REE-Y impregnation. Our results indicate a fast uptake of REE-Y by the carbonate plane, when in contact with soil, either as (REE, Y)2(CO3)3 precipitate or by adsorption on calcite surfaces. The source of REE-Y in soil solution is released in a “pulses” due to alternations of dry and wet periods, characteristic of Mediterranean climatic conditions. Organic matter oxidation during the first rain
events, triggers the Mn reductive dissolution and the release of REE-Y into the soil solution. The pH decrease due to organic matter dissolution is buffered by calcite, especially in the vicinity of the scarp, where calcite dissolution and re-precipitation occurs with a marked pH oscillation between 9.3 and 7.7. Further, comparison of
these results with empirical data from three co-seismically exhumed fault scarps in Greece and Italy places quantitative constraints on the timing of these processes: the REE-Y enrichment within the ‘soil rupture zone’ may reach a maximum of ~50% in about 500 years (+0.53 μg/kg/year), while the REE-Y depletion from the scarp is
slow (-0.021 μg/kg/year), with a maximum recorded retention time of ~16 ka. These enrichment and depletion characteristics work together to preserve paleoearthquake signal on carbonate scarps. Thus, this methodology is a valuable tool for quantifying the number of past earthquakes on carbonate fault scarps and allows more targeted use of expensive dating techniques (i.e. with cosmogenic nuclides) in order to derive the precise timing of these paleoearthquakes.
... Constraints from mapping and geophysical data indicate that the VF has a trace length of 100 km and a maximum displacement of around 5 km (Bartrina et al., 1992;Gallart et al., 1997;Gaspar-Final Discussions and Conclusions Escribano et al., 2004;Gómez & Guimerà, 1999;Juez-Larré & Andriessen, 2006;Roca et al., 1999;Sàbat et al., 1995;Vidal et al., 1995), scaling properties that are consistent with existing empirical constraints for normal fault (Nicol et al., 2020). The main fault dips, from geophysical and borehole results, are quite consistent, between 60º and 70º. ...
... Within the study area, Miocene syn-rift sediments are no greater than ca 1.25 km thick, a scenario which is attributed to an eastward decrease in displacement along the fault, with previous work indicating a fault tip and the end of the V-P hangingwall basin a further 25 km to the east (Fig. 1). Regional maps support the discontinuous nature of the V-P Fault and its hangingwall basin, with an overall mapped length of ca 120 km and a maximum displacement of 5 km (accounting for fault dip), scaling properties which are consistent with previously published normal fault databases (e.g., Nicol et al. 2020). ...
... Constraints from mapping and geophysical data indicate that the V-P Fault has a maximum displacement of ca 5 km and a trace length of 100 km (Bartrina et al., 1992;Gallart et al., 1997;Gaspar-Escribano et al., 2004;Gómez and Guimerà, 1999;Juez-Larré and Andriessen, 2006;Roca and Guimerà, 1992;Roca et al., 1999;Sàbat et al., 1995;Vidal et al., 1995), scaling properties that are consistent with existing empirical constraints for normal faults (Nicol et al. 2020). ...
... Lineaments mappable on 5 m DEM within the epicentral area are commonly represented in the field by active faults. The normal faults presented here are classified according to their relative activity as "active faults with Holocene scarps" and "active faults with pre-Holocene scarps," broadly following the classification provided by Nicol et al. (2020) and Faure Walker et al. (2021). Direct dating of offset Holocene deposits is available only for 4 faults in Thessaly (RF, GF, TF, and Domokos-Ekkara Fault; Caputo & Helly, 2005;Caputo et al., 2004;Palyvos et al., 2010;Tsodoulos et al., 2016), three of which lie in the immediate vicinity of the epicenter (see magenta lines in Figure 3). ...
Large magnitude (Mw ∼ ≥6) earthquakes in extensional settings are often associated with simultaneous rupture of multiple normal faults as a result of static and/or dynamic stress transfer. Here, we report details of the coseismic breaching of a previously unrecognized large‐scale fault relay zone in central Greece, through three successive normal fault earthquakes of moderate magnitude (Mw 5.7–6.3) that occurred over a period of ∼10 days in March 2021. Specifically, joint analysis of InSAR, GNSS and seismological data, coupled with detailed field and digital fault mapping, reveals that the Tyrnavos Earthquake Sequence (TES) was accommodated at the northern end of a ∼100 km wide transfer structure, by faults largely unbroken during the Holocene. By contrast, the southern section of this relay zone appears to have accrued significant slip during Holocene. InSAR‐derived displacements agree with the loci of eight subtle, previously undetected, faults that accommodated coseismic and/or syn‐seismic normal fault slip during the TES. Kinematic modeling coupled with fault mapping suggests that all involved faults are interconnected at depth, with their conjugate fault‐intersections acting largely as barriers to coseismic rupture propagation. We also find that the TES mainshocks were characterized by unusually high (>6 MPa) stress‐drop values that scale inversely with rupture length and earthquake magnitude. These findings, collectively suggest that the TES propagated north‐westward to rupture increasingly stronger asperities at fault intersections, transferring slip between the tips of a well‐established, but previously unrecognized, relay structure. Fault relay zones may be prone to high stress‐drop earthquakes and associated elevated seismic hazard.
... The modeled D-L relationships show significant scatter (over 2-3 orders of magnitude) throughout each model timestep, similar to magnitudes observed from ancient and active fault D-L studies. The scatter may be attributed to the process of fault growth, rather than measurement errors or variation in mechanical properties (Cartwright et al., 1995;Pan et al., 2022), and may reflect how individual earthquakes accumulate displacement over intermediate (10 3 -10 6 yr) timescales Nicol et al., 2009Nicol et al., , 2010Nicol et al., , 2020. ...
Continental extension is accommodated by the development of kilometer‐scale normal faults, which grow during meter‐scale slip events that occur over millions of years. However, reconstructing the entire lifespan of a fault remains challenging due to a lack of observational data with spatiotemporal scales that span the early stage (<10⁶ yrs) of fault growth. Using three‐dimensional numerical simulations of continental extension and novel methods for extracting the locations of faults, we quantitatively examine the key factors controlling the growth of rift‐scale fault networks over 10⁴–10⁶ yrs. Early formed faults (<100 kyrs from initiation) exhibit scaling ratios consistent with those characterizing individual earthquake ruptures, before evolving to be geometrically and kinematically similar to more mature structures developed in natural fault networks. Whereas finite fault lengths are rapidly established (<100 kyrs), active deformation is transient, migrating both along‐ and across‐strike. Competing stress interactions determine the distribution of active strain, which oscillates between being distributed and localized. Higher rates of extension (10 mm yr⁻¹) lead to more prominent stress redistributions through time, promoting episodic localized slip events. Our findings demonstrate that normal fault growth and the related occurrence of cumulative slip is more complex than that currently inferred from displacement patterns on now‐inactive structures, which only provide a space‐ and time‐averaged picture of fault kinematics and related seismic hazard.
