Onset of Aegean-style extensional deformation in the contractional southern Dinarides documented by incipient normal fault scarps in Montenegro

. We describe two previously unreported, 5-7 km long normal fault scarps (NFS) occurring atop fault-related anticlines in the coastal ranges of the Dinarides fold-and-thrust belt in southern Montenegro, a region under predominant contraction. Both NFS show well-exposed, 6-9 m high, striated and locally polished fault surfaces in limestones, documenting active faulting during the Holocene. Sharply delimited ribbons on free rock faces show different color, varying karstification and lichen growth and suggest stepwise footwall exhumation, typical of repeated normal faulting earthquake events. 15 Displacements, surface rupture lengths and geometries of the outcropping fault planes imply paleoearthquakes with M w ≈6 ± 0.5 and slip rates of c. 0.3-0.5 mm/yr since the Last Glacial Maximum. Slip rates based on cosmogenic 36 Cl data from the scarps are significantly higher: modeling suggests 1.5 ± 0.1 mm/yr and 6-15 cm slip every c. 35-100 yrs, commencing c. 6 kyr ago. The total throw on both NFS – although poorly constrained – is estimated to max. 200 m, and offsets the basal thrust of a regionally important tectonic unit. Both NFS are incipient extensional structures that postdate growth of the fault-related 20 anticlines on top data, our study located at the transition from NE-SW-directed shortening in the northwest to NE-SW-directed extension to the southeast. the contraction ongoing Adria-Europe convergence taken up along the portions of the Dinarides, incipient extensional structures be by rollback of the Hellenic slab in the whose effects on the upper appear to be migrating along-strike the Hellenides towards the northwest. NFS evidence for a kinematic change of a thrust belt segment over time. the NFS be second-order features accommodating changes in of the underlying first-order thrust faults which they are


Introduction
Active normal faults in the Mediterranean frequently develop bedrock normal fault scarps (NFS). Their suitability as tools for 30 paleoseismic analyses has been proven by many authors (e.g., Armijo et al., 1992;McCalpin, 1996;Benedetti et al., 2002;Papanikolaou et al., 2005Papanikolaou et al., , 2013Grützner et al., 2013Grützner et al., , 2016Mason et al., 2016Mason et al., , 2017Mechernich et al., 2018). We report two previously unreported, 5-7 km long NFS along the southwestern slopes of the Rumija mountains in the coastal ranges of the Dinarides fold-and-thrust belt in southern Montenegro on the western Balkan Peninsula (Figs. 1 -4; Figs. S1 & S2, Table   S3). According to their positions between the eponymous towns, we refer to them as Bar (BFS) and Katërkolle (KFS) fault 35 scarps. Both NFS closely resemble the abundant and well-studied NFS in the Central Apennines (Italy; e.g., those ruptured during the 2016/2017 earthquake series) as well as in the Greek part of the Hellenides in terms of structural setup and length, showing evidence of segmentation and repeated co-seismic footwall exhumation during earthquakes (e.g., Papanikolaou et al., 2005, Grützner et al., 2016Mason et al., 2016;Civico et al., 2018;Mechernich et al., 2018). As the Italian and Greek examples suggest that the formation of such large-scale NFS is commonly correlated with strong extensional earthquakes, it 40 is puzzling that all known major historic earthquakes between Southern Croatia and Albania (including e.g., Montenegro 1979, Mw≈7.1, or Durrës/Albania 2019, Mw≈6.4; e.g., Benetatos and Kiratzi, 2006;Papadopoulos et al., 2020) were exclusively contractional (Fig. 1). The facts that (i) the occurrence of these newly discovered extensional structures is still fully unexplained, (ii) similar NFS in Italy and Greece are associated with major earthquakes causing many casualties and severe economic losses from destroyed medieval villages and modern infrastructure (e.g., Chiaraluce et al., 2017, Table S4) and that 45 (iii) smaller fault systems are generally underestimated in terms of their seismic hazard (Grützner et al., 2013), underline the urgent need to analyse such structures. Apart from the seismic hazard perspective, the occurrence of (possibly seismogenic) NFS in a purely contractional segment of a fold-and-thrust belt indicates a possible temporal transition in the kinematic behaviour of a mountain rangea phenomenon rarely documented in detail and calling for a geodynamic explanation.

Geological setting 50
Driver for the seismicity along the coast of Montenegro and Albania is the Adriatic microplate, whose northward motion is accompanied by a bidirectional subduction below the Balkan and Apennine peninsulas, creating almost mirror-imaged tectonic settings on both sides of the Adriatic Sea (e.g., Faccenna et al., 2014;Le Breton et al., 2017;Király et al., 2018). Both, the Apennines and Dinarides-Hellenides fold-and-thrust belts are characterized by orogen-parallel, NW-SE-striking tectonic units.
NE-SW-directed contraction along the deformation front is replaced by extensional domains in the hinterland (Fig. 1). The 55 latter is attributed to subduction-rollback, gradually migrating towards Adria in both cases (e.g., Cavinato and de Celles, 1999;Dumurdzanov et al., 2005;Carminati andDoglioni, 2012, Handy et al., 2019). Despite all similarities, seismotectonic characteristics for the concerned areas reveal major differences: In Italy, destructive earthquakes are dominantly within the hinterland extensional domain, whereas in the Dinarides-Hellenides, they are rather contractional, with epicentres close to the Montenegrin/Albanian coast (e.g., Pondrelli et al., 2006;Copley et al., 2009;Chiaraluce et al., 2017;Papadopoulos et al., 60 https://doi.org/10.5194/se-2021-97 Preprint. Discussion started: 6 August 2021 c Author(s) 2021. CC BY 4.0 License. 2020; Vittori et al., 2020;Fig. 1). Accordingly, large-scale normal faults are abundant in the extensional Apennines hinterland (e.g., Galadini and Galli, 2000), while they are less prominent in Albania (Handy et al., 2019) and so far unknown in Montenegro. We consider this view obsolete: the two newly reported NFS of Bar and Katërkolle (BFS and KFS; Figs. S1 & S2; Table S3) are not located in the hinterland away from the coast, where extensional focal mechanisms are well documented, but as close as 4 km from the coast, in a fold-and-thrust belt segment solely characterized by horizontal 65 contraction, evidenced both in the geological structures and in the predominance of reverse faulting focal mechanisms ( Fig.   1). Structurally, the BFS and KFS are located in the Budva-Cukali Unit, a regionally important tectonic nappe in the Dinarides-Hellenides consisting mainly of Mesozoic pelagic sediments topped by Paleogene synorogenic deposits (Fig. 4). In the study area, along the Rumija mountain front, only the uppermost part of its stratigraphic section appears as a c. 50 m wide corridor between the structurally underlying Dalmatian and the overlying High Karst tectonic units. Furthermore, the Budva-Cukali 70 Unit appears in remnants at the base of the High-Karst Unit in two isolated nappe outliers (Fig. 4). For more detailed information on the regional geology of the area, the reader is referred to, e.g., Biermanns et al., 2019;Schmid et al., 2020;and Schmitz et al., 2020. Current horizontal shortening rates for this region lie in the range of 3-5 mm/yr (Kotzev et al., 2008;Jouanne et al., 2012;Devoti et al., 2017), while vertical uplift rates were estimated to around 1 mm/yr (Biermanns et al., 2019 and references therein). 75

Structural and morphological mapping, site selection and fault scarp profiling
The full extent of BFS and KFS was geologically and structurally mapped to gain details of fault morphology and orientation, fault striae, surface roughness and lichen growth (Fig. 4;. Based on the mapped fault lengths (Table S9) and an 80 evaluation of horizons interpreted to display coseismic displacements per earthquake event (Figs. 3 B and S6, detailly described in section 4.1), we calculated earthquake magnitudes after Wells and Coppersmith (1994). Furthermore, four representative sites (Figs. 4 & S1; Table S3) were selected to estimate long-term (post-Last Glacial Maximum, LGM) slip rates based on topographic profiles across the fault scarps (Fig. 5, following examples of e.g., Papanikolaou et al., 2005;Mason et al., 2016) and to collect samples for 36 Cl dating (see Section 3.2). The four sites fulfil all essential requirements like minimum erosion 85 and deposition, flat scarp base, intact scarp surface and representative striations (e.g., Bubeck et al., 2015;Mechernich et al., 2018). The fault planes were cleared from vegetation (particularly for 36 Cl dating, Fig. 6), followed by a thorough structural survey including the immediate surroundings. Profiles were measured by broomstick and clinometer parallel to striations in 1m steps, c. 50 m upslope and downslope the NFS. The entire NFS height consists of two sections: (i) height of the distinct free-face and (ii) degraded NFS height, interpolated from hanging wall and footwall slope (Fig. 5). Based on these, we 90 https://doi.org/10.5194/se-2021-97 Preprint. Discussion started: 6 August 2021 c Author(s) 2021. CC BY 4.0 License. calculated two sets of post-LGM (18 ± 3 kyr) movement rates: (i) A conservative one, only considering slip on the visible freeface and (ii) a progressive one, incorporating the degraded NFS in prolongation of the free-face (Table S10) Mechernich et al., 2018). To achieve an adequate resolution for the reconstruction of long-term slip rates and seismic events, we chose a sample spacing of ca. 50 cm parallel to slip direction whilst avoiding confounding factors (e.g., joints, Fig. 6 F).
The lowermost samples were collected ca. 1 m below the scarp base by manual excavation of a trench (Fig. 6 C). These buried samples are essential to characterize pre-exposure conditions (e.g., Mechernich et al., 2018). The previously marked 15 x 5 cm sample blocks were carefully extracted with the help of an angle grinder, hammer and chisel ( Fig. 6 D-F). Subsequently 100 they were marked according to their distance from the scarp base and packed for shipping. To quantify the risk of insolation weathering at the sampling sites, exposure angles were determined in 10° steps with the help of a clinometer.

Sample preparation
Based on a spacing of 100-200 cm (striation-parallel distance on the fault plane), six sample blocks from sampling site BFSN 105 were prepared at the Institute of Geology and Mineralogy of the University of Cologne. Weathered parts and pore surroundings were carefully removed with a rotary tool before crushing and sieving. The following chemical treatment and the measurement at the CologneAMS facility were performed as described in Mechernich et al. (2018). Resulting 36 Cl/ 35 Cl, 36 Cl/ 37 Cl, and 35 Cl/ 37 Cl ratios were used to calculate the concentrations of 36 Cl and natural chlorine (Clnat). Their reliability is confirmed by the simultaneous preparation of CoCal-N 36 Cl standard material (Mechernich et al., 2019) and one blank in the respective 110 batch. The blank subtractions were 0.8-1.7 % (Tab. S11). The calculated 36 Cl concentrations of the 6 analysed samples range from ~7 × 10 4 at/g rock at 0.55 m below the scarp base to ~2 × 10 5 at/g rock at a height of 5.8 m above the scarp base. In general, the concentrations are continuously increasing with fault scarp height (Fig. 7). The natural chlorine concentrations are very low, from 6 to 17 µg/g (Tab. S11). One replicate sample was prepared and measured in Cologne (Tab. S11). An aliquot of each dissolved sample was analysed by in-house ICP-OES at the University of Cologne to determine the concentrations of 115 the principal 36 Cl target elements, Ca, K, Ti, and Fe. The ICP-OES Ca concentrations of the BFSN-samples range from 38.9% to 40.0%, indicating local variabilities (Tab. S13) with a minor impact on the 36 Cl production rate. We used one none-treated free-face sample from the BFSN site as a reference for the assumed thermal and epithermal neutron flux and thus constrain production of 36 Cl on 35 Cl. Equally, trace element analyses on these sample were used for the 36 Cl production estimate (Tab. https://doi.org/10.5194/se-2021-97 Preprint. Discussion started: 6 August 2021 c Author(s) 2021. CC BY 4.0 License. S13). Both analyses were performed by Actlabs (Canada). For the hanging wall composition, we used the soil composition of 120 the colluvium.

36 Cl scarp modelling method and parameters
To determine earthquake ages from the 36 Cl concentrations we used the Matlab® code of Schlagenhauf et al. (2010) that models synthetic 36 Cl concentrations while accounting for all influencing factors, i.e., the time-dependent variability of the fault scarp geometry, the chemical composition and the respective amount and timing of progressive exhumation. All input 125 parameters are described in the following section and in Tables S11 -S13. Several parameters have an influence on the production of cosmogenic 36 Cl, which typically extends to several meters to tens of meters below the surface. In addition to the chemical composition and density of the bedrock scarp and colluvial wedge (Tab. S12), the 36 Cl production rate depends strongly upon the rate at which the scarp is exhumed. Continuous accumulation of 36 Cl in the footwall rock occurs both in the shallow sub-surface (inherited or pre-exposure component) and to the largest part as the scarp becomes sub-aerially exposed 130 and grows higher (e.g., Schlagenhauf et al., 2010;Mechernich et al., 2018). This typically leads to increasing 36 Cl concentrations with fault scarp height, although this is somewhat complicated by erosion of the scarp free-face, whereby 36 Cl in the rock is reduced by weathering. Furthermore, production rates have to be scaled appropriately to the local and distant shielding of the site from cosmic rays and for changes of production through time due to geomagnetic field effects. In general, large offsets result in a stepwise pattern of 36 Cl concentrations (e.g., Schlagenhauf et al., 2010). For the latitude and height of 135 our study side, an offset of at least ~2 m is required. Hence, the coseismic offsets of ~5-15 cm as observed from the ribbon mapping (see section 4.1) are significantly too low to generate such stepwise 36 Cl pattern. The average density of the limestone samples was determined using the sample weight and their volume by suppression in water yielding 2.55 g/cm 3 . The density of the colluvium was estimated at ~1.5 g/cm 3 ; more specific measurements were not undertaken due to local variabilities in the clast occurrence and humidity impact. We used a 36 Cl production rate of 48.8 ± 3.4 at/g/yr from Ca-spallation (Stone et al., 140 1996) as it is derived from a similar latitude (39°N), a rather comparable altitude (1445 m a.s.l.) and integrates over a timespan of 17.3 kyr, which is appropriate for our postglacial focus. All further production rates used are given in Table S13.
Scaling with respect to latitude and elevation was performed using the Stone (2000) scaling scheme assuming a constant geomagnetic field intensity. The geometry of the fault as derived from the topographic profile (Fig. 5) is used to calculate shielding factors for the time-dependent self-shielding during the progressive exhumation of the fault plane. Thereby, 33° was 145 used for the dip of the hanging wall, 56° as dip of the fault plane, 35° as dip of the footwall and 22.2 m as the total displacement of the hillslope. An additional topographic shielding does not occur since the mountains in sight occur just insignificantly above the horizon. There is a significant local variation in the amount of weathering of the exposed fault plane, ranging from  Table S3). Ribbon abundance and widths are comparable along the full length of BFS ( Fig. S7 A & B). KFS follows the southern slopes of the Rumija mountains for >7 km and crosscuts thrusts at the base and top of the Budva-Cukali zone (Fig. 4). A connection between BFSS and KFS is conceivable, as suggested by (i) a similar mean fault plane orientation and (ii) an interjacent penetrative step in terrain steepness (Fig. S8). However, a lack of intermittent outcrops for c. 3 km along-strike and less abundant ribbons (Fig. S7 C) render such correlation less certain. Along all NFS sections, fault 175 planes reveal systematic undulations and corrugations with wavelengths up to several meters (Fig. 3 C). The trends of striations follow the mean fault plane orientation, indicating dominant dip-slip kinematics. A tendency to increasing strike-slip components away from the section centres creates patterns of radially outward-diverging striations (Fig. S5).

Slip rate and magnitude estimates derived from fault scarp profiling, surface rupture lengths and ribbons 180
Sets of conservative and progressive slip rates were calculated according to the procedures described in Section 3.1.1. The obtained conservative rates range between 0.34 ± 0.07 (site BFSS2) and 0.49 ± 0.10 (site BFSN) mm/yr. The progressive rates vary between 0.41 ± 0.08 (site BFSS2) and 1.23 ± 0.25 (site BFSN) mm/yr (Table S10) ribbons in a total of 48 sites (Fig. S11) revealed up to five horizons per location, with 15 cm average and 5-50 cm individual ribbon width. While the lower ribbons are partly correlatable over longer distances, the higher-up ones are often hardly 185 distinguishable local occurrences. The highest density of single horizons was encountered on BFSS. An average displacement of 15 cm/event on a representative free-face (e.g., at site BFSS1, ≈6.5 m high) yields an approximate average recurrence interval of ~400 yrs. Magnitude calculations after Wells and Coppersmith (1994) are based on the input parameters (ribbon widths and fault lengths) presented in Table S9. As particularly the connection between different NFS sections and NFS genesis are not trivial, we use different presumptions and calculation methods. Derived magnitudes range from Mw≈5.3 to 6.5. 190

Reliability of slip rates from fault scarp profiling 200
For our classical derivation of slip rates, we assumed that preservation of NFS initiated around the LGM, c. 18 ± 3 kyr ago in the Mediterranean region (e.g., Benedetti et al., 2002;Papanikolaou et al., 2005;Giraudi & Frezzotti,1995). Until then, periglacial conditions allowed slope degrading processes to exceed fault throw rates. Post-LGM warming, waning freeze-thaw cycles and slope stabilization by vegetation allowed fault throw to outpace slope degradation, thus forming pronounced NFS (e.g., Papanikolaou et al., 2005). Estimating slip rates using free-face heights holds two main error sources: (i) The exact timing 205 of LGM and NFS formation onset and (ii) the interpretation of NFS geometry. For our study, (i) is well-constrained by similar studies from Greece and Italy (e.g., Giraudi & Frezzotti, 1995;Kuhlemann et al., 2009;Papanikolaou et al., 2013). According to Papanikolaou et al. (2005) and references therein, the initiation of NFS formation is shifted to ages <18 ka. This and the fact that parts of the free-faces have been eroded between ~18 ka and today, make our estimates a conservative minimum. The estimation of errors connected to (ii) is more complex and related to both tectonic and erosional impacts. Unknown proportions 210 of the presently degraded fault scarps were formed both pre/syn-and post-LGM. The effect of ongoing (but reduced) erosion after formation of the NFS highly varies for different segments. The KFS and BFSS are south-(i.e., not sea-) facing and better protected by vegetation. Especially for BFSS, dissection by erosional gullies is minimal. Free-faces are steep and moderately high, degraded scarps less developed and earthquake ribbons well-visible and abundant (Fig. S7 B). By contrast, BFSN is more https://doi.org/10.5194/se-2021-97 Preprint. Discussion started: 6 August 2021 c Author(s) 2021. CC BY 4.0 License. exposed to weathering (i.e., sea-facing, surrounded by less vegetation) and dissected by numerous gullies (Figs. 3 & S1). Here, 215 more degraded scarps, high, shallowly dipping free-faces and fewer earthquake ribbons are observed (Fig S7 A). We hence consider profiling sites BFSS1 and BFSS2 to provide the most reliable results. Assuming low amounts of local post-LGM erosion at the selected sites, we favour purely free-face-based rates. A comparison with calculations including the degraded NFS (Table S10) shows that our conservative rates are, if at all, probably only exceeded by minimal amounts.

Reliability of slip rates and ages from 36 Cl dating 220
The applied forward modelling method accounts only for the analytical 36 Cl uncertainties and not for the uncertainties of the parameters introduced in Section 3.2.2 and Table S13. Changes of these input parameters would shift the modelled earthquake ages to older or younger values, without changing the relative recurrence interval (e.g., Mechernich et al., 2018). The largest effect of such a parameter change is related to the 36 Cl production rates from Ca-spallation or muon capture. A change of these two rates in the frame of published uncertainties would systematically shift all ages and slip rates within ~10%. This shift is 225 included in the age calculations but not in the slip rate calculations. Furthermore, the estimated parameters for the density of the colluvium, the erosion rate, and the apparent pre-exposure duration can cause similar shifts of the calculated ages. Changes in the erosion rate, e.g., using the minimum erosion rate of 0 mm/kyr would result in 3% younger ages at the top of the freeface compared to the used 1 mm/kyr which was chosen based on the 2-8 mm of relief at the top of the free-face. Due to the large degraded part of the fault scarp, the choice of the apparent pre-exposure duration has no impact on the restored slip 230 history of the free-face. In Section 4.2.2, we suppose a stick-slip behaviour of the NFS for the interpretation of our 36 Cl data.
The data itself would indeed leave a margin for other scenarios, e.g., a landslide/rockfall that exhumed the degraded part of the scarp ~6.5 kyr ago, followed by free-face exhumation (Fig. 7 C & D). However, this is ruled out by the fact that no indicators of landsliding were found in the hanging wall at all. Furthermore, the modelled slip rate for this scenario would be as well very high (~1.1-1.2 mm/yr), owing to the clearly increasing 36 Cl concentrations with scarp height. 235

Interpretation of ribbons, surface rupture lengths and magnitude estimation
The attribution of earthquake ribbons to individual events is highly ascertained as they are often correlatable across several locations and many of them show sharp boundaries (Figs. 3 B, S6 & S7). This excludes gradual or localized exhumation by erosion or gravitational processes and technically qualifies them as input parameters for magnitude calculations after Wells and Coppersmith (1994). Minor error sources are misinterpretations of displacement per event, as ribbons may be defaced and 240 overseen. When using fault lengths as input data for the Wells and Coppersmith (1994) method, incorrect recognition of the actual fault lengths constitutes a similar minor error source (see also Section 4.2.1; Table S9). The most severe error source, however, is the application of the empirical approach itself. For our setting with short fault lengths and relatively low magnitudes (i.e., Mw<6), Wells and Coppersmith (1994)  values would therefore advance to magnitudes in the range of the Montenegro 1979 earthquake, which are likelier to produce crustal ruptures of such scale (e.g., McCalpin, 1996).

Formation mechanisms of normal fault scarps
The position of the NFS in the hinge of thrust-related anticlines within the nappe stack of the Dalmatian Unit suggests their 250 possible origin along pre-existing planes of weakness (fold-related longitudinal fractures, e.g., Ramsay and Huber, 1983;Tavani et al., 2015 and references therein). Two hypotheses are invoked to explain the NFS in an area governed by horizontal shortening: (i) The northward-migrating boundary between foreland contraction and hinterland extension, which has increasingly migrated westward since Late Eocene (e.g., Dumurdzanov et al., 2005;Reicherter et al., 2011;Handy et al., 2019).
(ii) The activation of normal faults as second-order structures during rupture of subjacent first order thrust faults (e.g., Hicks 255 and Rietbrock, 2015), where strain is partitioned in the upper plate or hanging wall. Recent geodetic studies show that the working area lies in the frontalmost part of the deformation zone right at the tip of a north-westwards propagating line separating hinterland extension from foreland contraction (Figs. 1 & 9 B, D'Agostino et al., 2021). Gravitational collapse as a result of potential energy contrasts (sensu Copley et al., 2009) can be ruled out as striations, although diverging outward, are relatively consistent with respect to the undulating but otherwise planar fault planes. 260 Furthermore, the existence of the described NFS has implications on observed GPS-derived convergence rates: The fault slip rate of 1.5 mm/yr along the normal fault plane with a dip of 60° results in a horizontal extension of 0.75 mm/yr. In order to achieve the geodetically observed convergence of 3-4 mm/yr, the actual convergence must therefore be 3.75-4.75 mm/yr ( Fig.   9 D). The accommodation of the total convergence in the coastal area ( Fig. 9 C) and the lack of instrumentally recorded extensional earthquakes are strongly supportive of scenario (ii). This is further substantiated by the existence of other recent 265 geomorphological features in the study area such as dry valleys and deflected river channels, which indicate a still predominantly contractional regime (Fig. 10, Biermanns et al., 2019;Schmitz et al., 2020).

Conclusion
We report two previously unknown, active normal faults with well-preserved bedrock NFS along the contractional front of the southern Dinarides fold and thrust-belt. We propose a tectonic, co-seismic origin of these structures. Relations between fault 270 orientation, striations, earthquake ribbons and surrounding structures suggest that the normal faults are either the result of rollback-induced westward migrating extensional tectonics or more likely second-order features linked to subjacent, higherorder thrusts, capable of triggering earthquakes up to Mw≈7±0.5. Maximum magnitudes on the NFS are expected to reach Mw≈6±0.5. Long-term fault slip rates were estimated from free-face height and height of the degraded scarp, assuming a post- LGM age (≤18 kyr) of the NFS. Minimum slip-rates based on four selected sites amount to 0.34 ± 0.1 -0.49 ± 0.1 mm/yr and 275 recurrence intervals for major earthquakes are in the range of ≤400 yrs. Although site selection has a large effect on final estimates, these values appear realistic against the backdrop of available GPS rates and common earthquake magnitudes in the region. The normal faults are exactly located above the "blind" thrust fault and epicentre that was responsible for the Mw 7.1 https://doi.org/10.5194/se-2021-97 Preprint. Discussion started: 6 August 2021 c Author(s) 2021. CC BY 4.0 License.      Fig. 4 for locations). Slip rates are derived from the here presented free-face heights and heights including the degraded scarp (compare Table S10, two right columns). Stereoplots show fault plane orientations (great circles) and striations (triangles) within ± 5 m of the study site. Sites are indicated in Fig. 4; sites BFSN and BFSS