Irene Puliti
email: irene.puliti@unich.it

Alberto Pizzi

Lucilla Benedetti

Alessandra Di Domenica

Jules Fleury

Comparing Slip Distribution of an Active Fault System at Various Timescales: Insights for the Evolution of the Mt. Vettore-Mt. Bove Fault System in Central Apennines

come

Introduction

Long-term fault escarpments are built by the addition of incremental earthquakes and thus contain key information on earthquake rupture processes, where the rupture stopped and where it has propagated during those past events. Several studies have proposed that earthquake ruptures may be arrested by structural and/or geometrical complexities, such as fault intersections and step-overs, [START_REF] Wesnousky | Seismological and structural evolution of strike-slip faults[END_REF], Bejar-Pizarro et al. 2013;[START_REF] Klinger | Slip rate on the Dead Sea transform fault in northern Araba valley (Jordan)[END_REF]. Constraining the spatial extent of a coseismic rupture (e.g., where it may be arrested during an earthquake), is fundamental for deriving the expected earthquake magnitude, essential for seismic design and population preparedness.

However, few datasets exist to unravel whether the segmentation seen in coseismic ruptures is characteristic through time and, if yes, over which time scales. The seismic sequence that occurred in 2016 in Central Italy represents a great chance to observe and understand how a normal fault system evolves because the detailed pattern of the 2016 coseismic throw can be compared to the cumulative displacements that can be constrained from geological and geomorphological analysis.

This sequence has been characterized by three spatially and temporally clustered mainshocks that are localized within a 25 km-long area that is oriented NNW-SSE (the active Mt. Vettore-Mt. Bove fault system, VBFS): 24 August, Mw 6.0; 26 October, Mw 5.9; and 30 October, Mw 6.5 (Civico et al., 2018, Villani et al., 2018a). The surface faulting that is associated with the 30 October earthquake (maximum dip-slip displacement of ∼2 m; Villani et al., 2018a) is one of the clearest and most spectacular coseismic ruptures that have been observed after an earthquake in the Tectonics Mediterranean area in recent decades. The coseismic slip, however, is complex and is distributed within several rupturing segments. How the rupture propagated through these various segments and what role inherited structures plays in this complex pattern are still debated (see [START_REF] Porreca | 3D geological reconstruction of the M. Vettore seismogenic fault system (Central Apennines, Italy): Cross-cutting relationship with the M. Sibillini thrust[END_REF] for a complete discussion and references therein). In particular, several models have been proposed that emphasize the presence and the role of structural barriers at depth in the rupture propagation and arrest (e.g., [START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF]Chiarabba et al., 2018;[START_REF] Falcucci | The Campotosto seismic gap in between the 2009 and 2016-2017 seismic sequences of central Italy and the role of inherited lithospheric faults in regional seismotectonic settings[END_REF][START_REF] Lavecchia | Ground deformation and source geometry of the 24 August 2016 Amatrice earthquake (Central Italy) investigated through analytical and numerical modeling of DInSAR measurements and structural-geological data[END_REF][START_REF] Pizzi | Fault Segmentation as Constraint to the Occurrence of the Main Shocks of the 2016 Central Italy Seismic Sequence[END_REF][START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF][START_REF] Walters | Dual control of fault intersections on stop-start rupture in the 2016 Central Italy seismic sequence[END_REF].

Here we provide a set of data of the surface fault displacement at different time scales allowing to discuss the temporal and spatial evolution of this active normal fault system. We investigated the entire VBFS displacement at three different time scales, hereafter referred to as: "long-term", (~ 1 Myr); i.e. based on the geological slip accumulation during Quaternary extension; "mid-term" (~ last 18 kyr), i.e. derived from geomorphic evidence of faulting following the Last Glacial Maximum (see further explanation in section 3); "short-term", during an instantaneous seismic event. Iezzi et al., (2018), [START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF] and [START_REF] Porreca | 3D geological reconstruction of the M. Vettore seismogenic fault system (Central Apennines, Italy): Cross-cutting relationship with the M. Sibillini thrust[END_REF] have also compared the geological and the co-seismic displacement but focusing on the Mt Vettore fault.

We compared the 2016 coseismic slip distribution along the entire VBFS system with morphological and geological throws (i.e., vertical-displacement component) from topographic profiles, cross-sections, geological horizons, and field surveys. Our results can better constrain how a normal fault system evolves in the short-, mid-and long-term and how its evolution is influenced by fault segmentation and structural barriers. We also investigate the link between surface observations and structures at depth.

Seismotectonics of the area

Regional geological framework

The Apennine chain is an NE-verging imbricate fold-and-thrust belt that developed from the Oligocene along the margin of the Adriatic microplate [START_REF] Carminati | Alps vs. Apennines: The paradigm of a tectonically asymmetric Earth[END_REF][START_REF] Patacca | Structural architecture of the central Apennines: Interpretation of the CROP 11 seismic profile from the Adriatic coast to the orographic divide[END_REF] Tectonics 2008 and reference therein). The chain is now experiencing post-orogenic ENE-oriented Quaternary extension [START_REF] Barchi | Sintesi delle conoscenze sulle faglie attive in Italia Centrale: parametrizzazione ai fini della caratterizzazione della pericolosità sismica[END_REF][START_REF] Calamita | Recent and active extensional tectonics in the southern Umbro-Marchean Apennines (Central Italy)[END_REF][START_REF] Galadini | Active Tectonics in the Central Apennines (Italy) -Input Data for Seismic Hazard Assessment[END_REF][START_REF] Lavecchia | Seismotectonic zoning in east-central Italy deduced from an analysis of the Neogene to present deformations and related stress fields[END_REF][START_REF] Pizzi | Quaternary normal faults, intramontane basins and seismicity in the Umbria-Marche-Abruzzi Apennine Ridge (Italy): Tectonics contribution of neotectonic analysis to seismic hazard assessment[END_REF] with regional extension rates of 3-4 mm/yr [START_REF] D'agostino | Active tectonics of the Adriatic region from GPS and earthquake slip vectors[END_REF][START_REF] Walker | Horizontal strain-rates and throw-rates across breached relay zones, central Italy: Implications for the preservation of throw deficits at points of normal fault linkage[END_REF] related to the relative motion between the Adriatic microplate and the Tyrrhenian coastal region [START_REF] D'agostino | Evidence for localized active extension in the central Apennines (Italy) from global positioning system observations[END_REF][START_REF] D'agostino | Complete seismic release of tectonic strain and earthquake recurrence in the Apennines (Italy)[END_REF][START_REF] Devoti | A combined velocity field of the Mediterranean region[END_REF]. In the study area, the main structure of the chain is represented by the Olevano-Antrodoco-Sibillini (OAS) thrust, an arc-shaped thrust front that strikes NW to the north and NNE to the south with respect to the Mt. Vettore pivot, or obliquely to the NNW-SSE-trending Quaternary normal fault systems (Figure 1). The OAS thrust affects Mesozoic-Tertiary sedimentary successions that are characterized by platform-to-basinal limestones, marly limestones, and marls and Messinian turbidite siliciclastic deposits by superposing the carbonate units over the Messinian deposits of the Laga Fm (Figure 2.a; [START_REF] Calamita | The arcuate shape of the Umbria-Marche-Sabina Apennines (central Italy)[END_REF][START_REF] Mazzoli | Geometry, segmentation pattern and displacement variations along a major Apennine thrust zone, central Italy[END_REF][START_REF] Pierantoni | Stratigraphic and structural features of the Sibillini mountains (Umbria-Marche Apennines, Italy)[END_REF].

The location and orientation of the OAS thrust seem to have been strongly controlled by a preexisting Early Jurassic normal-fault zone: the NNE-SSW Ancona-Anzio lineament. This lineament has been interpreted as a high-angle fault zone that is approximately one hundred kilometers long and acted during the Mesozoic-Early Tertiary as a syn-sedimentary extensional fault system (Castellarin et al., 1982;[START_REF] Parotto | Geological summary of the Central Apennines[END_REF]. This fault separated the Umbria-Marche pelagic domains to the west from the Lazio-Abruzzi carbonate platform domain to the east [START_REF] Castellarin | Fasi distensive, trascorrenze e sovrascorrimenti lungo la" Linea Ancona-Anzio[END_REF]. During the Neogene, this regional paleogeographic boundary experienced positive inversion through a fold-and-thrust belt contractional phase, which worked as an oblique high-angle thrust ramp (e.g., [START_REF] Calamita | Contrasting styles of fault reactivation in curved orogenic belts: Examples from the Central Apennines (Italy)[END_REF]2012;[START_REF] Lavecchia | Il sovrascorrimento dei Monti Sibillini; analisi cinematica e strutturale[END_REF][START_REF] Tectonics Tavarnelli | Implications of fault reactivation and structural inheritance in the Cenozoic tectonic evolution of Italy[END_REF].

On the other hand, the shallower portion of the OAS thrust surface, i.e., the first 2-3 km, shows low-angle geometry and is locally folded by NW-SE-/NNW-SSE-trending anticlines that developed in its footwall [START_REF] Alberti | Modes of propagation of the compressional deformation in the Umbria-Marche Apennines[END_REF][START_REF] Di Domenica | Relationships between thrusts and normal faults in curved belts: New insight in the inversion tectonics of the Central-Northern Apennines (Italy)[END_REF][START_REF] Porreca | Seismic reflection profiles and subsurface geology of the area interested by the 2016-2017 earthquake sequence (Central Italy)[END_REF].

In recent decades, several authors suggested that the OAS thrust could represent an oblique structural barrier to the growth and associated seismicity of active Quaternary seismogenic extensional faults [START_REF] Pizzi | Pre-existing cross-structures and active fault segmentation in the northern-central Apennines (Italy)[END_REF][START_REF] Di Domenica | Relationships between thrusts and normal faults in curved belts: New insight in the inversion tectonics of the Central-Northern Apennines (Italy)[END_REF]. Evidence consistent with this idea was presented by the spatial and temporal evolution of the 2016 seismic sequence, where the OAS played a major role in the slip propagation rupture halting, or in fault slip accommodating extension (e.g. [START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF][START_REF] Pizzi | Fault Segmentation as Constraint to the Occurrence of the Main Shocks of the 2016 Central Italy Seismic Sequence[END_REF][START_REF] Walters | Dual control of fault intersections on stop-start rupture in the 2016 Central Italy seismic sequence[END_REF].

Additionally, the structural setting of the area is complicated by the presence of other pre-, syn-and post-thrusting normal faults from different extensional phases that are widely recognized in the Apennines, such as the Neogene normal faulting occurred alongside crustal and lithospheric foreland flexural processes, influencing the deposition of foredeep sequences [START_REF] Tavani | A review of deformation pattern templates in foreland basin systems and fold-and-thrust belts: Implications for the state of stress in the frontal regions of thrust wedges[END_REF][START_REF] Tavarnelli | From extension to contraction in syn-orogenic foredeep basins: the Contessa section, Umbria-Marche Apennines, Italy[END_REF]. Those faults experienced a Neogene positive inversion with the compressional phase and, then, a negative inversion during the Quaternary (e.g. Di Domenica et al., 2012 and reference therein). The Quaternary normal faults overprinted the Neogene contractional structures (e.g., [START_REF] Calamita | Recent and active extensional tectonics in the southern Umbro-Marchean Apennines (Central Italy)[END_REF][START_REF] Lavecchia | Seismotectonic zoning in east-central Italy deduced from an analysis of the Neogene to present deformations and related stress fields[END_REF][START_REF] Galadini | Active Tectonics in the Central Apennines (Italy) -Input Data for Seismic Hazard Assessment[END_REF], since at least the Early Pleistocene (1.1-1.2 Ma according to [START_REF] Blumetti | Il Pleistocene inferiore nell'area nursina[END_REF]Coltorti et al., 1998;Calamita et al., 1999).

Monte Vettore -Monte Bove fault system

The Mt. Vettore-Mt. Bove normal fault system (VBFS), which was responsible for the 2016 Central Italy seismic sequence, represents one of the easternmost active fault systems that affect the Central-North Apennines at the Sibillini Mt. Range (Figure 1). The VBFS is located in the hanging wall of the OAS thrust and consists of a ~26 km-long, N150°-striking, SW-dipping normal-fault system with prevailing Quaternary activity, alongside dozens of 1-4 km-long en echelon segments that are accompanied by synthetic and antithetic splays in the main fault's hanging wall (Figure 2). The VBFS's activity strongly controls both the Quaternary deposition and present-day physiography in the Sibillini Mts., which are characterized by two different morphologies in their eastern and western flanks (Figure 2.b). The uplifting footwall block coincides with the eastern flank of the mountain range, while the hanging wall hosts a gentle planation surface westward. The eastern portion consists of several valleys, of which many are narrow canyons that are oriented E-W Tectonics and flow eastward into the Adriatic Sea. The drainage divide is located at the ridge crest of the Sibillini Mts. Close to the range's top, moraines deposits in glacial valleys and cirque morphologies testify the presence of local glaciers above 1750 m at around 28 kyr, contemporaneous to those on the Gran Sasso Massif, with a minor final expansion at 18 kyr [START_REF] Giraudi | I depositi alluvionali olocenici di Campo Imperatore (Massiccio del Gran Sasso-Abruzzo)[END_REF]. The western flank has a smoother morphology characterized by large valleys mainly oriented N-S [START_REF] Coltorti | Quaternary evolution of the Castelluccio di Norcia basin (Umbro-Marchean Apennines, central Italy)[END_REF][START_REF] Pizzi | Quaternary normal faults, intramontane basins and seismicity in the Umbria-Marche-Abruzzi Apennine Ridge (Italy): Tectonics contribution of neotectonic analysis to seismic hazard assessment[END_REF]. Several authors (Blumetti et al., 1993;[START_REF] Calamita | Recent and active extensional tectonics in the southern Umbro-Marchean Apennines (Central Italy)[END_REF][START_REF] Coltorti | A late Lower Pliocene planation surface across the Italian Peninsula: A key tool in neotectonic studies[END_REF][START_REF] Pizzi | Methods for determining the Pleistocene-Holocene component of displacement on active faults reactivating pre-Quaternary structures: Examples from the Central Apennines (Italy)[END_REF] described this smooth topography as a major and unique planation surface from the late lower Pliocene. The VBFS's trace is visible in the morphology and is associated with an abrupt change in the mountain slope that underlined wellpreserved fault scarps throughout the system except in areas where erosional/depositional processes are strong like in the Ussita valley.

This system was mapped and described in detail for the first time by [START_REF] Calamita | Tettonica quaternaria nella dorsale appenninica umbromarchigiana e bacini intrappenninici associati[END_REF].

These authors recognized a main NNW-SSE fault trend that was marked by the presence of several kilometer-long sub-parallel primary and secondary faults (both synthetic and antithetic) with oblique transfer-fault segments, en echelon patterns, and relay zones. In the southernmost sector, two distinct en echelon segments can be recognized at high elevations along Mt. Vettore's western slope, while N160° basal faults with large geologic throws (i.e., >1000 m) border a large endorheic basin: the Piano Grande (Castelluccio Basin), a 12 km-long and 8 km-wide intermountain basin at ~1300 m a.s.l. (Figure 2). The faults high on the flanks of the Mt. Vettore and the one bounding the Piano Grande may sole into a major structure at depth. The development of this basin is also controlled by other differently oriented normal faults around the marginal depression, showing conjugated faults that trend N20° as recognized by tomography (e.g., [START_REF] Villani | A database of the coseismic effects following the 30 October 2016 Norcia earthquake in Central Italy[END_REF]. The SWdipping fault bounding the Piano Grande exhibits a great geological displacement of 1000 m (e.g., [START_REF] Calamita | Tettonica quaternaria nella dorsale appenninica umbromarchigiana e bacini intrappenninici associati[END_REF][START_REF] Pierantoni | Stratigraphic and structural features of the Sibillini mountains (Umbria-Marche Apennines, Italy)[END_REF], but there is no morphological evidence of recent activity with alluvial fans and debris-slope deposits that appears undisturbed since the Middle Pleistocene [START_REF] Coltorti | Quaternary evolution of the Castelluccio di Norcia basin (Umbro-Marchean Apennines, central Italy)[END_REF]. [START_REF] Galadini | Paleoseismology of silent faults in the Central Apennines (Italy): The Mt. Vettore and Laga Mts. faults[END_REF] revealed a recent activity Tectonics (i.e. at least 3 events before the 2016 event) on a secondary fault (i.e., total morphological throw ≤ 3 m and 960 m-long, Figure 2) running 900 m west far from the basin-bounding fault, in the Piano Grande [START_REF] Pierantoni | Stratigraphic and structural features of the Sibillini mountains (Umbria-Marche Apennines, Italy)[END_REF]. The most recent paleoseismological investigations on the antithetic and synthetic splays of the VBFS that ruptured in 2016 suggest that those splays have also experienced earthquakes of Mw ≥ 6.5-6.6, over the last 9 kyr [START_REF] Galli | The Awakening of the Dormant Mount Vettore Fault (2016 Central Italy Earthquake, M w 6.6): Paleoseismic Clues on Its Millennial Silences[END_REF][START_REF] Cinti | 22-kyr-Long Record of Surface Faulting Along the Source of the 30 October 2016 Earthquake (Central Apennines, Italy), From Integrated Paleoseismic Data Sets[END_REF].

The 2016 seismic sequence began on 24 August with a Mw 6.0 earthquake NW of Amatrice [START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF]. The sequence continued on 26 October with a Mw 5.9 event and epicenter close to Visso (Castelsantangelo sul Nera), and then the major Norcia event (Mw 6.5) occurred on 30 October, one of the strongest historical events in Central Italy (Figure 1). The focal-mechanism solutions of these major events are fully consistent with the normal-fault kinematics of the NNWstriking VBFS and, generally, the Central Apennines extension, indicating an ENE-stretching axis.

The first earthquake produced surface faulting for a length of ~5-6 km along the southernmost portion of the VBFS, with an average vertical offset of ~0.10-0.15 m and local peaks over 0.30 m [START_REF] Lavecchia | Ground deformation and source geometry of the 24 August 2016 Amatrice earthquake (Central Italy) investigated through analytical and numerical modeling of DInSAR measurements and structural-geological data[END_REF][START_REF] Pucci | Coseismic ruptures of the 24 August 2016, Mw 6.0 Amatrice earthquake (central Italy)[END_REF]. The 26 October event caused surface faulting in the northernmost portion of the VBFS [START_REF] Pizzi | Fault Segmentation as Constraint to the Occurrence of the Main Shocks of the 2016 Central Italy Seismic Sequence[END_REF][START_REF] Civico | Surface ruptures following the 30 October 2016 M w 6.5 Norcia earthquake, central Italy[END_REF][START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF].

Surface faulting from the last event involved almost the entire length of the VBFS, overprinting the ruptures from the Amatrice earthquake (e.g. [START_REF] Villani | Geometry and structure of a fault -bounded extensional basin by integrating geophysical surveys and seismic anisotropy across the 30 October 2016 Mw 6.5 earthquake fault (central Italy): the Pian Grande di Castelluccio basin[END_REF], and some of the 26 October event [START_REF] Wedmore | Partitioned off-fault deformation in the 2016 Norcia earthquake captured by differential terrestrial laser scanning[END_REF]. All the faults that ruptured during the 2016 seismic sequence, according to [START_REF] Villani | Geometry and structure of a fault -bounded extensional basin by integrating geophysical surveys and seismic anisotropy across the 30 October 2016 Mw 6.5 earthquake fault (central Italy): the Pian Grande di Castelluccio basin[END_REF] database, are reported in Figure 2 as red solid lines.

As observed through detailed geological mapping (e.g., [START_REF] Livio | Surface faulting during the August 24, 2016, Central Italy earthquake (Mw 6.0): preliminary results[END_REF]Pucci et al., 2017 and references therein) and analysis of seismological slip data (e.g., [START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF][START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF][START_REF] Improta | Multi-segment rupture of the 2016 Amatrice-Visso-Norcia seismic sequence (central Italy) constrained by the first high-quality catalog of Early Aftershocks[END_REF], the rupture process and surface-deformation patterns that characterized the 2016 seismic sequence were very complex. The sequence involved the VBFS alongside the Laga Fault (LF in Figure 1) and OAS thrust [START_REF] Lavecchia | Ground deformation and source geometry of the 24 August 2016 Amatrice earthquake (Central Italy) investigated through analytical and numerical modeling of DInSAR measurements and structural-geological data[END_REF][START_REF] Pizzi | Fault Segmentation as Constraint to the Occurrence of the Main Shocks of the 2016 Central Italy Seismic Sequence[END_REF][START_REF] Villani | Geometry and structure of a fault -bounded extensional basin by integrating geophysical surveys and seismic anisotropy across the 30 October 2016 Mw 6.5 earthquake fault (central Italy): the Pian Grande di Castelluccio basin[END_REF][START_REF] Falcucci | The Campotosto seismic gap in between the 2009 and 2016-2017 seismic sequences of central Italy and the role of inherited lithospheric faults in regional seismotectonic settings[END_REF]. The complex surface-deformation patterns that were reconstructed by GPS and DInSAR data inversion (e.g. [START_REF] Cheloni | Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data[END_REF] Tectonics [START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF] revealed interesting information regarding fault linkages and interactions and the role of structural barriers between the VBFS and the Laga Faults. Some authors highlighted how the OAS thrust appears to modulate the evolution of the sequence interfering with coseismic slip distribution and the fault segments interaction [START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF][START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF][START_REF] Ragon | Accounting for uncertain fault geometry in earthquake source inversions -II: application to the Mw 6.2 Amatrice earthquake, central Italy[END_REF]. This interference in the slip propagation is also supported by the rupture interruption for each earthquake in the sequence that determined their respective magnitudes and prevented cascading rupture in a single earthquake of Mw 6.7 or larger [START_REF] Walters | Dual control of fault intersections on stop-start rupture in the 2016 Central Italy seismic sequence[END_REF].

Materials and Methods

To analyze the VBFS in detail, we subdivided the fault system into four main fault sectors that show continuous fault traces and homogeneous structural and geomorphological characteristics.

From south to north, these sectors are the Mt. Vettore, Mt. Porche, Mt. Bove, and Cupi-Ussita synthetic faults and the San Lorenzo antithetic fault, alongside 13 smaller associated fault segments (0.9-2.5 km long) (Figure 2). We define "MV" as the Mt. Vettore-related fault sector, "MP" as the Mt. Porche (and San Lorenzo)-related fault sector, "MB" as the Mt. Bove-related fault sector and "CU" as the Cupi-Ussita-related fault sector.

The MV sector consists of synthetic faults that dip SW and strike between N140° and N175° on the mountain flank that borders the Piano Grande. Although the 30 October earthquake caused surface faulting of a fault in the SW portion of the basin, this antithetic fault has not been analyzed because limited data were available and coseismic ruptures were evident only in a tunnel that remained closed after the earthquakes [START_REF] Galli | L ' eccezionale caso della fagliazione della galleria San Benedetto Il 30 ottobre[END_REF]. The antithetic and synthetic segments of the MP sector define a graben morphology, while two N150° main parallel synthetic segments comprise the MB and CU sectors. We distinguished the latter two into two sectors because no continuity between fault traces was observed across the Ussita valley (Figure 2).

Short-term co-seismic displacement

Tectonics

The short-term displacement of the VBFS has been determined through original field measurements of the coseismic ruptures and integrated with the available database of Villani et al., (2018a).

Because of the high variability of the throws along the fault strike, we identified 84 points and we determined the arithmetic mean of the all throw measurements in the range of 25 meters around each point.

Mid-term cumulative displacements

We refer to mid-term displacements to characterize well-preserved geomorphic evidence of faulting following the Last Glacial Maximum. The Last Glacial Maximum corresponds to a period where changes in the modes of erosion are likely to have controlled the preservation of tectonic offsets (e.g., [START_REF] Peltzer | Offsets of late Quaternary morphology, rate of slip, and recurrence of large earthquakes on the Chang Ma fault (Gansu, China)[END_REF]. Due to the presence of the former neighboring ice sheets (e.g., [START_REF] Giraudi | I depositi alluvionali olocenici di Campo Imperatore (Massiccio del Gran Sasso-Abruzzo)[END_REF], the study area, at elevations between 1300 and 2400 m asl on average, was likely subjected to periglacial conditions during the last glacial phase. In this context, earlier cumulative offsets and fault scarps were potentially erased due to erosional processes (e.g., [START_REF] Peltzer | Offsets of late Quaternary morphology, rate of slip, and recurrence of large earthquakes on the Chang Ma fault (Gansu, China)[END_REF].

This assumption is also supported by 36 Cl exposure dating of bedrock fault scarps in the Apennines that yields ages not older than 12-18 kyr (e.g. [START_REF] Palumbo | Slip history of the Magnola fault (Apennines, Central Italy) from 36Cl surface exposure dating: evidence for strong earthquakes over the Holocene[END_REF][START_REF] Benedetti | Earthquake synchrony and clustering on Fucino faults (Central Italy) as revealed from in situ 36Cl exposure dating[END_REF][START_REF] Cowie | Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults[END_REF]. In particular, the preservation of bedrock fault scarps along active normal faults is related to a strong reduction in rates of rock weathering and erosion, associated with the transition from glacial to interglacial climate [START_REF] Tucker | Geomorphic significance of postglacial bedrock scarps on normal-fault footwalls[END_REF]. Although bedrock fault scarps are more resistant to diffusional processes, they are still subjected to geomorphic processes that shape their surface expression such as channel incisions or landsliding. We thus carefully chose portions of the scarps that did not undergo through erosion or debris flow processes (i.e. no gullies), avoided areas with colluvial sediments or scree deposits [START_REF] Bubeck | The tectonic geomorphology of bedrock scarps on active normal faults Tectonics in the Italian Apennines mapped using combined ground penetrating radar and terrestrial laser scanning[END_REF].

To evaluate mid-term cumulative displacements, we used a high-resolution DEM from Pleiades images that were acquired after the 2016 earthquakes with a resolution of 2 m (courtesy of A. Delorme from IPGP); numerical computations were performed on the S-CAPAD platform, IPGP, France by using MicMac [START_REF] Rosu | Measurement of ground displacement from optical satellite image correlation using the free open-source software MicMac[END_REF]Pleiades image from 2017-01-12). Specifically, we extracted 66 topographic profiles from the DEM along the VBFS. Pleiades images were not available for the area north of the Ussita River (CU sector), so we performed the same analysis by using the available 10-m DEM from [START_REF] Tarquini | Release of a 10-m-resolution DEM for the Italian territory: Comparison with global-coverage DEMs and anaglyph-mode exploration via the web[END_REF], although this approach implied considering a larger confidence interval when evaluating possible measurement errors.

The profiles were densely spaced (every ∼200 m) in areas where the fault scarp is well preserved, while we traced fewer profiles in areas where the cumulative offset is not adequately detectable, and only where measurements were possible (e.g.; Mt. Bicco fault profile, average spacing ∼300 m).

These profiles exhibited fault scarps with common characteristic features such as a displaced reference surface, a degraded scarp, a free face, and a colluvial wedge (Figure 3.a). The reference surface constituted a marker topographic horizon that could be distinguished in both the footwall (upper surface) and the hanging-wall (lower surface) of the fault and that was displaced following repeated faulting events affecting a regular topography that was previously leveled by a glacial phase. The free face is the approximation of the fault plane that began to be eroded after exhumation (by earthquakes), accumulating in the colluvial wedge at the base above the lower surface.

In general, fault-related scarps are generally strongly affected by degradation and aggradation processes (diffusion) that modify their original shape [START_REF] Tectonics Civico | Morphotectonic analysis of the long-term surface expression of the 2009 L'Aquila earthquake fault (Central Italy) using airborne LiDAR data[END_REF], especially in slowly deforming tectonic environments such as Italy, Greece or Spain [START_REF] Caputo | The Greek Database of Seismogenic Sources (GreDaSS): state-of-the-art for northern Greece[END_REF][START_REF] Galli | Twenty years of paleoseismology in Italy[END_REF][START_REF] Perez | A pragmatic approach to seismic parameters in a region with low seismicity: the case of eastern Iberia[END_REF]. As the footwall of a normal fault undergoes continuous uplift by repeated earthquakes, the upper surface goes through erosional processes, which modify the original slope angle. To distinguish these characteristic features, all the profiles were drawn with a length of 300 m to better identify the displaced upper and lower surfaces, reducing the uncertainty from erosional processes. Because of the low steepness (∼3°) in correspondence with the Piano Grande, we traced four profiles with a length of 1000 m to ensure the morphological detection of the fault (MV5).

We measured the vertical displacement that was recorded by the upper and lower reference surfaces for each profile. For each topographic profile, we manually identified two reference surfaces (red line in figure S4) in the upper and the lower part having the same slope.

In some cases, the footwall slope is steeper than the one on the hanging wall and the identification of the reference surface is not easy. In that case, thanks to the high density of the performed topographic profiles (every ∼200 m) we use as reference surface the one of a well-constrained proximal profile. In addition, when it was possible (e.g. Profiles MV 4.3, MV 4.5, MV 4.7), we defined more than one reference surface and we determined an average value of sloping surface with the associated error (see supplementary). The manual analysis was associated, for some profiles, to the semi-automated algorithm SPARTA (Scarp PARameteTer Algorithm) analysis, developed by [START_REF] Hodge | A semiautomated algorithm to quantify scarp morphology (SPARTA): application to normal faults in southern Malawi[END_REF]. Specifically, this algorithm calculates the parameters of the fault scarp (i.e. height, width, and slope) from a scarp topographic profile by performing a best-fit calculation to a scarp-like template. Moreover, it enhances the clarity of the elevation profiles by filtering a range of non-tectonic features, such as vegetation peaks in DEMs from Pleiades images, through four digital filters (see details in Hodge et al. 2019 and references therein).

The vertical offsets determined by SPARTA and by manual measurements were very similar (see the supplementary material for details). Among the analyzed 66 profiles, 40 were qualified as poorly constrained and could not be analyzed by SPARTA. This is related to the badly preserved topographic fault scarp, such as in the Mt. Porche sector, or the poorly constrained upper and lower surfaces for example in the Mt. Vettore and Mt. Bove sectors mainly because of the presence of a great amount of scree deposits in the hanging-wall block. Those profiles were thus associated with a higher uncertainty (see the supplementary).

Where a topographic slope dips in the same direction as the fault dip, the topographic offset is less than the true vertical displacement; wherever the two dips have opposite directions, the topographic offset is larger than the real throw [START_REF] Bull | Tectonic geomorphology of mountains: a new approach to paleoseismology[END_REF]. Thus, we corrected the topographic offsets (To) to obtain true vertical displacements (Tr) by using the equation of [START_REF] Bull | Tectonic geomorphology of mountains: a new approach to paleoseismology[END_REF], who considered the dip angle of the fault (α) and steepness (β) of the displaced topographic surface (Figure 3.a):

Tr = (To [sinα * sin(90°+ β)])/sin(α -β) (1)
The dip angles of the faults (α) are from field measurements and the database of Villani et al. (2018a). The dip angles vary between 56° and 90° with the most frequent values being between 70° and 73° 19%), and between 76°and 77° (17%) (Fig. S2 in supplementary) and a mean value of 73 ±6.7°. Where the bedrock fault plane is not outcropping (e.g. MP-sector) and the fault dip angle is unknown we use this mean dip angle value. Considering the most frequent values of the dip angles are 70°-77°, the uncertainty on the down-throw is ± 5 %. Whereas, considering the two endmember values of 56° and 90°, the related uncertainty would be ± 8%.

Long term Geological displacements

We constructed seven geological cross-sections (traces in Figure 2.a) to determine the long-term geological down-throw of the VBFS with particular focus on the faults that were active in 2016.

Starting from the available geological maps by [START_REF] Calamita | Tettonica quaternaria nella dorsale appenninica umbromarchigiana e bacini intrappenninici associati[END_REF] and [START_REF] Pierantoni | Stratigraphic and structural features of the Sibillini mountains (Umbria-Marche Apennines, Italy)[END_REF], original field mapping was conducted to integrate and update the geological structural map of the area (Figure 2.a). Field surveys were conducted in some key areas (e.g., Mt. Bicco, Mt. Porche and Mt. Lieto in Figure 2) to better constrain the fault throw.

Given the complexity of the structural evolution of the study area (see section 2), we used the Marne a Fucoidi Fm. (Lower Cretaceous) as a reference marker to determine the vertical offset along the cross-sections. We made this choice because this formation is present throughout the region, has a constant thickness between 50 and 80 m, and records the total extension across the structures as a pre-Quaternary horizon. However, distinguishing pre-Quaternary displacements from the total down-throw is sometimes difficult, and the Quaternary fault displacements and slip rate can be overestimated (see section 2). Therefore, we analyzed only normal faults that showed morphological evidence of activity (i.e., after 18 kyr). Finally, we estimated the accuracy for around

Results

This section is divided into three sub-sections: (1) a presentation of long-and mid-term throw data plotted along a transect line that approximates the average strike of N150° for the VBFS (see the location in Figure 2), (2) a comparison with the 2016 coseismic throws plotted over the same transect line, and (3) an interpretation of the three databases and the determination of the throw rates.

Geological throw (long-term)

The throw values that are obtained from geological cross-sections define the long-term history of the VBFS and are useful for understanding the relative age of the fault segments, helping us define a constant long-term throw rate for Quaternary active normal faults.

Morphological throws (mid-term)

The morphological throw that was related to the post-LGM activity of the VBFS was evaluated through fault-scarp recognition and measurements on high-resolution topographic profiles following the method in section 3.

Measured throws depend on the slip vectors (net slip) and their direction. When fault planes are exposed at the base of a fault scarp, striae provide measurements of the net-slip vector (see Figure 3.b). Depending on the variability of the strike of the fault, i.e., some faults that deviate from pure ENE extension, the slip vector may show a slight strike-slip component [START_REF] Perouse | Coseismic slip vectors of 24 August and 30 October 2016 earthquakes in Central Italy: Oblique slip and regional kinematic implications[END_REF]. The throw corresponds to the vertical component of the slip, which we assume represents the dip-slip component (Figure 3.b). In the hypothesis of an oblique vector, the net slip is distributed on the vertical (dip slip) and horizontal components (strike slip). Therefore, before analyzing the throw variation, we first question how much the strike-slip component, which is mostly present where the fault plane produces strike-bending, can influence the measured topographic offset along the VBFS.

Figure 5 shows the bedrock fault-plane measurements (the site's location is indicated in the supplementary materials) with strong strike-slip (left-or right-lateral) components; each measurement has three components, all shown in meters to facilitate comparison with the measured topographic offset (i.e., the down-throw), namely, the net slip (total slip vector), dip slip, and strike slip.

The field structural data showed that the strike of the bedrock fault planes ranged between N120° and N190°, with kinematic indicators showing rake values between 70° and 96°. We determined the net-slip vector of each site by considering the slip-vector geometry from these data and the downthrow from the measured topographic offset. When considering a 70° rake angle, the net slip comprised at most 34% of strike slip component. This only occurs in the MV sector, where there is a quite strong strike slip component [START_REF] Perouse | Coseismic slip vectors of 24 August and 30 October 2016 earthquakes in Central Italy: Oblique slip and regional kinematic implications[END_REF] but still it is not affecting the results since it is within the uncertainties that we get for the down throw in this area. As shown in Figure 5, the lateral component is lower than 20% and still within the uncertainties of the down throw. Thus, we can assume that the topographic offset is within uncertainty similar to the net slip in most areas along the VBFS.

To show the contribution from each fault segment to the VBFS's mid-term growth, we plotted the throw value for each post-glacial fault scarp along the transect line in The total cumulative mid-term throws (i.e. the summed throws at each point) along the transect line showed a slip distribution that matched the throws of each segment for the same sector. In particular, the maximum/minimum total cumulative throws correspond to the location of the maximum/minimum throws at the same position along strike; this pattern suggests sites of preferred surface slip along the VBFS.

Comparison with the 2016 coseismic throw (short-term)

The short-term throw, which was measured in the field after the 2016 seismic events, varied along the VBFS. The coseismic ruptures showed maximum throws in the southern portion of the fault system, reaching almost 2 m and lower values north of the MV sector, where the throws did not exceed 1 m (Villani et al. 2018a).

The comparison of the profile shapes from the analysis of the three different time scales for the active faults denoted an agreement between the mid-and short-term throw profiles. The maxima of the two throw profiles are located in the same positions along the strike. The coseismic throw profiles and mid-term cumulative-throw profiles from the addition of several earthquakes developed asymmetric patterns, with the highest throw in the southern area (MV sector, between 4 and 6 km on the transect line). The profiles both showed a decrease in the throw, which reached zero within 2 km, at the southern tip of the VBFS.

In addition to the good match between post-LGM (mid-term) and short-term throws in the southern sector, the coseismic rupture pattern throughout the fault system sometimes deviated from what was recorded on the morphology. For instance, the coseismic ruptures in the MP sector (9 km along the transect line, Figure 4.c) reached a value of 95 cm above the mountain crest. However, we did not observe any morphological evidence of a fault scarp in this area. Between 16 and 18 km, two different throws were found in the Mt. Bove sector for the mid-and long-term scales (i.e., geological throw = 800 m and post-LGM throw = 30 m), which were not observed in the short-term profile (i.e., 50 cm of coseismic rupture).

Common elements at all time scales for the active faults at the surface were observed between 18 and 20 km on the transect line in the Ussita valley. No evidence of geological fault traces characterized the area [START_REF] Pierantoni | Stratigraphic and structural features of the Sibillini mountains (Umbria-Marche Apennines, Italy)[END_REF][START_REF] Pizzi | Fault Segmentation as Constraint to the Occurrence of the Main Shocks of the 2016 Central Italy Seismic Sequence[END_REF][START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF][START_REF] Porreca | 3D geological reconstruction of the M. Vettore seismogenic fault system (Central Apennines, Italy): Cross-cutting relationship with the M. Sibillini thrust[END_REF], suggesting that this region was not affected by faulting over the last 18 kyr. This lack of faulted areas matches the evidence that the Ussita River is the only westward-flowing river that bypasses the drainage divide of the Central Apennines range. In addition, no clear coseismic ruptures occurred in this area during the 2016 seismic sequence. The occurrence of the coseismic ruptures north of this valley (at the Cupi-Ussita segments) suggests that the northernmost tip of the system is on the other side of the Ussita valley. Thus, rather than an area not interested by the faults, we observed a zone of minimum surface slip, persistent in time.

According to a quantitative analysis of the matching shape profiles, the mid-and short-term throw distributions in the Mt. Vettore sector showed a very good relationship. In particular, the cumulative profiles at mid-and short-term are very similar: both have the maximum throw between 4 and 6 km along the transect line and decrease rapidly within 2 km (Figure 4.b and c). The highest and lowest values are constantly recorded on the fault segments MV2 and MV5, respectively. Moreover, the ratio between the short-and mid-term throw values is shown for each segment in the MV sector and at each measured point, having a good correlation factor (r = 0.7, Figure 6).

Throw rates and fault-system evolution

Based on the above data, we could reconstruct the VBFS's evolution from its onset in the Early Quaternary to the present. The evolution through time of VBFS has been determined from the vertical slip rates. We traced cross-sections that were orthogonal to the reference transect line, along which we summed the maximum cumulative displacement of all the fault segments belonging to each fault sector (MV, MP, MB, and CU). To avoid overestimation, we choose the cumulative displacement from the best-constrained topographic profile, having low errors in the offset measurements. In addition, we calculated the slip rate along the fault considering that the cumulative offset is bracketed between the total cumulative offset and the total cumulative offset minus the measured 2016 coseismic offset, assuming a periodic behavior. We implied the highest throws for each sector, so the obtained values are to be considered the maximum throw rates for each sector. Significant variations in the throw distribution and throw rates appeared in both time and space.

For the mid-term maximum throw rate, thus the rate calculated over 18 kyr, we found a heterogeneous pattern of the VBFS. The MV sector's throw rate is 1.65 ± 0.05 mm/yr (total cumulative offset 31.8 m and coseismic offset of 2.8 m). The throw rates for the MP sector is 0.95 ± 0.5 mm/yr (total cumulative offset 18 m and coseismic offset of 0.9m), for the MB sector 1.25 ± 0.5 mm/yr (total cumulative offset 24 m and coseismic offset of 0.7 m); and for the CU sector the velocity is 0.5 mm/yr (total cumulative offset 9.1 m and coseismic offset of 0.1 m). The throw rate determined on the fault with the highest throw (MV2) is 1.3 ± 0.1 mm/yr and it matches the value of 1.31± 0.27 mm/yr determined by [START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF] over the last 15 kyr.

The long-term slip history of the VBFS is affected by uncertainties that are related to the absence of accurate chronology on the onset of the segments and the duration of activity along these faults without evidence of activity after the LGM. To determine the long-term throw rates, we considered only active faults (all faults with morphological evidence) and calculated their velocities since the beginning of extension (1.1-1.2 Ma, [START_REF] Blumetti | Il Pleistocene inferiore nell'area nursina[END_REF]Coltorti et al., 1998;Calamita et al., 1999). The Mt. Bove and Mt. Porche sectors hosted the active segments with the highest throws (800 m of cumulated displacement and 500 m as the highest throw for single fault segment), suggesting major activity along these faults over long time scales. We found a maximum throw rate of 0.8 mm/yr when considering the highest vertical geological displacements of the entire VBFS.

Tectonics

The obtained value was within the range of slip rates that were estimated by [START_REF] Pizzi | Quaternary normal faults, intramontane basins and seismicity in the Umbria-Marche-Abruzzi Apennine Ridge (Italy): Tectonics contribution of neotectonic analysis to seismic hazard assessment[END_REF] for the VBFS (0.6-0.9 mm/yr). The throw rates of the Central Apennines' fault systems range between <0.2 and 1-2 mm/yr [START_REF] Barchi | Sintesi delle conoscenze sulle faglie attive in Italia Centrale: parametrizzazione ai fini della caratterizzazione della pericolosità sismica[END_REF][START_REF] Benedetti | Earthquake synchrony and clustering on Fucino faults (Central Italy) as revealed from in situ 36Cl exposure dating[END_REF][START_REF] Roberts | Spatial and temporal variations in growth rates along active normal fault systems: An example from The Lazio-Abruzzo Apennines, central Italy[END_REF][START_REF] Papanikolaou | Fault scarps and deformation rates in Lazio-Abruzzo, Central Italy: Comparison between geological fault slip-rate and GPS data[END_REF]Civico et al., 2015b;[START_REF] Cowie | Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults[END_REF]. The high values of the VBFS are reached by the Fucino fault: from 0.55 (at the tips) to 2 mm/yr (in the center of the system). The variation in the throw rate along the Fucino fault system was interpreted to be an increase in the growth rate over the last 700 kyr [START_REF] Cowie | Constraining slip rates and spacings for active normal faults[END_REF][START_REF] Roberts | Spatial and temporal variations in growth rates along active normal fault systems: An example from The Lazio-Abruzzo Apennines, central Italy[END_REF].

Throw rates for the VBFS are higher than some faults in the Northern Apennines, such as the Colfiorito fault that is suggested to have a rate of 0.3 mm/yr by [START_REF] Barchi | Sintesi delle conoscenze sulle faglie attive in Italia Centrale: parametrizzazione ai fini della caratterizzazione della pericolosità sismica[END_REF], and Mirabella (2016) and 0.67 ± 0.13 mm/yr by [START_REF] Mildon | Active normal faulting during the 1997 seismic sequence in Colfiorito, Umbria: Did slip propagate to the surface?[END_REF].

From our results, it appears that the segments with high geological displacement but without post-

LGM activity are mainly located at a low elevation close to the Quaternary basin's boundaries (e.g., MV8 fault bounds the Piano Grande). Whereas fault associated with the highest mid-and shortterm throws are generally located at a higher elevation close to the ridges (e.g., MV2 fault at Mt.

Vettore), or even on the ridge close to the drainage divide (e.g., MP2 fault at Mt. Porche). This observation suggests that the most recently activated segments are located on the footwall of the faults that were formerly active probably during an earlier stage of the extension, suggesting there might be a shift of the activity at least for about 18 kyr.

Moreover, the maximum activity (in terms of throws pattern) at mid-and short-term scales were concentrated in the southern sector of Mt. Vettore with high throw rates. The good linear correlation between the short-and mid-term scales (Figure 6) might suggest that the fault system evolved with a similar pattern over time since at least the last 18 kyr. Figure 7 shows the evolution of the throw both in time and space of the VBFS. The maximum throw is localized on the MV-sector since the last 18-kyr associated with a higher rate of slip increment compared to the other sectors of MP, MB, and CU.

Tectonics

Thus, assuming a constant maximum throw rate of 1.65 ± 0.5 mm/yr, calculated from the mid-term, and considering 380 m of cumulative geological displacements, evaluated by the sum of the max displacement of each segment in the cross-sections, we could infer an origin of the active faults at the surface at Mt. Vettore at about ~ 200-250 kyr ago. Considering the general onset of the VBFS was 1.1-1.2 Myr [START_REF] Blumetti | Il Pleistocene inferiore nell'area nursina[END_REF]Coltorti et al., 1998;Calamita et al., 1999; see section 2), and the uncertainties about the age and throw of the basin boundary fault (see section 2), the MV sector would be characterized by younger faults. The resolution of the available sub-surface data [START_REF] Porreca | Seismic reflection profiles and subsurface geology of the area interested by the 2016-2017 earthquake sequence (Central Italy)[END_REF] does not allowed determining how the active faults and the basin boundary fault are related at depth. But from our surface data the presence of these young faults might be interpreted or as a consequence of the southward propagation of the fault system (i.e.

from the MB-MP-sectors to the MV-sector) or due to an activity "replacement" of the older basin boundary fault at the surface, probably at ~200-250 kyr.

This southern tip of the system hosts high-density, widespread, short unlinked and newly formed faults, marking a relatively more distributed deformed volume than a single master fault that accommodated seismic slip in a narrower zone, such as in the northern VBFS (Figure 7).

Discussion

The detailed mapping of the 2016 coseismic ruptures clearly showed that a well-defined peak at its southern tip in the MV sector characterized the throw-distribution pattern along the VBFS. In particular, in agreement with many authors [START_REF] Lavecchia | Ground deformation and source geometry of the 24 August 2016 Amatrice earthquake (Central Italy) investigated through analytical and numerical modeling of DInSAR measurements and structural-geological data[END_REF][START_REF] Livio | Surface faulting during the August 24, 2016, Central Italy earthquake (Mw 6.0): preliminary results[END_REF][START_REF] Pucci | Coseismic ruptures of the 24 August 2016, Mw 6.0 Amatrice earthquake (central Italy)[END_REF][START_REF] Civico | Surface ruptures following the 30 October 2016 M w 6.5 Norcia earthquake, central Italy[END_REF][START_REF] Villani | Geometry and structure of a fault -bounded extensional basin by integrating geophysical surveys and seismic anisotropy across the 30 October 2016 Mw 6.5 earthquake fault (central Italy): the Pian Grande di Castelluccio basin[END_REF], the coseismic throws at Mt. Vettore were ~ 0.10-0.15 m (with a local maximum of 0.30 m), and ~1.5 m (locally reaching 2 m) for the 24 August event (Mw 6.0), and the 30 October event (Mw 6.5), respectively. These high values went beyond the expected values from the empirical relationships between the magnitude vs surface displacement [START_REF] Wells | New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement[END_REF]. In particular, the recorded slip at Mt. Vettore after the Tectonics 30 October event exceeded the power-law and exponential scaling by two orders of magnitude [START_REF] Villani | Geometry and structure of a fault -bounded extensional basin by integrating geophysical surveys and seismic anisotropy across the 30 October 2016 Mw 6.5 earthquake fault (central Italy): the Pian Grande di Castelluccio basin[END_REF].

According to the slip models obtained from strong motions, GPS, and DInSAR for 24 August and 30 October 2016 events (e.g. [START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF][START_REF] Cheloni | Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data[END_REF][START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF]Walter et al., 2018;[START_REF] Ragon | Accounting for uncertain fault geometry in earthquake source inversions -II: application to the Mw 6.2 Amatrice earthquake, central Italy[END_REF], the rupture propagated to the surface mainly in the MV sector. In this sector, the rupture propagated to the surface producing in 6-8 seconds the highest observed coseismic slip of the entire system [START_REF] Wilkinson | Near-field fault slip of the 2016 Vettore M w 6.6 earthquake (Central Italy) measured using low-cost GNSS[END_REF], along with significant off-fault deformation that occurred close to those faults with spectacular surface offsets (Delorme et al., 2020).

Furthermore, some authors (e.g. [START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF][START_REF] Walters | Dual control of fault intersections on stop-start rupture in the 2016 Central Italy seismic sequence[END_REF] suggested that the ruptures did propagate at depth, in the first ~5-6 km, at the fault intersections between the VFBS and the LF, where also slip occurred.

The earthquakes on both 24 August and 30 October with epicenters located to the south and north of the trace of the OAS thrust ramp, respectively, produced the maximum surface displacement along the same fault segments in the MV sector (e.g., [START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF][START_REF] Gori | Surface faulting caused by the 2016 central Italy seismic sequence: Field mapping and LiDAR/UAV imaging[END_REF]. The throw distribution pattern of the 2016 coseismic rupture has been defined by many authors (e.g., [START_REF] Villani | Geometry and structure of a fault -bounded extensional basin by integrating geophysical surveys and seismic anisotropy across the 30 October 2016 Mw 6.5 earthquake fault (central Italy): the Pian Grande di Castelluccio basin[END_REF][START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF] as an anomaly in the slip concentration at the MV sector (both 24 August and 30 October).

Slip profiles and fault throw at various time scales

One of the main results from our study noted that the anomalous slip concentration in the MV sector is not a phenomenon that only refers to the 2016 seismic sequence, but rather constitutes the characteristic method through which the Mt. Vettore fault has broken during at least the last 18 kyr.

The similarity between the along strike displacement recorded in the short-term and mid-term profiles in the MV-sector can be interpreted either as the faults have experienced a similar rupturing pattern over the last 18 kyr; or as individual successive earthquakes with variable slip distributions Tectonics produce an overall cumulative pattern over the last 18 kyr similar, to the one observed for the 2016 short-term one.

Paleoseismological trench studies [START_REF] Galadini | Paleoseismology of silent faults in the Central Apennines (Italy): The Mt. Vettore and Laga Mts. faults[END_REF][START_REF] Galli | The Awakening of the Dormant Mount Vettore Fault (2016 Central Italy Earthquake, M w 6.6): Paleoseismic Clues on Its Millennial Silences[END_REF][START_REF] Cinti | 22-kyr-Long Record of Surface Faulting Along the Source of the 30 October 2016 Earthquake (Central Apennines, Italy), From Integrated Paleoseismic Data Sets[END_REF], suggest that not only the MV sector but the entire system experienced at least seven events of Mw ≈ 6.5, thus similar to the 2016 Norcia-type (or larger) surface-faulting event, over the last 22 kyr.

Comparing the vertical displacements of the penultimate event found in the trenches (E2 occurred ~4th -5 th century CE) for segments MV, MP4, and MP5, we found a pattern that seems to agree quite well with the constant growth pattern of the mid-and short-time scale (Figure 8). Those results also infer that the rupturing pattern is similar to the one observed in 2016, with multiple fault segments rupturing during a single individual event. This evidence strengthens the first hypothesis of the repeating self-similar rupturing pattern, where different seismic events produce the analogous slip distribution, with maxima throws always on the same fault segments. Thus, the asymmetric, triangular throw profiles of the VBFS that were created in tens of seconds (2016 coseismic ruptures) and over tens of thousands of years (cumulative fault scarp) resemble each other (see Figs. 4 and9). This similarity has also been observed by [START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF], [START_REF] Iezzi | Coseismic throw variation across along-strike bends on active normal faults: Tectonics Implications for displacement versus length scaling of earthquake ruptures[END_REF] in some faults of the Mt.Vettore (specifically, MV1, MV2, MV3, MV4 and MV5 in our study), whether at morphological, geological scale or in terms of the largest topographic relief. A different interpretation, however, has been hypothesized for this evidence. In particular, [START_REF] Iezzi | Coseismic throw variation across along-strike bends on active normal faults: Tectonics Implications for displacement versus length scaling of earthquake ruptures[END_REF] interpreted this highest slip concentration in the Mt. Vettore faults as a consequence of the particular local structural fault geometry suggesting that throw increased because of a slip vector accommodation due to a bending of the fault strike of ~28° and to the related fault dip angle increase. Brozzetti et al. (2018) suggested that this anomaly might be due to irregularities of the fault at depth due to local tectonic factors, such as the suggested back tilting that amplified the coseismic displacement in this area [START_REF] Testa | Mapping the geology of the 2016 Central Italy earthquake fault (Mt. Vettore -Mt. Bove fault, Sibillini Mts.): geological details on the Cupi -Ussita and Mt. Bove -Mt. Porche segments and overall pattern of coseismic surface faulting[END_REF].

Tectonics

Our results also suggest that the segment MV2 in the Mt.Vettore is not the only one to exhibit such high throw since all the other segments in this sector displayed relatively high throw compared to the other segments of the VBFS. If we consider the ratio between the height of the post-LGM fault scarp and the value of the 2016 coseismic ruptures along the main fault at Mt. Vettore and its subparallel segments, we obtain a constant value. Thus, we interpret the MV sector of the VBFS as having homothetic growth behavior, with an anomalous high displacement on all the segments, suggesting that those are interacting [START_REF] Gupta | A model of normal fault interaction based on observations and theory[END_REF][START_REF] Mirabella | Segmentation and interaction of normal faults within the Colfiorito fault system (central Italy)[END_REF].

As observed by [START_REF] Duross | Fault segmentation: New concepts from the Wasatch fault zone, Utah, USA[END_REF] in the Wasatch Fault Zone (Basin and Range Province) from paleoseismological studies, the possibility of interaction between segments in areas of structural complexity seems to permit more complex fault ruptures, such as the multi or partial rupturing of segments observed in the 2016 seismic sequence [START_REF] Villani | Geometry and structure of a fault -bounded extensional basin by integrating geophysical surveys and seismic anisotropy across the 30 October 2016 Mw 6.5 earthquake fault (central Italy): the Pian Grande di Castelluccio basin[END_REF]. In addition, as we observed for the MV sector in the VBFS, the Wasatch Fault Zone corresponds to the fault tip of a wider fault system. Studies on vertical displacements performed on this latter showed how the Wasatch Fault Zone is characterized by the highest fault throws, ∼20 m of throw versus ∼10 m in the other "zones" (Friedrich et al., 2003 and reference therein). This exceeding throw at the Wasatch Fault Zone has been interpreted as an acceleration in the throw rates during the Holocene [START_REF] Friedrich | Comparison of geodetic and geologic data from the Wasatch region, Utah, and implications for the spectral character of Earth deformation at periods of 10 to 10 million years[END_REF]2003).

Furthermore, according to the classification of fault structural maturity described by [START_REF] Dolan | How well do surface slip measurements track slip at depth in large strike-slip earthquakes? The importance of fault structural maturity in controlling on-fault slip versus off-fault surface deformation[END_REF] and [START_REF] Nicol | Normal fault interactions, paleoearthquakes and growth in an active rift[END_REF], the frequent fault-strike variation associated with the VBFS's southern sector would suggest that it is structurally immature compared to the northern area (MP-MB-CU sectors), where the deformation is concentrated on the main fault structures. Moreover, the overall low velocities of slip propagation at depth were 3.1 km/s for the Mw 6.0 event, 2.7 km/s for the Mw 5.9 event and 2.7 km/s for the Mw 6.5 event, as obtained by finite-fault analysis [START_REF] Tinti | Slip heterogeneity and directivity of the ML 6.0, 2016, Amatrice earthquake estimated with rapid finite-fault inversion[END_REF][START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF]. These values, as well the fault parameters that define the structural maturity in [START_REF] Perrin | Location of largest earthquake slip and fast rupture controlled by along-strike change in fault structural maturity due to fault growth[END_REF] and references therein, indicate that the entire system VFBS system is actually classified as immature (e.g. rupture velocities of <3 km/s, fault length < 300 km, initiation age < few Ma).

Role of inherited structures

In an evolving extensional active system such as the VBFS, what can cause such preferred slip zones towards a tip of the fault system, thus an activity concentration and a slip gradient increasing?

Two possibilities have been previously suggested for such observation: (1) a fault-linkage zone, where the slip is concentrated at the tips of two overlapping faults (e.g., [START_REF] Peacock | Displacement, segment linakge and relay ramps in normal fault zones[END_REF], and (2) a fault-barrier zone, where the fault slip increases as a response to the inhibition of lateral fault propagation because of interference with a major "barrier" at depth (e.g., [START_REF] Madariaga | On the relation between seismic moment and stress drop in the presence of stress and strength heterogeneity[END_REF][START_REF] Lay | An asperity model of large earthquake sequences[END_REF][START_REF] Das | Breaking of a single asperity: Rupture process and seismic radiation[END_REF][START_REF] Mendoza | Coseismic slip of two large Mexican earthquakes from teleseismic body waveforms: Implications for asperity interaction in the Michoacan Plate Boundary Segment[END_REF][START_REF] Ruff | Rupture process of large earthquakes in the northern Mexico subduction zone[END_REF][START_REF] Somerville | Characterizing crustal earthquake slip models for the prediction of strong ground motion[END_REF][START_REF] Das | Spontaneous complex earthquake rupture propagation[END_REF][START_REF] Manighetti | Slip accumulation and lateral propagation of active normal faults in Afar[END_REF]2005).

In the hypothesis of a "fault-linkage zone", the asymmetric maximum displacement in the VBFS would be the result of the natural evolution of the fault system that starts to interact with another fault system, in agreement with the evolutional model of a fault system as observed in Gawthorpe and Leeder (2000). The southern tip of the VBFS would be propagating toward the Laga Fault (LF), which in turn has an asymmetric geological displacement profile with a maximum in its northern part [START_REF] Boncio | Seismogenesis in Central Apennines, Italy: an integrated analysis of minor earthquake sequences and structural data in the Amatrice-Campotosto area[END_REF], through a zone with no evidence of faulting at the surface. The interaction at depth between the VBFS and the LF, however, seems supported by the occurrence of the location of the Mw 6.0 event on 24 August [START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF] in the relay zone of the two systems, away ⁓9 km and ⁓7 km from the VBFS and LF, respectively (see Figures 1 and9).

The second broad class of studies suggest the presence of a "fault-barrier zone". Although the concept of a "barrier" is still debated by many authors, this terminology can describe a zone that prevents slip propagation and allows high-throw gradients to be maintained [START_REF] Manighetti | Evidence for selfsimilar, triangular slip distributions on earthquakes: Implications for earthquake and fault mechanics[END_REF]. Whatever the process, these areas are affected by specific mechanical or rheological properties and a resistance to the coseismic rupture. In the context of the VBFS, the geometrical relationship with a potential barrier at depth is still debated and difficult to reconstruct due to the lack of robust subsurface data.

But the occurrence of the 2016 seismic event provided new insights in understanding the interaction (both at the surface and depth), of the VBFS with the crustal pre-existing oblique OAS thrust ramp, which previous authors assumed as a structural barrier [START_REF] Pizzi | Pre-existing cross-structures and active fault segmentation in the northern-central Apennines (Italy)[END_REF]. At the surface (Figure 9), the coseismic ruptures of the VBFS crosscut the trace of the OAS thrust (e.g., [START_REF] Bonini | Imaging the tectonic framework of the 24 August 2016, Amatrice (central Italy) earthquake sequence: new roles for old players?[END_REF][START_REF] Livio | Surface faulting during the August 24, 2016, Central Italy earthquake (Mw 6.0): preliminary results[END_REF][START_REF] Pucci | Coseismic ruptures of the 24 August 2016, Mw 6.0 Amatrice earthquake (central Italy)[END_REF][START_REF] Pizzi | Fault Segmentation as Constraint to the Occurrence of the Main Shocks of the 2016 Central Italy Seismic Sequence[END_REF][START_REF] Iezzi | Coseismic throw variation across along-strike bends on active normal faults: Tectonics Implications for displacement versus length scaling of earthquake ruptures[END_REF]Villani et al., 2018a,b;[START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF][START_REF] Porreca | 3D geological reconstruction of the M. Vettore seismogenic fault system (Central Apennines, Italy): Cross-cutting relationship with the M. Sibillini thrust[END_REF]. While at depth, slip models from different datasets showed how the mainshocks-rupturing process interacted with the deep high-angle part of the OAS thrust [START_REF] Tinti | Slip heterogeneity and directivity of the ML 6.0, 2016, Amatrice earthquake estimated with rapid finite-fault inversion[END_REF][START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF][START_REF] Cheloni | Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data[END_REF][START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF][START_REF] Ragon | Accounting for uncertain fault geometry in earthquake source inversions -II: application to the Mw 6.2 Amatrice earthquake, central Italy[END_REF]Gallovič et al., 2019).

Furthermore, the slip model of [START_REF] Ragon | Accounting for uncertain fault geometry in earthquake source inversions -II: application to the Mw 6.2 Amatrice earthquake, central Italy[END_REF], which was derived from GPS analysis, suggested that the rupture on 24 August had a bi-lateral propagation direction. The slip, which was plotted on a 45°-dipping fault plane, was confined to the south in a narrow zone 2-5 km deep [START_REF] Walters | Dual control of fault intersections on stop-start rupture in the 2016 Central Italy seismic sequence[END_REF], and to the north was more distributed , propagating both downdip (until 8-9

km depth) and climbing up towards the surface (above 3 km depth in the MV sector). In agreement with Ragon et al. (2019, and references therein), we suggest that the modalities of the northward slip transfer could have been controlled by the presence of the high-angle OAS thrust ramp, which prevented the lateral northward propagation of the rupture. On the other hand, the hypocenter of the 24 August event was located on the footwall of the OAS thrust, while the rupture reached the surface only on its hanging-wall. This observation suggests that the rupture bypassed the OAS Vettore-Mt. Porche. The hypocenter was at 9.5 km depth, where the rupture nucleated and mainly expanded towards the surface. In correspondence with the OAS thrust at depth, this rupturing only crossed it between 5 and 7 km depth, triggering a small patch of around 50-100 cm of slip south of the OAS thrust. All the patches with slip above 100 cm were located north of the OAS thrust, defining a rupture area whose southward limit seemed to follow the OAS thrust. On the other hand, [START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF] and [START_REF] Improta | Multi-segment rupture of the 2016 Amatrice-Visso-Norcia seismic sequence (central Italy) constrained by the first high-quality catalog of Early Aftershocks[END_REF] modeled the rupture distribution with the OAS thrust as a source in their kinematic inversion. Although we agree that some slip could have occurred on the OAS thrust ramp, we believe the VBFS was the major source of this event according to our results and the focal mechanism, which corresponds to an NNW-SSE dip-slip fault.

Therefore, these two slip models for the 24 August and the 30 October suggest a major slip interference at depth (below ~ 5 km), that may be interpreted as a barrier producing an interruption in the lateral slip propagation (northward and southward, respectively), in favor of a transferring rupture toward the surface, at the MV sector.

In this hypothesis, the presence of a deep barrier is observed at the surface from a major fault slip accumulation and other features such as fault interactions, and fault fragmentation associated with bends [START_REF] Manighetti | Evidence for selfsimilar, triangular slip distributions on earthquakes: Implications for earthquake and fault mechanics[END_REF].

Based on our long-mid-and short-term surface data and the 2016 rupturing scenario from the aftermentioned inversion slip models, we interpret the maximum throw in the southern tip at the MV sector, as the result of southward increase in the rate of fault system activity (occurred between 1.2 Ma and 18 kyr, see Figure 7). The suggested southward growth in fault activity (see section 4.4) could indicate an ongoing linkage process with the Laga Fault and an incipient development of a Tectonics secondary fault in the relay zone (where the 24 August hypocenter is located) without surface evidence (see point 4 in Figure 9).

On the other hand, this evidence along with the observed segment interactions and the more widespread deformed area in the MV sector (see section 4.4) suggest that the maximum throw could be related to the presence of a main structural barrier at depth. The barrier may likely coincide with the high-angle OAS thrust (below 5 km of depth) that prevents the natural free southward propagation and the fault linkage, enhancing the deformation through increment vertical displacement.

Conclusions

The multi-temporal analysis that we performed on the vertical displacements of the active faults The throw distributions pattern along the VBFS length of the coseismic (short-term) and post LGM (mid-term) displacements exhibited a similar, asymmetric shape. Thus, the Mt. Vettore sector experienced homothetic growth, with all the segments maintaining the same throw profile through time. This suggests a similar growth pattern over the last 18 kyr in the VBFS system notwithstanding with a different amount of displacement depending on the magnitude of the earthquake, as occurred for the 24 August and the 30 October 2016 events, as also observed in Tectonics paleoseismological studies [START_REF] Galadini | Paleoseismology of silent faults in the Central Apennines (Italy): The Mt. Vettore and Laga Mts. faults[END_REF][START_REF] Galli | The Awakening of the Dormant Mount Vettore Fault (2016 Central Italy Earthquake, M w 6.6): Paleoseismic Clues on Its Millennial Silences[END_REF][START_REF] Cinti | 22-kyr-Long Record of Surface Faulting Along the Source of the 30 October 2016 Earthquake (Central Apennines, Italy), From Integrated Paleoseismic Data Sets[END_REF]. In the Mt. Vettore sector, the rates at which this evolution occurred from the last 18 kyr were 1.65 ±0.5 mm/yr. If we assume this throw rate constant over time, and we consider the cumulated geological displacement, we can determine an age for this sector of around 200-250 kyr. This age can be interpreted as the onset of the faults in the Mt.Vettore western flank due to a southward shift of activity that produces the highest throws.

We interpreted the maximum displacements at mid and short-term at the southern tip of the system, as related to an ongoing linkage process with the Laga Fault. Several observations, including the sharp decrease in throw at the intersection between the Mt. Vettore sector and oblique structure of the OAS thrust, suggest that this inherited structure may also act as a barrier in this scenario. In this perspective also the origin of the Mt. Vettore fault and its very high slip rate could indicate that starting from ~200-250 kyr, the VBFS is trying to overcome the barrier. In this way, the barrier concentrates the stresses within the Mt. Vettore sector and prevents the southward lengthening of the system, which instead accommodates deformation through high throws. However, a small portion of the OAS thrust between 5 and 7 km depth appears to have been offset by the Mt. Vettore-Mt. Bove fault system. This phenomenon could be the first step to link the VBFS with the LF.

Furthermore, The good-to-perfect match between the short-and mid-term throw profiles showed that faults with post 18 kyr morphological evidence of activity are more prone to break in a future seismic event and should be considered as having a higher risk of rupturing in the seismic-hazard assessment. This suggests that an upper limit of fault activity of 18 kyr could be reasonable to discriminate active and capable faults, at least for similar morphological and seismotectonic contexts.

in particular ISIS and CEOS seismic pilot (ESA) programs. This work was supported by public funds received in the framework of GEOSUD, a project (ANR-10-EQPX-20) of the program "Investissements d'Avenir" managed by the French National Research Agency". P.P Pierantoni, B.

Pace, P. Boncio, L. Pousse, M. Rizza, A. Pasculli, and F. Mendez are greatly acknowledged for their help and support in the field and with the data treatment. We also thank Laura Gregory and Giancarlo Molli for their useful and perceptive comments that helped to improve the clarity and quality of the paper. Gran Sasso (GS) [START_REF] Calamita | Contrasting styles of fault reactivation in curved orogenic belts: Examples from the Central Apennines (Italy)[END_REF][START_REF] Di Domenica | Analogue modeling of positive inversion tectonics along differently oriented pre-thrusting normal faults: an application to the Central-Northern Apennines of Italy[END_REF]. The focal mechanism of the 1997 Colfiorito earthquake is from the CMT catalog [START_REF] Tectonics Dziewonski | Determination of earthquake source parameters from waveform data for studies of global and regional seismicity[END_REF][START_REF] Ekström | The global CMT project 2004-2010: Centroid-moment tensors for 13,017 earthquakes[END_REF]. The focal mechanisms of the 2009 to 2017 events are from the INGV web page (http://cnt.rm.ingv.it). Historical events (white circles) with their dates (AD) are from the CPTI15 catalog [START_REF] Rovida | CPTI15, the 2015 version of the Parametric Catalogue of Italian Earthquakes[END_REF] Inset: study area at a large scale. Modified after [START_REF] Perouse | Coseismic slip vectors of 24 August and 30 October 2016 earthquakes in Central Italy: Oblique slip and regional kinematic implications[END_REF]. The black dashed line is the morphological throw of the VBFS.

  Figure 4.a displays the geological throw distribution along the entire fault system. To compare the throw values among the long-, mid-and short-term datasets, we plotted the throw values that were measured on active faults (in this study, those with evidence of post-LGM activity). The lowest geological throws for faults having geomorphological evidence of activity (red faults in Figure 2.a) were in the southern portion of the VBFS (100-150 m for faults in the Mt. Vettore sector), whereas the central-northern sector of the VBFS showed higher values of 200-400 m at Mt. Porche and Mt. Bove. The maximum was at Mt. Bove, where the geological throw reached 400 m for a single fault and 800 m for the cumulative throw.

  Figure 4.b, where the fault segments are color-coded.Figure4.b shows the maximum throw at around 4-6 km on the transect line (MV sector), with an offset displacement of 24 m for a single segment that decreases towards the tip of the system to the south and reaches 5 m of throw 2-3 km northward. In the MP sector (7-13 km on the transect line), the vertical-slip distribution rises at a constant average value of 15-20 m for both synthetic and antithetic faults. In the MB sector (13-20 km on the transect line), a ~20-m peak sharply decreases to zero. Northward, the Ussita valley has no evidence of cumulative fault activity, whereas the CU sector (20-26 km on the transect line) has 10 m of maximum vertical displacement.

  thrust only in its shallowest and low angle portion, producing coseismic surface rupturing in the MV sector. In other words, this vertical propagation might have been confined in an area where the OAS thrust halted northward lateral propagation (Figure10.a). Despite the lithology that might control the slip propagation to the surface, minor surface ruptures can occur in the Laga Fm., as[START_REF] Vignaroli | Spatial-temporal evolution of extensional faulting and fluid circulation in the Amatrice Basin (central Apennines, Italy) during the Pleistocene[END_REF] suggested over the late Quaternary.The event on 30 October was modeled by[START_REF] Scognamiglio | Complex fault geometry and rupture dynamics of the MW 6.5, 30 October 2016, central Italy earthquake[END_REF] through strong-motion data (Figure10.b). The slip model was plotted on a 47°-dipping fault plane, highlighting rupturing that was confined above ~7 km depth. The slip propagated to both the north, where the rupture reached the surface at Mt. Bove and only affected the first 2 km, and the south, reaching the surface at Mt.

  (i.e., with post LGM activity) of the Mt. Vettore-Mt. Bove fault system (VBFS) characterized its spatial and temporal evolution. The 2016 seismic events ruptured the entire VBFS producing a maximum displacement in the southern sector of the Mt. Vettore sector. Our results, in agreement with[START_REF] Brozzetti | High-resolution field mapping and analysis of the August-October 2016 coseismic surface faulting (central Italy earthquakes): Slip distribution, parameterization, and comparison with global earthquakes[END_REF], showed that these maximum values of displacements localized in the south, are persistent at least over the last 18 kyr (post-LGM), and are mainly located on the faults on the western flank of the Mt.Vettore. While the basin boundary fault associated with the highest geological displacement has no evidence of recent ( Post-LGM) activity.On the contrary, the active faults display the highest geological displacement related to the onset of extension (i.e. 1.1-1.2 Myr) in the central northern sectors of the VBFS, at the Mt. Bove sector.

Figure 2 .

 2 Figure 2. a) Geological map of the VBFS in the Central Apennines; see Figure 1 for the location. Modified after Pierantoni et al. (2013): Calcare massiccio Fm. (MAS), Bugarone Fm. (BU), Corniola Fm. (COI), Rosso Ammonitico Fm. (RSA), Calcari a Posidonia Fm. (POD), Marne del Serrone Fm. (MSE), Calcari Diasprigni Fm. (CDU), Maiolica Fm. (MAI), Marne a Fucoidi Fm. (FUC), Scaglia Bianca Fm. (SBI), Scaglia Rossa Fm. (SAA), Scaglia Variegata Fm. (VAS), Scaglia Cinerea Fm. (SCC), and Laga Fm. (LAG). The dashed lines are the cross-section traces (in the supplementary Figure S5). The structural symbols are the same as those in Figure 2.b. b) Shaded relief map of the VBFS from a 10 m-resolution DEM. The red stars indicate the locations of the three 2016 mainshocks with their focal mechanisms. The blue transect line indicates the fault system's average strike of N150° and the main sectors of the system: Mt. Vettore (MV), Mt. Porche (MP), Mt. Bove (MB) and Cupi-Ussita (CU). The active normal faults (solid red lines) are faults that ruptured during the 2016 earthquakes and showed morphological evidence on the topography. The inferred active normal faults (red dashed lines) are faults with morphological evidence that did not rupture in 2016.

Figure 3 .

 3 Figure 3. a) Characteristic features of fault scarps that were used for measurements on highresolution topographic profiles. The topographic offset (To) for each profile is the vertical separation between two portions of a unique marker surface (with slope β) that was displaced by a fault (with dip angle α). b) Components of a net-slip vector on the fault plane. The fault down-throw (Tr) is the projection on a vertical plane of the net-slip vector. See the text for an explanation of the Tr evaluation. The degraded scarp and colluvial wedge are the results of erosion processes that smooth the fault scarp over time.

Figure 4 .

 4 Figure 4. Throw along-strike at three timescales for VBFS. Location of measurements indicated by red squares placed on the projected position along the Transect line. Dashed faults indicate faults with no available data but with throws (at long/mid/short term) > 0. A grey area defines cumulative total displacement for each position along the Transect line (both east and west-dipping faults). a)

Figure 5 .

 5 Figure 5. Downthrow and slip components values (net, dip and strike-slip components) in MtVettore area for each segment. The measured rake at each site is also displayed. The strike-slip component is always small with respect to dip-slip portion, and downthrow is not affected by the strike-slip component (see the supplementary for the data locations).

Figure 6 .

 6 Figure 6. Cumulative throw vs coseismic throw diagram. The thick red line defines the proportional envelope between the two datasets. The thinner lines are related to the trends of each fault segment and are color-coded according to the corresponding segments. The colored data indicate orange MV1 fault, light-blue MV2 fault, purple MV4 fault, and grey MV5 fault.

Figure 7 .

 7 Figure 7. Map of the throw evolution through time: a) short-term throw, b) mid-term throw, c) long-term throw. The color scales show the range of vertical displacement at each time frame. d) Cumulative displacement profile at each time scale (synthetic plus antithetic faults). The red point indicates the maximum throw position: in the mid-term, there is a southward migration of this point.

Figure 8 .

 8 Figure 8. Correlation among a) short-term throw, b) mid-term throw, and c) throw of the penultimate event found in the trenches excavated in segments MV5 (Galadini e Galli, 2003), MP4 (Cinti et al., 2019) and MP5 (Galli et al., 2019); d) summary of the timing events, modified from Cinti et al., (2019). The values shown in panels a) and b) are related to the data where the trench has been dug (i.e. MP5.1, MP 4.1, MV 5.3).

Figure 9 .Figure 10 .

 910 Figure9. Block diagram that shows the relationships between the VBFS and OAS and the locations of the 2016 mainshock hypocenters at depth (from[START_REF] Chiaraluce | The 2016 central Italy seismic sequence: A first look at the mainshocks, aftershocks, and source models[END_REF] along the fault plane (simplified as a single and long plane). (1) Southernmost MV sector, which recorded the highest throw of the system during the last 18 kyr. This feature reflects the prominent southward evolution of the system, which is inhibited by the presence of a major barrier at depth: the OAS thrust ramp.Thus, the fault system accumulates higher displacement. (2) To the south, the VBFS intersects the OAS thrust ramp at depth, which is cross-cut in its shallowest portion (first 2 km from[START_REF] Porreca | Seismic reflection profiles and subsurface geology of the area interested by the 2016-2017 earthquake sequence (Central Italy)[END_REF] 2020; see T1). (3) To the north, the VBFS intersects, and it is rooted on the OAS thrust ramp. (4) South of the VBFS, no evidence of clear surface faulting is observed, even though the 24 August event revealed the presence of a fault at depth. We interpret this zone as a relay between the VBFS to the north and LF to the south. (5) The throw deficit at all time scales in the Ussita valley to the south of the CU sector. (6) Complex fault zone of barrier (see text).

  Our new unpublished data used in this work are available in the Supporting , and references therein. The study area (blue rectangle) is the Mt. Vettore-Mt. Bove fault system (VBFS). The other faults are the Laga Fault (LF) and Gorzano Fault (GF). The main Neogene thrusts are shown in grey: Valnerina Line (VL), Olevano-Antrodoco-Sibillini (OAS), and

	(2016)
	Information,	while	all	the	other	data	are	contained	in	the	repository:
	doi.pangaea.de/10.1594/PANGAEA.920893. It contains information © CNES (2016), Distribution
	Airbus DS, all rights reserved.

Acknowledgments

This work has been funded by the Italian Ministry for Education, University and Research (MIUR) (ex 60% grants to A. Pizzi), by the LABEX OT MED and by INSU. CNES is warmly acknowledged for providing us with the Pleiades satellite images immediately after the events and