Pattern Of Active Deformation Research Articles

Morphometric analysis of the North Liuleng Shan Fault in the northern Shanxi Graben System, China: Insights into active deformation pattern and fault evolution

The North Liuleng Shan Fault (NLSF) is one of the major active faults in the northern Shanxi Graben System (SGS) in North China. Although the fault has been investigated extensively in terms of late Quaternary activity, its active deformation pattern is still poorly characterized. In this study, we conducted a morphometric analysis of the fault using various geomorphic indices to assess the along-strike relative uplift rates, which include basin relief, slope, mountain front sinuosity (Smf), hypsometric integral (HI) and curves, valley floor width-to-height ratio (Vf), asymmetry factor (Af), basin elongation ratio (Re), and normalized channel steepness indices (ksn). Our findings indicate that the central portion of the fault has experienced higher relative uplift rates than the southwestern and northeastern portions, as demonstrated by higher basin-averaged slopes and ksn values, and lower Vf, Re, and Smf values. This spatial distribution pattern of relative uplift rates appears to correlate well with along-strike changes in the fault geometry and kinematics of the NLSF. We interpret the EW-striking, central portion of the NLSF as a releasing bend formed by the NE-striking, right-stepping, en-echelon southwestern and northeastern portions of the fault system, which are characterized by right-lateral oblique slip. Furthermore, the northeastward increase in HI values along with the regional basin evolution history suggest that the NLSF likely propagated from southwest to northeast. We propose that the southwestern portion of the fault most probably initiated earlier and that the central and northeastern portions formed later as extensional structures at the termini of the fault zone. Our findings contribute to a better understanding of the tectonics and genesis of the basin-and-range geomorphology in the northern SGS.

Active Deformation Pattern in the Western Flank of the Central Taurides, Southern Margin of the Central Anatolian Plateau: Inferences From Geomorphic Markers and Kinematic Indicators

AbstractThe southwestern margin of the Central Anatolian Plateau corresponds to the upper crust of the subduction between African and Anatolian plates, with a high relief of up to 2 km. This mountainous region has distinctive geomorphological features and presents a unique setting to investigate the mechanism of orogenic plateau margin development related to subduction and topographic evolution around the Eastern Mediterranean. We present new kinematic data from exposed fault planes and tectonic landforms from high‐resolution digital elevation models to elucidate the deformation pattern and its relation with the crustal deformation. We evaluate the deformation pattern based on the spatial distribution of kinematic analyses and geomorphic markers like low relief upland surfaces, disrupted karst basins, knickpoints, and deep bedrock incisions from watershed to shoreline. Our geomorphic analysis reveals a post‐orogenic transient actively deforming topography. The geomorphic markers constrain long‐term surface uplift pattern with a mean cumulative surface uplift of 1,710 ± 50 m and shows an increasing trend from west to east, from 1,600 ± 50 to 1,800 ± 50 m. Our results suggest a dome‐like uplift pattern in the west‐east direction across the southern margin that reaches up to maximum cumulative uplift values in the quadrangle of Alanya‐Başyayla‐Ermenek‐Gazipaşa. Our kinematic measurements along the youngest generation of faults revealed an active NE‐SW extensional deformation across a broad 200 km zone in the north of the subduction. Our findings have significant implications for understanding the morphotectonic evolution and post‐orogenic deformation in the plateau margins and geodynamic evolution of the Eastern Mediterranean.

Distribution of active tectonics in the Himalayan piedmont (Darjeeling, eastern India) inferred from Horizontal‐to‐Vertical spectral ratio analysis of passive seismic records

AbstractThe pattern of active deformation of frontal structures in Darjeeling Himalaya is complex with out‐of‐sequence reactivations in the chain and development of scarps associated with earthquake ruptures reaching the surface in the piedmont. To clarify the distribution of active deformation in this area, we analyse passive seismic records by the Horizontal‐to‐Vertical Spectral Ratio method along three NS trending profiles. We image the Siwalik sedimentary rocks / recent deposits interface under the piedmont and show folded and faulted geometries. Two of these faults are located under scarps of about 10 m affecting the 3.7 ± 0.7 ka old surface of the Tista megafan. Such features imply that about half of the convergence is expressed south of the Himalayan front while the other part occurs out‐of‐sequence in the chain, suggesting a very limited activity of the Main Frontal Thrust itself.

Delineation of tectonically active zones in the Island Belt Uplift region, Kachchh Basin, western India: A geomorphic and geodetic approach

In the present study, we have identified the tectonically active zones along the Island Belt Uplift (IBU), an upthrown block of E-W trending Island Belt Fault (IBF). Major and minor transverse faults have segmented the IBU into four sub-uplifts, viz. Pachham Uplift (PU), Khadir Uplift (KU), Bela Uplift (BU), and Chorar Uplift (CU) from west to east, respectively. The work includes geodetic and morphotectonic analysis of the IBU region. The Normalized Steepness Index (Ksn) analysis was performed supported by swath profiling to mark the tectonic activity variations along and across the strike of the IBF in the IBU region. Further, the Ksn contour map was prepared by using a power-law function of slope (S) of the longitudinal profiles of the river, concavity index (ө), and upstream area (A), which is an integral part of the Stream Power Incision Model (SPIM). The Ksn analysis suggests that the maximum amount of tectonic activity is restricted along the northern escarpment of the IBU, which falls in the vicinity of IBF and it's associated longitudinal and transverse faults. Based on the results of Ksn analysis, we have marked the tectonically active zones in the IBU region, which shows that amongst four sub-uplifts, the PU and BU were found most active (Zone-I), the KU expresses moderate activity (Zone-II), while CU demonstrated to be least active (Zone-III). The results were also confirmed by documentation of active tectono-geomorphic features like strath terraces, river offsets, straight fault scarps, triangular facets, linear valleys, fault ridges, Quaternary upwarps, laterally displaced crests and alluvial fans within the IBU. The active deformation pattern calculated using the Global Positioning System (GPS) data-set from 2009–2019 along IBU reveal maximum deformation rate of ∼2.5 ± 0.5 mm/yr in the PU, ∼2.0 ± 0.5 mm/yr in the BU while, the KU shows the deformation rate of ∼1.2 ± 0.5 mm/yr, which coincides well with the results of Ksn. The Ksn analysis results were also validated by comparing them with existing Gradient Length Anomaly (GLA) and Differential Interferometric Synthetic Aperture Radar (DInSAR) data. The ongoing tectonic activity in the study area is also manifested by the occurrence of moderate seismic activities in the identified active zones. The active tectono-geomorphic features and fault scarp geometry were analyzed and compared with the existing experimental models of basement fault and overlying sedimentary covers, which allow us to understand the nature of fault components of IBF. The analysis reveals that the IBF has been influenced by both dip-slip and strike-slip fault components of motion, which can be further confirmed by geophysical analysis. The results of Ksn analysis and field evidence were merged to prepare Active Fault Map of the IBU region that can be implemented for future seismic hazard assessment.

Estimation of regional surface deformation post the 2001 Bhuj earthquake in the Kachchh region, Western India using RADAR interferometry

The key objective of the present study is to estimate the surface displacement and to understand/monitor the active deformation pattern in the Kachchh region post the 2001 Bhuj Earthquake by implementing the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSI) and Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques. We employed the ENVISAT ASAR (15 images), ALOS PALSAR (6 pairs) and SENTINEL-1A (117 images) data sets acquired during the periods 2003–2005, 2007–2009, and 2016–2020 respectively. The PSI results of the Envisat dataset reveals that the Kachchh mainland region has undergone an average surface deformation of ± 22 mm/yr during 2003–2005. The maximum displacement observed from the ALOS PALSAR data sets (Window-1 to 6) during the period 2007–2009 is ∼ ± 1.2 cm. Further, the ground displacement observed from the Sentinel-1A dataset during the period 2016–2020 is ±16 mm/yr for the west-central region and 6 mm/yr uplift and 8 mm/yr subsidence in the eastern Kachchh mainland region. Surprisingly, high rate of deformation is detected towards the Pachham Island, Banni, Rann and the eastern region of the Kachchh after the 2001 Bhuj event. Correlating the results of different data sets, it is concluded that the deformation is high near the vicinity of the fault zones indicating the tectonically active nature of the faults. From the obtained results, we infer that, post the 2001 Bhuj earthquake, the surface displacement in the Kachchh mainland region is escalated till 2009 which is due to continuous aftershock activity and then started declining because of the ongoing seismic settlement. The acquired deformation rates are correlating well with the GPS derived displacement rates. Further, our results will assist in accurately demarcating the extent of the fault zones and also helps in precisely marking the areas undergoing active deformation, which will aid in micro zonation studies, mitigation planning and also for the preparation of an active tectonic map for the region.

Deformation Pattern of the Northern Sector of the Malta Escarpment (Offshore SE Sicily, Italy): Fault Dimension, Slip Prediction, and Seismotectonic Implications

Marine seismic reflection data coupled with on-land structural measurements improve our knowledge about the active deformation pattern of the northern sector of the Malta Escarpment, a bathymetric and structural discontinuity in the near-offshore of Eastern Sicily. As favourably oriented to be reactivated within the Neogene Africa–Europe convergence, it is believed that the Malta Escarpment has a significant role in the recent seismotectonic framework of the Western Ionian Basin and the Hyblean foreland domain of SE Sicily, where some of the largest and most destructive Mediterranean earthquakes are located according to available historical catalogs. Offshore seismic data along with bathymetric grids illuminate the shallow subseafloor setting and allow more accurate mapping of the seafloor expression of previously identified faults in the area. The seismic interpretation and the near-fault sediment pattern analysis provide constraints on fault 3D geometries as well as on their through-time tectonic activity, suggesting also that part of the observed deformation may have been caused by nontectonic processes. Identified faults form currently an E-dipping, roughly N–S trending, and 60 km-long extensional belt deforming the seafloor with a significant displacement amount in the Ionian offshore between Catania and Siracusa. 3-dimensional parameters of faults were then used to derive expected magnitudes and their reactivation propensity. Empirical scaling relationships and forward methods point to a high seismic potential for the detected fault as well as predict the fault slip behavior according to the field-derived differential stress. This combined analysis along with faults displacement measurements pointed out how the longest and most continuous fault could be capable of generating M > 7 seismic events, putting forward strong seismotectonic implications for the adjacent and densely populated Hyblean Plateau. The expected magnitude and the estimated recurrence time interval are compatible with those inferred for large historical earthquakes in the area even if other offshore seismic sources cannot be ruled out.

Structural architecture and active deformation pattern in the northern sector of the Aeolian-Tindari-Letojanni fault system (SE Tyrrhenian Sea-NE Sicily) from integrated analysis of field, marine geophysical, seismological and geodetic data

Framed in the current geodynamics of the central Mediterranean, the Aeolian-Tindari-Letojanni fault system is part of a wider NW-SE oriented right-lateral wrench zone which accommodates diverging motion between regional-scale blocks located at the southern edge of the Calabrian Arc. In order to investigate the structural architecture and the active deformation pattern of the northern sector of this tectonic feature, structural observations on-land, high and very-high resolution seismic reflection profiles, swath bathymetry and seismological and geodetic data were merged from the Lipari-Vulcano volcanic complex (central sector of the Aeolian Islands) to the Peloritani Mountains across the Gulf of Patti. Our interpretation shows that the active deformation pattern of the study area is currently expressed by NW-SE trending, right-transtensional en-echelon fault segments whose overlapping gives rise to releasing stepover and pull-apart structures. This structural architecture has favored magma and fluid ascent and the shaping of the Lipari-Vulcano volcanic complex. Similarly, the Gulf of Patti is interpreted as an extensional relay zone between two overlapping, right-lateral NW-SE trending master faults. The structural configuration we reconstruct is also supported by seismological and geodetic data which are consistent with kinematics of the mapped faults. Notably, most of the low-magnitude instrumental seismicity occurs within the relay zones, whilst the largest historical earthquakes (1786, Mw=6.2; 1978, Mw=6.1) are located along the major fault segments.

Late Quaternary tectonics and active ground deformation in the Catania urban area (eastern Sicily): New constraints from a geological investigation

New surface and subsurface geological data on the Catania urban area, in eastern Sicily, are here illustrated by a detailed geological map of the city and by four significant cross-sections. Our study aims at defining the prolongation of the principal regional Late Quaternary tectonic features, beneath the city. The resulting geometry of the investigated structures completes the tectonic pictures of two different stages of deformation. The earlier structural association, ranging in age from 600 to 125ka, consists of a transpressive dextral belt that include E-W oblique thrust ramp, located to the south and the north of the city respectively, connected by a wide NE-SW oriented anticline crossing the urban area. The younger structural association developed since the Late Pleistocene and includes a set of ENE-trending folds that originated at the hangingwall of a main thrust ramp running just beneath the old town (Catania Thrust Ramp). These contractional features have been active during the last 60ka and their geometry is consistent with the active ground deformation observed by the available geodetic data (GPS vectors and DInSAR analyses). The entire set of the recent structures are bordered to the north by a dextral transfer zone, reactivating part of the previous E-W alignment, that now represents the tectonic boundary with the Mt. Etna Volcano transtensional domain. Our data suggest that the Catania Thrust Ramp could play a main role in the active deformation pattern of the region, thus representing a potential seismotectonic feature to be carefully investigated for the re-evaluation of the seismic hazard of the area.

Active faulting and continental slope instability in the Gulf of Patti (Tyrrhenian side of NE Sicily, Italy): a field, marine and seismological joint analysis

The Gulf of Patti and its onshore sector represent one of the most seismically active regions of the Italian Peninsula. Over the period 1984–2014, about 1800 earthquakes with small-to-moderate magnitude and a maximum hypocentral depth of 40 km occurred in this area. Historical catalogues reveal that the same area was affected by several strong earthquakes such as the Mw = 6.1 event in April 1978 and the Mw = 6.2 one in March 1786 which have caused severe damages in the surrounding localities. The main seismotectonic feature affecting this area is represented by a NNW–SSE trending right-lateral strike-slip fault system called “Aeolian–Tindari–Letojanni” (ATLFS) which has been interpreted as a lithospheric transfer zone extending from the Aeolian Islands to the Ionian coast of Sicily. Although the large-scale role of the ATLFS is widely accepted, several issues about its structural architecture (i.e. distribution, attitude and slip of fault segments) and the active deformation pattern are poorly constrained, particularly in the offshore. An integrated analysis of field structural geology with marine geophysical and seismological data has allowed to better understand the structural fabric of the ATLFS which, in the study area, is expressed by two major NW–SE trending, en-echelon arranged fault segments. Minor NNE–SSW oriented extensional structures mainly occur in the overlap region between major faults, forming a dilatational stepover. Most faults display evidence of active deformation and appear to control the main morphobathymetric features. This aspect, together with diffused continental slope instability, must be considered for the revaluation of the seismic and geomorphological hazard of this sector of southern Tyrrhenian Sea.

New heat flow determination in northern Tarim Craton, northwest China

Tarim Craton is a Precambrian block situated in northwest China, just north of the Tibetan Plateau, where a large sedimentary basin with abundant hydrocarbon potential has developed. Accurate heat flow data for Tarim is vital for understanding the lithospheric evolution and hydrocarbon generation in this area; however, there were unavailable until now, due to a lack of high quality steady-state temperature logging data. Here, we report 10 new heat flow values derived from steady-state temperature logging and measured thermal conductivity data. New heat flow values range from 40.1 to 49.4 mW m−2, with a mean of 43.1 ± 3.0 mW m−2. In addition, radiogenic heat production from the sediments accounts for 20 per cent of the observed surface heat flow, whilst the mantle heat flow is estimated to be as low as 6–15 mW m−2; this indicates a dominant contribution from crustal heat, to the observed heat flow. The average heat flow and crustal temperature in the Tarim Craton are markedly lower than those in the Tibetan Plateau, whilst the calculated rheological strength of the lithosphere, beneath Tarim, is sufficiently large to resist the elevation-induced gravitational potential energy difference between Tarim and Tibet. This inherited thermal and rheological contrast, between the craton and Plateau, can be traced back to before the India–Asia collision; this accounts for the differential active deformation pattern in the Tarim Craton and adjacent areas.

Evidence for an active shear zone in southern Nevada linking the Wasatch fault to the Eastern California shear zone

Previous studies have shown that ~5% of the Pacifi c‐North America relative plate motion is accommodated in the eastern part of the Great Basin (western United States). Near the Wasatch fault zone and other nearby faults, deformation is currently concentrated within a narrow zone of extension coincident with the eastern margin of the northern Basin and Range. Farther south, the pattern of active deformation implied by faulting and seismicity is more enigmatic. To assess how present-day strain is accommodated farther south and how this relates to the regional kinematics, we analyze data from continuous global positioning system (GPS) stations and model the strain rate tensor fi eld using the horizontal GPS velocities and earthquake focal mechanisms. The results indicate an ~100-km-wide zone of ~3.3 mm/yr extension at 40.5°N that broadens southward from the Wasatch fault zone to a width of >400 km at 36°N. This broadening involves at least one zone of localized extension in northwestern Arizona that encroaches into the southwestern plateau, and an eastnortheast‐trending sinistral shear zone (the Pahranagat shear zone) through southern Nevada. This shear zone may accommodate as much as 1.8 mm/yr, and is a key feature that enables westward transfer of extension, thereby providing a kinematic connection between the Wasatch fault zone and the Eastern California shear zone.

Recent and active deformation pattern off the easternmost Algerian margin, Western Mediterranean Sea: New evidence for contractional tectonic reactivation

We describe for the first time a set of large active thrusts and folds near the foot of the easternmost Algerian margin, Western Mediterranean, from swath bathymetry and high-resolution seismic data acquired in 2005 during the Maradja2/Samra cruise. This active system resumes a previous passive margin and creates growth strata deposition on the limbs of large folds, resulting in the development of perched basins at the foot of the margin since less than ~ 1 Ma. They form a set of overlapping fault segments verging toward the Algerian basin, in a way similar to what has been observed off eastern Algiers on the rupture zone of the 2003 Mw 6.8 Boumerdes earthquake. The horizontal shortening rate across large folds is estimated to be of the order of 1 mm/yr. Although no historical earthquakes are reported here, these fault segments could have been responsible for large ( M ~ 7.5) events in the past. This young tectonic system further supports the hypothesis of subduction inception of the Neogene oceanic lithosphere in the context of the Africa–Eurasia convergence.

Influence of mantle dynamics on the topographic evolution of the Tibetan Plateau: Results from numerical modeling

We investigate numerically the evolution of crustal and lithospheric thickness, thermal structure, topography, and strain rate of the Tibetan Plateau through time, using the thin viscous sheet approach. We show that lithospheric mantle must have been removed from beneath Tibet to explain the present surface elevation and lack of regional surface slope. In the absence of this removal, the modeled topography reaches a maximum elevation of <4000 m (for weak rheology), or the surface slopes significantly northward (for strong rheology). The crust must have been warmed and weakened by an increase of radiogenic heat production at depth due to crustal thickening. In the absence of this warming, viscous stresses associated with plate convergence exceed stresses produced by topography, and the present pattern of vertical thinning and east‐west extension would not have developed. Continuous removal of lithosphere, by delamination or convection, does not allow sufficient crustal warming and fails to reproduce either the present topography or the pattern of active deformation on the plateau in a reasonable time. Geologically rapid removal of the lithospheric root beneath the thickened crust of Tibet successfully explains the current elevation of the plateau, its lack of surface slope, the steep south and north margins, and the pattern of the present deformation, including vertical thinning, E‐W extension, and extrusion and vertical axis rotation on the eastern margin. Our modeling suggests that this removal took place within the last 12 m.y.

Active faulting in the western Pyrénées (France): Paleoseismic evidence for late Holocene ruptures

We have identified a 50-km-long active fault scarp, called herewith the Lourdes Fault, between the city of Lourdes and Arette village in the French Pyrénées. This region was affected by large and moderate earthquakes in 1660 (Io = VIII–IX, MSK 64,), in 1750 (Io = VIII, MSK 64) and in 1967 ( M d = 5.3, Io = VIII, MSK 64). Most earthquakes in this area are shallow and the few available focal mechanism solutions do not indicate a consistent pattern of active deformation. Field investigations in active tectonics indicate an East–West trending and up to 50-m-high fault scarp, in average, made of 3 contiguous linear fault sub-segments. To the north, the fault controls Quaternary basins and shows uplifted and tilted alluvial terraces. Deviated and abandoned stream channels of the southern block are likely due to the successive uplift of the northern block of the fault. Paleoseismic investigations coupled with geomorphic studies, georadar prospecting and trenching along the fault scarp illustrate the cumulative fault movements during the late Holocene. Trenches exhibit shear contacts with flexural slip faulting and thrust ruptures showing deformed alluvial units in buried channels. 14C dating of alluvial and colluvial units indicates a consistent age bracket from two different trenches and shows that the most recent fault movements occurred between 4221 BC and 2918 BC. Fault parameters and paleoseismic results imply that the Lourdes Fault and related sub-segments may produce a M W 6.5 to 7.1 earthquake. Fault parameters imply that the Lourdes Fault segment corresponds to a major seismic source in the western Pyrénées that may generate earthquakes possibly larger than the 1660 historical event.

Active extension in Val d'Agri area, Southern Apennines, Italy: implications for the geometry of the seismogenic belt

SUMMARY Integration of geologic, geomorphologic and seismologic data sets is used to reconstruct the recent tectonic evolution and active deformation pattern in the Val d'Agri area, located in the seismically active axial sector of the Southern Apennines (Italy). The western portion of the Apennines thrust belt has been affected by Pliocene–Quaternary extension during easterly roll-back and crustal delamination of the Adriatic slab. The bulk of Quaternary extension has been accommodated by SW-dipping oblique and normal faults, which have attained mature morphologic and structural features and, nowadays, separate mountain ranges from intermontane basins. However, in the present seismogenic belt, coseismic faulting locally occurs on NE-dipping structures, which might cut the inherited Pleistocene landscape. In the Val d'Agri basin, in spite of the large Early–Middle Pleistocene, displacement occurred on SW-dipping faults bordering its eastern flank, our investigations show that the recent basin evolution has been controlled by a NE-dipping fault system (Monti della Maddalena fault system, MMFS). This fault system cuts across the Monti della Maddalena range, west of the Agri valley and has not yet created an evident tectonic landscape. Notwithstanding, fault motion since the Middle Pleistocene might explain geomorphologic and hydrographic anomalies of the Agri river and its valley, where fault-controlled subsidence has captured the river course and produced an aggrading plain within a regional uplift context. Recent and ongoing motion is documented by fault scarplets in loose deposits, 14C ages of palaeosols and the spatial relation with low to moderate instrumental seismicity. Results from fault kinematic analysis are compatible with fault-plane solutions of local and regional seismic events, and indicate ∼NE–SW oriented extension. Recognition of the MMFS as a potential seismogenic fault increases the longitudinal extent of the NE-dipping, morphologically immature seismic sources in the Southern Apennines and argues against the range-bounding fault model for active extension in the region. The regional size of the NE-dipping seismogenic belt may result from impingement of a mantle wedge beneath the Apenninic chain and possibly track the external front of crustal delamination.

Heat flow pattern and lateral variations of lithosphere strength in China mainland: constraints on active deformation

On the basis of 723 heat flow measurements in China mainland and over 1500 data adopted from the global heat flow data set (cf. [Rev. Geophys. 31 (1993) 267]), we compiled the heat flow map of China mainland and its adjacent area, to exhibit overall variation of heat flow pattern in China mainland. Nineteen profiles of lithospheric strength were constructed for representative tectonic units. Significant difference exists between eastern and western China in spatial pattern of heat flow. Divided by 105°E meridian, heat flow values in eastern China show a westward decreasing trend; and a northward variation is observed in western China. The lateral variation in lithospheric strength corresponds to the heat flow variation, and there is a generally reverse relation between heat flow and lithospheric strength in China mainland. The lithospheric strength of Tibet is much lower than its neighboring regions due to a thick crust. The mosaic pattern of active deformation in China mainland results from lateral rheological heterogeneity. The very weak lower crust beneath high heat flow belts may play an important role in the present deformation processes. The good coincidence between low strength domains and active seismic zones demonstrates the intrinsic relation between strength heterogeneity and regional seismicity pattern in China mainland.

Active crustal extension in the Central Apennines (Italy) inferred from GPS measurements in the interval 1994–1999

We present the first GPS estimate of crustal extension in the central Apennines (Italy) through the analysis of the deformation of a sub‐network of the National GPS Geodetic network IGM95 in the interval 1994–1999. The selected sub‐network spans the entire active deformation belt perpendicularly to its axis and allows the evaluation of (1) the total extension rate absorbed in this sector of the Apennines and (2) the seismogenic potential of the normal faults active in the Late Pleistocene‐Holocene interval within the network. Results of this reoccupation are consistent with an extensional strain rate of 0.18 × 10−6 yr−1 concentrated in an area of about 35 km width, giving an average extension rate of 6±2 mm/yr across the central Apennines. The pattern of active deformation suggests active elastic strain accumulation on the westernmost of the two fault systems active in the Late Pleistocene‐Holocene interval and may also suggest the presence of another active fault system not recognized so far.