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Geologic sections across the Mt. Gorzano normal fault (location in fig. 7) and diagram illustrating the along-strike variation of the vertical component of net geological displacement.
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We present a seismotectonic study of the Amatrice-Campotosto area (Central Italy) based on an integrated analysis of minor earthquake sequences, geological data and crustal rheology. The area has been affected by three small-magnitude seismic sequences: August 1992 (M=3.9), June 1994 (M=3.7) and October 1996 (M=4.0). The hypocentral locations and f...
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Context 1
... al., 1991;Cacciuni et al., 1995;Vezzani and Ghisetti, 1998), we measured the total fault displacement along 11 cross sections, orthogonal to the fault strike, by correlating ho- mologous stratigraphic markers at the hanging wall and footwall blocks and assuming constant thickness of the lithological units separated by the stratigraphic markers ( fig. 8). The strati- graphic markers used are the top of the Cer- rogna and Pteropodi Marls formations and the stratigraphic contacts among the different litho- logical associations of the Laga formation (are- naceous, arenaceous-pelitic and pelitic-arena- ceous associations, Centamore et al., 1991). The highest displacement (up to 2300 m) was ...
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... of the oldest syntectonic deposits accumulated in the Ama- trice continental basin according to Blumetti et al. (1993). By assuming the onset of the Mt. Gorzano Fault activity at the base of Early Pleis- tocene (last 1.8 Myr), we obtain an average throw rate of ∼1.3 mm/yr along the cross section showing the maximum downthrow (section 4, 2300 m; fig. 8). Blumetti et al. (1993) reported that both the pebbles and the matrix of the Early Pleistocene glacis deposits of the Amatrice Basin derive al- most exclusively from erosion of the Laga for- mation; the absence of clastic elements from the Cerrogna Marls formation suggests that the Cerrogna Marls were not exposed during the ...
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... The available morphotectonic and paleoseismologic data ( Bachetti et al. 1990;Galadini and Galli, 2000;Galadini and Messina, 2001) clearly indicate that the fault is active, i.e. it has an established record of activity in the Late Quaternary (see Machette, 2000 for a dis- cussion on terminology). An interpretation of the displacement profile in fig. 8 may help to ex- plain why the strongest and clearest evidence of Late Quaternary activity is mainly located in the southern portion of the structure, rather than in the central part (i.e. close to the maximum dis- placement) as one would expect for an isolated fault. The displacement profile is asymmetric, with a steeper gradient in ...
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Present‐day convergence between Caribbean and North American plates is accommodated by subduction zones, major active thrusts and strike‐slip faults, which are probably the source of the historical large earthquakes on Hispaniola. However, little is known of their geometric and kinematic characteristics, slip rates and seismic activity over time. T...
Citations
... In this work we studied the Gorzano normal fault (Boncio et al., 2004a(Boncio et al., , 2004bValoroso et al., 2013;Chiaraluce et al., 2017;Falcucci et al., 2018;Cheloni et al., 2019;Michele et al., 2020;Barchi et al., 2021;Buttinelli et al., 2021) located in the overlap zone between the SSE termination of the AVN sequence and the NNW portion of the AQ sequence ( Fig. 1). ...
... In this interpretation the seismicity recorded during AQ 2009 and AVN 2016 sequences is occurring along an inherited normal fault located in the footwall of the thrust that is not connected with the mapped GF at the surface (Buttinelli et al., 2021). In marked contrast, a continuity of the GF from the surface into the seismogenic layer (as a single structure) is proposed by the integration of structural and morphotectonic features with three small magnitude seismic sequences M < 4, occurred in the area between 1992 and 1996 (Boncio et al., 2004a(Boncio et al., , 2004b. This interpretation is consistent with geomorphological analyses coupled with seismological and geodetic data related to the AQ 2009 and AVN 2016 sequences (Falcucci et al., 2018), with a different seismic reflection profiles interpretation (Barchi et al., 2021) and supported by paleoseismological studies documenting a maximum magnitude of ~6.6 for the GF (Galadini and Galli, 2003). ...
... The φ = 0.58 obtained in our analysis is consistent with previous works conducted in this area like Boncio et al., 2004b) for the 1992-1994-1996 Campotosto sequences; Chiaraluce et al., 2003) for the 1997 Colfiorito sequence (subvertical σ1, σ2 subhorizontal and oriented along the strike of the fault system (NW-SE) and a subhorizontal σ3 trending NE-SW, resulting in φ = 0.6.) and (Ferrarini et al., 2015) for the 2009 L'Aquila sequence (Table 1). From φ we can generate the normalized slip-tendency NT s stereo-plot ( Fig. 6b and details in Morris et al., 1996 andTrippetta, 2007). ...
... After the 1997 seismic events, the Umbria-Marche Apennines (central Italy) has become a subject of great scientific interest and many studies have been carried out on the seismic hazard of the area (e.g., Boncio et al. 2004a, b;Pizzi et al. 2002Pizzi et al. , 2017Pantosti et al. 2012;Tondi 2000;Tondi et al. 2009), as well as on the main causative faults, and the evolution of the three main seismic sequences (Amato et al. 1998;Chiarabba et al. 2009;Chiaraluce et al. 2017). Historically, the portion of the Marche Region immediately north of the area hit by the aforementioned seismic sequences was the epicentral area of strong earthquakes. ...
The determination of ground motion is crucial to plan the appropriate emergency activities, especially in areas characterised by an intense seismic history like the Italian peninsula. Ground motion assessment is generally based on the seismological parameters reported in the instrumental and parametric seismic catalogues. Therefore, the computation of shaking scenarios of historical earthquakes is very challenging, due to the poorly constrained variables (i.e., magnitudes, epicentral location, seismogenic sources), derived from the macroseismic intensity. In this study, we propose a novel approach to investigate the location and parametrization of the seismogenic sources of historical earthquakes and derive shaking scenarios. To this aim, the ground motion of two historical events, the Fabriano (1741, Mw = 6.1, Imax IX MCS) and Camerino (1799, Mw = 6.1, Imax IX–X MCS) earthquakes is simulated. In order to include the site response, a Vs,30 map of the Umbria and Marche regions is created from near-surface data. Different causative faults solutions are tested, finally discussing the ideal seismogenic source based on the residual analysis between observed and simulated macroseismic intensities. The resultant shaking scenarios of the two events are obtained by integrating observed intensities and simulations.
... The inversion depends on the starting model and initial hypocenters, so a trial-and-error procedure is necessary (Kissling et al. 1994). We used a wide range of starting models, beginning with a random velocity value for the surface and a random velocity gradient, resulting in several realistic and unrealistic models, as suggested by Boncio et al. (2004). A total of 1000 randomly generated starting models were produced, with a layer thickness of 1 km and a depth extent to the approximate Moho depth of 30 km. ...
The Leipzig-Regensburg fault zone is documented as a band of seismic activity extending northwards from the earthquake swarm region NW-Bohemia/Vogtland at the Czech-German border area and is intersected by several Hercynian fault zones. Along the fault zone, there are several earthquake swarm areas, the northernmost of which are Schöneck and Werdau. In this study, we investigate the presumably fluid-induced earthquake swarm activity of the Schöneck and Werdau area. For this purpose, we apply two methods: local earthquake tomography and receiver functions to identify the structural composition of the crust, the areas affected by fluids and the origin of the fluids. We detected potential fluid paths characterised by high Vp/Vs ratios and granite intrusions nearby the swarms characterised by low Vp/Vs anomalies. Receiver function analysis yields the Moho at 25 to 33 km depth and two seismic discontinuities at 55 km and 68 km depth.
... The historical and instrumental seismicity occurring on some of these western structures (Gubbio 1984, Mw 5.6; Colfiorito 1997, Mw 6.0; Norcia 1979, Mw 5.9; and L'Aquila 2009, Mw 6.1) indicate that this sector of the chain is active. Conversely, the seismogenic behavior of the eastern fault system has been largely debated, mainly in the geological community [42][43][44][45]. The Mount Vettore and Gran Sasso faults can be considered silent in historical times [42]. ...
... The westernmost fault alignment extends from Gubbio to Colfiorito, Norcia, and L'Aquila. The eastern system develops from Mount Vettore to Amatrice Campotosto (Mount Gorzano fault) and Gran Sasso ridge ( [42][43][44], and references therein). The historical and instrumental seismicity occurring on some of these western structures (Gubbio 1984, M w 5.6; Colfiorito 1997, M w 6.0; Norcia 1979, M w 5.9; and L'Aquila 2009, M w 6.1) indicate that this sector of the chain is active. ...
... The historical and instrumental seismicity occurring on some of these western structures (Gubbio 1984, M w 5.6; Colfiorito 1997, M w 6.0; Norcia 1979, M w 5.9; and L'Aquila 2009, M w 6.1) indicate that this sector of the chain is active. Conversely, the seismogenic behavior of the eastern fault system has been largely debated, mainly in the geological community [42][43][44][45]. The Mount Vettore and Gran Sasso faults can be considered silent in historical times [42]. ...
We report composition, grain size, and rheological data related to the mud emitted as a consequence of the maximum moment magnitude (Mw max = 6.5) on 30 October 2016, commonly referred to as the Norcia earthquake (central Italy), and on the activity of pre-existent mud volcanoes affected by the central Italy seismic sequence started on 24 August 2016. The emission sites were located at Monteleone di Fermo and Santa Vittoria in Matenano, two municipalities near the town of Fermo (Marche Region, Italy). We sampled, measured, and analyzed the products of mud emissions 3 days after the mainshock to characterize the mud by geochemical, mineralogical, and rheological analyses. The muds’ geochemical composition and low electrical conductivity suggest a continental origin, likely belonging to the Colombacci Formation. The collected muds are silt–sand–water-rich suspensions characterized by a Bigham rheology with viscosity values between 6.3∙107 and 6.9∙105 Pa∙s. The calculated minimum fluidization velocity of the mud suspensions is between 0.05 m/s (grain size of 2 μm) and 0.74 m/s (grain size of 8 μm). Water-rich mud suspensions flowing on a slope move faster as the water content increases up to 30 wt.%. At higher values, the velocity remains almost constant due to the disaggregation of bonds among the solid particles in the mixtures.
... 2A) and caused over 300 casualties and the destruction of many settlements and towns (e.g., Galli et al., 2017). Before the 2016-2017 seismic sequence, many other Mw ≥ 6.0 extensional earthquakes had occurred in the central Apennines during histor- ical and pre-historical times, including the 1639 (MCS intensity 9.5-10) Amatrice earthquake, the 1915 Mw 6.7 Fucino earthquake, the 1997 Umbria Marche seismic sequence (maximum Mw 6.0), and the 2009 Mw 6.3 L'Aquila earthquake (e.g., Galadini and Galli, 2003;Boncio et al., 2004;Miller et al., 2004;Chiarabba et al., 2009;Cinti et al., 2021; Fig. 2A). ...
The central Apennines are a fold-thrust belt currently affected by post-orogenic ex- tensional seismicity. To constrain the influence that the inherited thrust-related structures exert on the present seismic behavior of the belt, we provide the high-resolution structural and hydraulic characterization of one of the most external exposed thrust fault systems of the central Apennines, the Sibillini Mts. Thrust Front (STF). We integrate structural mapping, multiscale structural analysis, and in situ air permeability on the brittle structural facies of the thrust zone. We also performed K-Ar dating of selected fault rocks to better constrain structural inheritance. The STF is defined by a complex, ∼300-m-thick deformation zone involving Meso-Cenozoic marl and limestone that results from the accommodation of both seis- mic and aseismic slip during shortening. Permeability measurements indicate that the low permeability (10^−2 ÷ 10^−3 D) of the marly rich host rock diminishes within the thrust zone, where the principal slip surfaces and associated S-C structures represent efficient hydraulic barriers (permeability down to ∼3 × 10^−10 D) to sub-vertical fluid flow. Field data and K-Ar dating indicate that the STF began its evolution ca. 7 Ma (early Messinian). We suggest that the studied thrust zone may represent a barrier for the upward migration of deep fluids at the hypocentral depth of present-day extensional earth- quakes. We also speculate on the influence that similar deformation zones may have at depth on the overall regional seismotectonic pattern by causing transient fluid overpressures and, possibly, triggering cyclic extensional earthquakes on normal faults prone to slip while crosscutting the earlier thrust zones (as per a classic fault valve behavior). This mechanism may have controlled the ori- gin of the 2016–2017 central Apennines devastating earthquakes.
... Laga based on geological evidence (Blumetti el al. 1993) and associated with an M max = 6.6, a striking angle of 150° and a steep dip. Boncio et al. (2004) linked the Mt. Laga system to the more detailed Mt. ...
... In some stretches, the fault scarp is visible and well exposed in the central part of the structure; it strikes N140-150° and dips 60-70° to the SW. Boncio et al. (2004) estimated an M max = 6.7 for this fault. The same magnitude was assumed by Pace et al. (2006) in designing the seismogenic boxes to compute seismic hazard. ...
... Therefore, we model a 28 km long and 13 km wide rupture area capable of generating an M W 6.7 (M 0 = 1.26×10 19 N*m) earthquake (Fig. 6). The fault strikes N150° and dips 65° to the SW (Fig. 6) in agreement with ITHACA (2019) and Boncio et al. (2004); the top of the rupture area is fixed at a depth of 1 km, while the simulated earthquakes nucleate at 11-12 km and propagate toward the surface. The slip distribution is a random field (Mai and Beroza 2002) stochastically consistent with slip distributions of past earthquakes. ...
We apply the Probabilistic Seismic Hazard Analysis (PSHA) and compute Physics-Based Simulations (PBS) of ground motion for three dams in the Campotosto area (Central Italy). The dams, which confine an artificial water reservoir feeding hydroelectric power plants, are located in an active seismic zone between the areas that experienced the 2009 L'Aquila and 2016-2017 Central Italy seismic sequences. The probabilistic disaggregation estimated for a return period of 2475 years, corresponding to the collapse limit state for critical facilities , indicates that the most dangerous fault is associated with a maximum magnitude of 6.75 ± 0.25 within a distance of 10 km. This fault is used in PBS to emulate the Maximum Credible Earthquake scenario. To capture the ground motion variability, we input a pseudo-dynamic source model to encompass spatial and temporal variations in the slip, rise time and rupture propagation, heavily affecting the near-source ground motion. Indeed, the ground motion above the rupture volume is mainly influenced by the epistemic uncertainties of rupture nucleation and slip distribution. The computed broadband seismograms are consistent with the near-source shaking recorded during the 2016 M W 6.6 Norcia earthquake and constrain the upper bound of the simulated ground motion at specific sites. Our modelling reinforces the importance of considering vertical ground motion near the source in seismic design. It could reach shaking values comparable to or larger than those of the horizontal components. This approach can be applied in other areas with high seismic hazard to evaluate the seismic safety of existing critical facilities.
... This magnitude-distance pair represents the most in uencing earthquake for the hazard estimate in the study area. The DSHA assumes as the worst possible case an Mw = 6.7 earthquake, consistently with some eld geology studies (e.g., Boncio et al., 2004) and provides the ground motion for three receivers at the three dams. ...
... Page 24/26 focal mechanism (Boncio et al., 2004) is plotted in the top right inset. We also show the capable active faults (red lines). ...
... The DISS database (DISS Working Group, 2018) reports the Campotosto fault as the composite normal seismogenic source of Col orito-Campotosto (M max =6.5); further, DISS (2018) and the ITHACA (2019) database report a debated seismogenic source of Mt. Laga based on geological evidence(Blumetti el al., 1993) and associated with an M max =6.6, a striking angle of 150° and a steep dip.Boncio et al. (2004) linked the Mt. Laga system to the more detailed Mt. ...
We apply the Probabilistic Seismic Hazard Analysis (PSHA) and Deterministic Seismic Hazard Analysis (DSHA) to estimate the input ground motion for three dams in the Campotosto area (Central Italy). The dams, which confine an artificial water reservoir feeding hydroelectric power plants, are located in an active seismic zone between the areas that experienced the 2009 L’Aquila and 2016–2017 Central Italy seismic sequences. The probabilistic disaggregation estimated for a return period of 2475 years, corresponding to the collapse limit state for critical facilities, indicates that the most dangerous fault is associated with a maximum magnitude of 6.75 ± 0.25 within a distance of 10 km. This fault is used in DSHA to emulate the worst-case scenario. To capture the ground motion variability, we input a pseudo-dynamic source model to encompass spatial and temporal variations in the slip, rise time and rupture propagation, heavily affecting the near-source ground motion. Indeed, the ground motion above the rupture volume is mainly influenced by the epistemic uncertainties of rupture nucleation and slip distribution. The computed broadband seismograms are consistent with the near-source shaking recorded during the 2016 MW 6.6 Norcia earthquake and constrain the upper bound of the simulated ground motion at specific sites. Our modelling reinforces the importance of considering vertical ground motion near the source in seismic design. It could reach shaking values comparable to or larger than those of the horizontal components.
This approach can be applied in other areas with high seismic hazard to evaluate the seismic safety of existing critical facilities.
... Vettore Fault System (MVFS) are among the most seismically active extensional fault systems in the central Apennines (Galadini and Galli, 2003;Galli et al., 2008;Falcucci et al., 2016;Buttinelli et al., 2021). After several earthquakes of small magnitude (Mw ≤4.0) and diffuse microseismicity that occurred in the hanging wall of the MGF (Boncio et al., 2004a;Bigi et al., 2013), the MFG and MVFS generated the 2016-2017 Amatrice-Norcia sequence, which included the Mw 6.0 Amatrice and Mw 6.5 ...
... Galli et al., 2017). The Mw 6.0 Amatrice earthquake nucleated along the MGF at a depth of ~7 km and represents the last record of MGF tectonic activity (Lavecchia et al., 2016;Chiaraluce et al., 2017), which includes also the 2009 Mw 6.3 L'Aquila earthquake (Chiarabba et al., 2009), the historical 1639 Amatrice earthquake (Boncio et al., 2004a) and pre-historical events in the last ~8 ky revealed by paleoseismological analyses (Galadini and Galli, 1999;Galli, 2003, Galli et al., 2008). The early tectonic evolution of the MGF, however, is substantially unknown and its onset was dated to be in the Pliocene by basin-filling continental deposits (Cacciuni et al., 1995;Cavinato and Celles, 1999;Boncio et al., 2004a). ...
... The Mw 6.0 Amatrice earthquake nucleated along the MGF at a depth of ~7 km and represents the last record of MGF tectonic activity (Lavecchia et al., 2016;Chiaraluce et al., 2017), which includes also the 2009 Mw 6.3 L'Aquila earthquake (Chiarabba et al., 2009), the historical 1639 Amatrice earthquake (Boncio et al., 2004a) and pre-historical events in the last ~8 ky revealed by paleoseismological analyses (Galadini and Galli, 1999;Galli, 2003, Galli et al., 2008). The early tectonic evolution of the MGF, however, is substantially unknown and its onset was dated to be in the Pliocene by basin-filling continental deposits (Cacciuni et al., 1995;Cavinato and Celles, 1999;Boncio et al., 2004a). ...
The Mt. Gorzano Fault (MGF) is a major seismically active extensional fault of the central Apennines, responsible for the destructive Mw 6.0 Amatrice earthquake in 2016. The MGF developed during post-orogenic extensional tectonics, generating a continental basin in the hanging wall. The age of the onset of the MGF and the relationship among faulting, fluid circulation, and the seismic cycles are unknown. We investigate these issues by studying the footwall damage zone of the MGF (exhumed from ~2-3 km depth), where extensional structures and related mineralizations cut and partially overprint the pre-existing compressional orogenic fabric. Structural and geochemical analyses (REE, O, C and clumped isotopes) combined with U-Pb dating of calcite mineralizations show that extensional deformation along the MGF began at least ~2.5 Myr ago. Its activity has continued to the present-day with a mean slip rate of ~0.9 mm/yr, consistent with other seismically active extensional faults of the central Apennines. During Apennine contractional tectonics, orogenic structures and tectonic overburden hindered the ascent of deep fluids, which, therefore, may have been progressively overpressured. We postulate that such overpressure occasionally or cyclically triggered impulsive deformation (earthquakes). During the subsequent extensional phase (younger ~2.5 Ma), pre- or co-seismic crustal dilation opened pathways for the ascent of deep mineralizing fluids, which impregnated the fault damage zone and may have triggered earthquakes. The crustal reservoir of carbonate-rich fluids nowadays is the source of water for the Acquasanta thermal springs close to the Mt. Gorzano seismic area.
... The activated main fault is mostly normal in this region where the extension is attuned by a complex set of NW-SE and NNW-SSE striking, mostly SW dipping normal fault systems. The geologic slip rates are ranging between 0.5 and 1.3 mm/year [30,31], while the total rate of extension is varying between 1.0 and 3.0 mm/year based on the geodetic observations [32,33]. ...
During the 2016–2017 Central Italy earthquake sequence, a series of moderate to large earthquakes M > 5 occurred near the Amatrice and Norcia towns. These events are recorded on a dense seismic network, providing relevant observational evidence of complex earthquakes in time and space. In this work, we used this substantial data set to study the ground-motion characteristics of the Norcia earthquake M6.5 on October 30, 2016, through a broadband ground-motion simulation. Three-component broadband seismograms are generated to cover the entire frequency band of engineering interest. Low and high frequencies are computed considering the heterogeneous slip rupture model of Scognamiglio et al. (2018) [1]. High frequencies are calculated using a stochastic approach including P, SV, and SH waves, while low frequencies are obtained through a forward simulation of the kinematic model at the various stations. To predict earthquake-induced ground-motions in the area, we adopted region-specific attenuation and source scaling parameters derived by Malagnini et al. (2011) [2]. Ground-motion parameters, including peak ground acceleration (PGA), peak ground velocity (PGV) and spectral amplitudes, are calculated at the selected sites adopting physics-based parameters to understand better the earthquake fault rupture, the wave propagation, and their impacts on the seismic hazard assessment in the region. We showed that combining the fault rupture history over the entire frequency spectrum of engineering interest, the attenuation characteristics of the seismic wave propagation and the properly defined site responses can improve the prediction of ground-motions and time histories, especially in near seismic sources.
... The central Apennines, one of the most seismically active regions in Italy (Akinci et al. 2009), is formed in the Miocene to Pliocene under the ongoing subduction environment where the Adriatic Plate collides with and plunges beneath the Eurasian Plate (Liu et al. 2017). Previous geodetic studies (Boncio et al. 2004, Galli et al. 2008, Pizzi and Galadini 2009) have identified that several NW-SE trending normal fault systems are activated in this area. On 24th August, 2016, an Mw 6.3 earthquake struck central Italy, with the epicenter near towns of the Norcia and Amatrice. ...
Numerous shallow earthquakes, including 24th August Amatrice, 26th October Visso, and 30th October Norcia earthquakes, ruptured the segments of Mount Vettore-Gorzano fault system in the central Apennines (Italy) in 2016. In order to investigate the stress perturbation and triggering patterns among the earthquake sequences, we introduce a more realistic nonplanar coseismic fault geometry model, which improve the rupture model by assimilating relocated aftershocks and the GPS observations. We adopt the seismic slip inversion program of the steepest descent method (SDM) to create the detailed coseismic rupture models and optimize Coulomb Failure Stress model by varying the coefficient of friction and received fault parameters. The results indicate that the nonplanar fault geometry model is more reflective of the deep slip of the coseismic rupture than planar model. As evidenced by the coseismic Coulomb stress changes caused by the three mainshocks at different depth slices, the stress loading mainly distributes on the active fault zones and the stress changes can well explain the spatial distribution of aftershocks. The first large Amatrice mainshock accelerates the occurrence of the Mw 5.9 Visso and Mw 6.6 Norcia earthquakes, with the positive stress changes at the hypocenter exceeding the stress triggering threshold (0.010×106 Pa) and up to 0.015×106 and 0.257×106 Pa, respectively. Furthermore, the Mw 5.9 Visso earthquake as well encourages the occurrence of the Mw 6.6 Norcia event with the increased stress changes of 0.052×106 Pa on the hypocenter. It is concluded that the stress transfer and accumulation play crucial roles on the linkage triggering mechanism among the mainshock-mainshock and mainshock-aftershocks. Noteworthily, the cumulative stress changes on the southwest segment of the Norcia Fault (NF), the southeast parts of the Montereale Fault System (MFS) and Mount Gorzano Fault (MGF) of the main regions are up to (1.5∼3.5) ×106 Pa. The cumulative stress changes have not been released sufficiently by aftershocks, which may increase the seismic hazard in those regions.
