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Oblique view of three-dimensional model of imbricate thrust structures in the Longmen Shan (China) fold-and-thrust belt and Sichuan Basin. Red lines are surface ruptures in the Wenchuan earthquake on the Beichuan and Pengguan faults. Green points are aftershocks of the Wenchuan earthquake. Red and yellow hypocenters are aftershocks of the Lushan earthquake (Fang et al., 2013). Blue spheres are hypocenters that were recorded from 1992 to 2002 (Zhu et al., 2005). QTF-Qiongxi thrust fault.
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Thrust and reverse faults pose significant earthquake hazards in convergent plate margins around the world, but have proven difficult to study given the complex nature of their ruptures, which often involve multiple along-strike and vertically stacked fault segments. The 2013 Mw 6.6 Lushan earthquake exemplified this complexity, rupturing a blind t...
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Citations
... Subsequently, the 1568 M 6¾ Xi'an northeast earthquake was confirmed to occur along the JWF near the northwest of the WTF (Ma et al., 2019). Similar cases have taken place in historical earthquakes, such as the 1982 New Idria-1983Coalinga-1985 Kettleman Hills earthquake sequence in California, the 2008 M 7.9 Wenchuan-2013 M 7.0 Lushan earthquake sequence in China (Yeats et al., 1997;Wang et al., 2014), and the 2023 M 7.8 and 7.6 earthquake doublet in Türkiye. ...
Active faults that develop in urban regions pose significant seismic hazards to cities with densely concentrated populations and wealth, as demonstrated by several destructive earthquake events in the recent decades. Lintong–Chang’an fault is a known active fault, which comprises multiple branches and traverses the urban area of Xi’an in Weihe Graben—a prominent Chinese megacity with a rich 3000-year-old civilization and a population of 13 million. High-resolution seismic reflection profiles and borehole transects, combined with Quaternary strata dating, reveal that: (1) to the south of Shenhe Loess Tableland, two northern branches of the fault zone follow the trend of the middle part and extend to the front of the Qinling mountains in the SW240° direction; (2) the strata since the late Middle Pleistocene on the borehole transect have been offset, with the vertical displacement of the ∼216 ka layer measured at 5.9 ± 0.3 m, the ∼118 ka layer at 3.8 ± 0.3 m, and 41 ka layer at 1.0 ± 0.1 m, indicating an average vertical slip rate of 0.02–0.04 mm/yr for the individual branch at the study site. Notably, the slip rate of the entire fault zone could be two to three times that of a single branch. Despite the relatively low-slip rate, the fault traverses the megacity of Xi’an, is situated in the relay zone of two large, strongly active basin boundary normal faults (Huashan and Qinling Piedmont faults) and is responsible for the formation of Xi’an ground fissures. Hence, it is necessary to pay special attention to this fault.
... Correspondingly, the electrical resistivity near the surface in the Songpan-Ganzi block is higher than in the Sichuan Basin. Seismic investigations [45] have revealed that, from the near surface to a depth of approximately 10 km, Paleozoic strata have developed. Near the southeastern side of the first Lushan earthquake epicenter, a syncline has formed, with its western side corresponding to the Songpan-Ganzi block and its eastern side corresponding to the Sichuan Basin. ...
On 1 June 2022, a magnitude 6.1 earthquake struck the southern segment of the Longmenshan fault zone on the eastern edge of the Tibetan Plateau, once again causing casualties and economic losses. Understanding the deep-seated dynamic mechanisms that lead to seismic events in the Lushan earthquake area and assessing the potential hazards in seismic gap areas are of significant importance. In this study, we utilized 118 magnetotelluric datasets collected from the Lushan earthquake area and employed three-dimensional electromagnetic inversion with topographic considerations to characterize the deep-seated three-dimensional resistivity structure of the Lushan earthquake area. The results reveal that the Shuangshi–Dachuan fault in the Lushan earthquake area can be divided into two relatively low-resistivity zones: a western zone dipping southeastward and an eastern zone with a steeper slightly northwestern dip. These two zones intersect at a depth of approximately 20 km, forming an extensional pattern resembling a “Y” shape. The epicenters of both the 2013 and 2022 Lushan earthquakes are primarily located in the upper constricted portion of the pocket-like low-resistivity body at depth. The distribution of seismic aftershocks is confined within the region enclosed by the high-resistivity body, following the pattern of the Y-shaped low-resistivity zone.
... However, research findings also indicate that the impact of natural disasters on oil returns is nuanced. While natural disasters can cause short-term volatility in oil prices, their long-term effects might be less significant, with other factors such as geopolitical tensions and economic growth having a more prominent influence [63,64]. The relationship between natural disasters and oil returns becomes particularly relevant in the context of climate change. ...
... The result is presented in Table 12 below. This finding is consistent with previous studies that have demonstrated the influence of natural disasters on the financial market [43,58,63]. Figure 5 from our analysis depicts spillovers received from NDI and GRI variables, proving that the spillover increase in 2020 was caused specifically by the COVID-19 pandemic via increasing the NDI and in 2022 by Russian special military operations via the GPR index. ...
This research utilizes the Diebold and Yilmaz spillover model to examine the correlation between geopolitical events, natural disasters, and oil stock returns in Asian OPEC+ member countries. The study extends prior research by investigating the dynamics of the Asian OPEC+ oil market in light of recent exogenous events. The analysis commences by creating a self-generated Asian OPEC+ index, which demonstrates significant volatility, as indicated by GARCH (1, 1) model estimation. The results obtained from the Diebold and Yilmaz spillover test indicate that, on average, there is a moderate degree of connectedness among the variables. However, in the event of global-level shocks or shocks specifically affecting Asian OPEC+ countries, a heightened level of connectedness is found. Prominent instances of spillover events observed in the volatility analysis conducted during the previous decade include the COVID-19 pandemic, the conflict between Russia and Ukraine, and the Turkey earthquake of 2023. Based on the facts, it is recommended that investors take into account the potential risks linked to regions that are susceptible to natural calamities and geopolitical occurrences while devising their portfolios for oil stocks. The results further highlight the significance of integrating these aspects into investors’ decision-making procedures and stress the need for risk management tactics that consider geopolitical risks and natural disasters in the oil equity market.
... The rapid and sustained development of such a magnificent intra-continental collision zone, amidst such a complex tectonic paradox, remains a subject of intense debate and scrutiny, but remains elusive to date. To address this problem, a series of main models have been proposed, including ductile lower crustal flow model (Burchfiel, 2004;Clark et al., 2005) and brittle upper crustal thrusting (Royden et al., 1997;Tapponnier et al., 2001;Royden et al., 2008;Hubbard and Shaw, 2009;Hubbard et al., 2010;Li et al., 2010;Wang et al., 2011;Wang et al., 2014). ...
... The Cenozoic thrusting formed three anticline belts, namely Huangnigang-Gaojiachang anticline (HGA), Xiongpo anticline and Longquan anticline, and two gentle synclines in foreland of the SWSB (Figure 1). The SWSB consists of a two-level detachment system: a gently dipping Pre-Sinian basal detachment at a depth of 15-18 km and a upper hinterland-dipping Mid-Triassic detachment located in the basin interior at a depth of 5-7 km ( Figure 2) (Hubbard and Shaw, 2009;Hubbard et al., 2010;Jia et al., 2010;Wang et al., 2014). The RFBF links these detachments, forming a flat-ramp-flat structure and making hanging wall a fault blend fold Wang et al., 2022). ...
Introduction: The southwestern Sichuan fold-thrust belt (SWSB) is a duplex detachment system and features the basal Precambrian detachment at a depth of approximately 15–17 km and the upper Mid-Triassic detachment. Moreover, the SWSB undergoes forward-breaking propagation during the Cenozoic. To date, the mechanism and kinematic evolution governing the SWSB in this thrusting deformation as well as the way the two detachments control the structural deformation pattern of the SWSB remains unknown.
Methods: In this work, three discrete-element numerical models with the same strong upper detachment but basal detachments with different mechanical strengths and thicknesses were designed to study the deformation of the SWSB.
Results: The results indicate that for the Model I with a strong frictional basal detachment with thickness of 500 m, most deformation and thrust faults concentrate near the mobile backwall. Model I exhibits characteristics such as linearly increasing wedge height and stepwise increasing wedge width and slope angle. For the Model II with a modest frictional basal detachment with thickness of 500 m, the strain and deformation propagate into the foreland quickly and multiple back-thrust and thrust faults form on the upper detachment in the second thrusting period. The first thrusting period in Model II, exhibits similarities with Model I. However, in the second period, the wedge reaches a stable state, and its geometry remains constant. In this stage, the deformation propagates along the shallow detachment into the right side of the model. The geometry and activity of thrust faults in the foreland differ significantly in the model III with a modest frictional basal detachment but a greater thickness. Two additional pop-up structures are generated in the second period in this model. The first half of the first thrusting period is similar to the first two models. In the second half of the first period and the second period, the wedge is in a stable state. In the first stage of the shortening, all models undergo a transition from a subcritical state to entering a supercritical state, which indicates that the deformation is progressing rapidly along the basal detachment towards the right side of the model.
Discussion: The results of Model III are consistent with the deformation pattern of the SWSB. The study of the kinematics and interaction between two detachments could help hydrocarbon exploration beneath the upper detachment.
... The two earthquakes caused great losses of human lives and properties in China. Many researchers focus on the mechanism of two earthquakes because they occurred at a close distance with distinct fault geometry, surface rupture, coulomb stress, and deep structure Li et al., 2013Li et al., , 2014Lei and Zhao, 2010;Pei et al., 2010;Shan et al., 2013;Wang et al., 2009Wang et al., , 2014aWang et al., , 2015Wang et al., , 2017aWu et al., 2013;Zhan et al., 2013; ...
Although many geophysical models have been proposed in the Longmenshan fault zone (LFZ) and its surrounding areas, the deep structure of the seismic gap and its constraint of the Wenchuan and Lushan earthquakes remain uncertain. Based on the compiled aeromagnetic data and Bouguer gravity data, we have tried to create a more detailed and visible magnetic and density model beneath the LFZ using 2D forward modeling and 3D inversion. The research shows that structure heterogeneities are widely distributed beneath the LFZ. The earthquake epicenters show high magnetic anomalies and the edge of high Bouguer gravity anomalies that consist of rigid blocks where apt to accumulate stress. However, the seismic gap shows low magnetic anomalies and transition of Bouguer gravity anomalies related to a weak zone. The Sichuan Basin has two NE-trending banded high magnetic blocks extending beneath the LFZ that firmly support the crust of the Sichuan Basin was downward subduction toward the LFZ. More importantly, the basement subducts to approximately 33 km west of the Wenchuan-Maoxian fault with a low dip angle beneath the middle segment of the LFZ, whereas the distance decreases to approximately 17 and 19 km under the southern segment. Thus, the crust of the Sichuan Basin beneath the middle segment extends farther than that beneath the southern segment with the seismic gap as the transition zone. Therefore, we propose that the structural heterogeneity of the basement on the western margin of the Sichuan Basin may be the main reason for the different focal mechanisms and geodynamics of the Wenchuan and Lushan earthquakes.
... There are several local multiscale velocity anomalies in the eastern and western branches of the HYS fault belt, which may be the result of regional tectonic processes inferred from surface geological structural characteristics. The 3.0-km·s -1 isodepth is distributed at depths of 5.0-7.0 km, which is coincident with the previously-reported depth of the detachment layer in the Sichuan Basin (Hubbard and Shaw, 2009;Jia D et al., 2010;Wang MM et al., 2014;Zhang M et al., 2019), and the earthquake sequences are mainly located above the detachment layer (Yi GX et al., 2020, 2021. The variations in isodepth may imply that the buried depth of basement deposits is shallower in the YJS syncline, indicating the features of a stable sedimentary basin. ...
On 16 September 2021, a Ms 6.0 earthquake struck Luxian Country, one of the shale gas blocks in Southeastern Sichuan Basin, China. To reveal the seismogenic environment and its mechanism, we invert a fine three-dimensional S-wave velocity model from ambient noise tomography using data from a newly deployed dense seismic array in the source area, by extracting and jointly inverting the Rayleigh phase and group velocities in the period of 1.6 ~7.2 s. The results show that the velocity model varies significantly beneath different geological units. The Yujiasi syncline is characterized by low velocity within a depth of about 3.0 ~ 4.0 km, corresponding to the stable sedimentary layer in Sichuan basin. The eastern and western branches of the Huayingshan fault belt generally show high velocity in the NE-SW direction, except for several local low-velocity anomaly zones. The Luxian Ms 6.0 earthquake is located at the boundary between the high- and low-velocity zone, and the earthquake sequences expand eastward from the source area with a depth of 3.0 ~ 5.0 km. Integrated with the velocity variations around the source area, the distribution of aftershock sequences, and the focal mechanism solution, it is speculated that the seismogenic mechanism of the main shock might be interpreted as the reactivation of pre-existing or tear faults caused by hydraulic fracturing.
... The epicenter of this earthquake was located in the foreland of the southern Longmen Shan where the Coulomb stress increased due to the Wenchuan earthquake. It was a typical blind thrust earthquake [3]. The biggest feature of the southern segment of Longmen Shan compared with the central and northern segments is that the faults are scattered and extend to the interior of the Sichuan basin. ...
... sent-day convergence rates across the northwestern margin of the Tibetan Plateau (from 75° to 80°E) range from 15 to 10 mm/yr (M. Wang et al., 2020). The devastating 2008 Wenchuan Mw 7.9 earthquake and the subsequent 2013 Lushan Mw 6.6 earthquake demonstrated ongoing crustal shortening in the Longmen Shan fold-and-thrust belt Liu-Zeng et al., 2009;M. Wang et al., 2014;Xu et al., 2009). These recent catastrophic earthquake events require us to reconsider the processes between crustal shortening, rapid uplift, syn-tectonic sedimentation, and erosion of Longmen Shan and Sichuan Basin in the eastern margin of the Tibetan Plateau, and their influences on fault activity and seismic hazards. ...
... BT), the Pengguan Thrust (PGT), and the Range Front Blind Thrust (RFBT) (Figures 1 and 5). The Longmen Shan consists of a two-level detachment system: a gently dipping basal detachment at a depth of 15-18 km and a shallow detachment located in the basin interior at a depth of 5-7 km, dipping toward the hinterland (Figures 5 and 6) Jia et al., 2010;M. Wang et al., 2014). Basement-involved thrust-related structures have developed in the hinterland region of the Longmen Shan. In the WSFB, an array of northeast-and north-northeast-striking thrust-related folds are formed above the Triassic evaporitic sequence detachment, which is consistent with the thin-skinned tectonic model. Based on balanced cross-sec ...
We investigated interactions between structural deformation and surface processes in the Longmen Shan fold‐and‐thrust belt and the adjacent western Sichuan foreland basin (WSFB) in the eastern margin of the Tibetan Plateau. The discrete‐element modeling (DEM) method was used to study the influences of the various mechanical properties of the detachments and syn‐tectonic erosion/deposition on the structural evolution of the Longmen Shan and WSFB. DEM simulations demonstrated two stages of surface processes during the Late Cenozoic profoundly influenced thrusting sequences and strain localization in the hinterland and foreland portions of the Longmen Shan. Models indicate that the fold‐and‐thrust belt lacking surface processes propagate in a forward‐breaking manner, whereas those with surface processes develop following an out‐of‐sequence thrusting pattern. We infer that large‐scale erosion propagation from the Sichuan Basin westward to the Tibetan Plateau since Late Cenozoic caused the Longmen Shan hinterland to reach a subcritical wedge state. Tectonic activity retreats to the edge of Plateau, enhancing the rapid uplift of the Longmen Shan and inhibiting the propagation of substantial shortening deformation to the foreland basin. The foreland thrust belt slides stably along the shallow detachment, causing the initiation and growth of the Longquan fault in the leading front. These results explain why both the Longmen Shan hinterland and the western Sichuan foreland thrust belts are currently in a state of simultaneous seismic activity. Our findings offer important implications regarding the seismic potentials of other fold‐and‐thrust belts that interact with dynamic surface processes.
... Topographic and structural cross sections across three typical mountain front with recent earthquakes (a): the 2013 M w 6.6 Lushan earthquake in the front of southern Longmen Shan (eastern margin of the Tibetan Plateau). Structural cross section is modified from Hubbard et al. (2010) and Wang et al. (2014). An inherited Paleozoic normal fault that may have participated in the Lushan earthquake is also indicated (Lu et al., 2017a, black dash lines). ...
... However, due to a lack of surface ruptures and the limited depth extent (0-10 km depth) of the existing seismic profiles, the seismogenic structure near the hypocenter of the Lushan earthquake at a depth of ≥10 km still remains unclear. Based on the folding of shallow strata on seismic reflection profiles, a gently dipping (25 • -35 • ) wedge front, blind ramp extending through the hypocenter of the Lushan earthquake has been identified (e.g., Hubbard et al., 2010;Li Y. et al., 2014;Wang M. et al., 2014;Li Z. et al., 2017, f1 in Fig. 15c). The associated growth strata reveal Quaternary activity for this fault (Li Z. et al., , 2017Wang M. et al., 2013aWang M. et al., , 2013bWang M. et al., , 2014, and it is generally accepted that part of this ramp has been ruptured in the Lushan earthquake. ...
... Based on the folding of shallow strata on seismic reflection profiles, a gently dipping (25 • -35 • ) wedge front, blind ramp extending through the hypocenter of the Lushan earthquake has been identified (e.g., Hubbard et al., 2010;Li Y. et al., 2014;Wang M. et al., 2014;Li Z. et al., 2017, f1 in Fig. 15c). The associated growth strata reveal Quaternary activity for this fault (Li Z. et al., , 2017Wang M. et al., 2013aWang M. et al., , 2013bWang M. et al., , 2014, and it is generally accepted that part of this ramp has been ruptured in the Lushan earthquake. However, this gentle wedge front ramp does not match well with the focal mechanism solutions, distribution of aftershocks and coseismic slip modes inferred from GPS, InSAR, and strong motion data that suggest a steeper-dipping coseismic fault for the Lushan event (39 • from Du et al., 2013;42.1 • in Huang et al., 2019;43 • in Jiang et al., 2014;or up to 45 • -50 • in Li et al., 2013, Han et al., 2014and Fang et al., 2015. ...
Earthquakes reported in the frontal belts of active orogenic wedges such as the 2013 Mw6.6 Lushan and 1999 Mw7.6 Chi-Chi earthquakes, highlight the importance of
loading exerted by mountainous topography and inherited fault zones. However, their effects on formation and activation of these wedge front fault systems remain
poorly understood. This study presents three sets of sandbox experiments in which topographic loading and geometry of inherited faults were first separately
investigated, then explored jointly. Experiments show that smaller topographic loading favors gentle-dipping wedge front thrusts, while larger topographic loading
promotes the development of steep wedge front faults. Introduced as zones of frictional weakness, all inherited faults promote deformation localization, though the
steep ones are characterized by buttressing nearby rather than direct slip on themselves. When the two factors were tested integrally, four major deformation modes
arose, including (1) direct reactivation; (2) fault truncation in the initial stage of compression; (3) stacking of small thrusts against the inherited fault and possible
truncation in a later evolutionary stage; (4) behavior as a fossil structure. These modes show differences not only in first-order deformation styles, but also in the
distribution of secondary structures, defining a basic framework and providing new guides for the interpretation of complex wedge front fault systems and their
activities, in areas such as the Longmen Shan (eastern Tibet), the Tian Shan and the western margin of the Taiwan orogen.
... This may indicate continuous activity in the foreland region. According to seismic profiles (Figure 9(b)), previous studies have proposed that two imbricated, blind thrust faults are developed beneath the front range of the Longmen Shan [35,36,40], which has extended into the Sichuan Basin and would affect the densely populated area in the basin (Figure 9(b)). In this study, we also found that the anticlines, which are generated by the upper blind thrust fault, were active during the Late Quaternary (Figure 9(b)). ...
... (b) Geological cross-section showing the setting of Mesozoic and Cenozoic strata in the foreland basin (S-S′, position shown in Figure 2). (c) Seismic section of the foreland basin (A-A′ and B-B′, locations shown in Figure 1), in which the interpretation of the A-A′ and B-B′ sections follows the studies of Li et al. and Wang et al.[16,36,40]. (d) Deep structures of the southern Longmen Shan and its foreland basin[5]. ...
As the eastern boundary of the Tibetan Plateau, Longmen Shan possesses a narrow thrust belt with steep topography but lacks matching Cenozoic foreland basin. Multiple kinetic models have been proposed to debate on the dominant mechanism of developing such range–foreland system. Crustal shortening rate is a feasible approach to test different tectonic models and estimate structural patterns. In this study, we focused on the deformation pattern and shortening rate of the complex foreland area of the southern Longmen Shan, which is comprised of the Xiongpo, Sansuchang, and Longquanshan anticlines. By the means of net-based RTK measurement and Quaternary chronology, we measured and dated the six-level terraces of the Qingyi River, which flows southeastward across this region. Excess area method was applied to calculate shortening rate. The results indicate that the Late Quaternary shortening rates of the Xiongpo anticline, Longquanshan anticline, and Sansuchang anticline are 1.01 mm/yr, 0.89 mm/yr, and 0.16 mm/yr, respectively. The total shortening rate of the foreland in southern Longmen Shan is 2.06 mm/yr. Consequently, a mechanical model was presented to show the tectonic pattern: the southern Longmen Shan is an actively expanding edge of the plateau, and the shortening is distributed to the three anticlines dominated by the foreland detachment system. This model supports that crustal shortening is the dominating force in the current orogenesis of the Longmen Shan. In addition, the along-strike variation of the Longmen Shan was further specified from the perspective of crustal shortening distribution. We propose that the southern Longmen Shan and its foreland basin are in a state of compression, while the northern Longmen Shan has both thrust and strike-slip characteristics.
