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Geodetic constraints on the September 2022 Guanshan and Chihshang earthquakes, eastern Taiwan 2022年9月台湾东部关山和池上地震的大地测量约束
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230600
Hsin Tung , Horng-Yue Chen , Ya-Ju Hsu , Chi-Hsien Tang , Jian-Cheng Lee , Yu Wang , Hung Kyu Lee
{"title":"Geodetic constraints on the September 2022 Guanshan and Chihshang earthquakes, eastern Taiwan","authors":"Hsin Tung ,&nbsp;Horng-Yue Chen ,&nbsp;Ya-Ju Hsu ,&nbsp;Chi-Hsien Tang ,&nbsp;Jian-Cheng Lee ,&nbsp;Yu Wang ,&nbsp;Hung Kyu Lee","doi":"10.1016/j.tecto.2024.230600","DOIUrl":"10.1016/j.tecto.2024.230600","url":null,"abstract":"<div><div>We characterize the spatiotemporal patterns of ground deformation caused by an earthquake doublet: the September 17, 2022, M<sub>L</sub> 6.6 Guanshan and the September 18, 2022, M<sub>L</sub> 6.8 Chihshang earthquakes occurred on the Central Range fault, eastern Taiwan. We use geodetic data collected from continuous and campaign-mode GNSS stations, as well as two precise leveling routes to estimate coseismic displacements and invert for fault slip distributions. The M<sub>L</sub> 6.6 foreshock caused northwestward horizontal displacements and uplift reaching 200 mm and 170 mm, respectively, in the region between Chihshang and Taitung. Seventeen hours later, the M<sub>L</sub> 6.8 mainshock generated coseismic displacements about four times larger than the foreshock, with horizontal displacements exceeding 900 mm and vertical displacements of 800 mm in the area between Guanshan and Ruisui. The maximum horizontal and vertical coseismic displacements of the entire earthquake sequence exceed one meter. The epoch-by-epoch high-rate GNSS data reveal significant seismic shaking, with maximum displacement exceeding 600 mm and 1100 mm during the foreshock and mainshock ruptures, respectively, correlating with severe infrastructure damage near surface ruptures. The dense spatial coverage of networks allows us to map the largest surface deformation along the Yuli fault, a branch of the steeply west-dipping Central Range fault, as well as the associated pop-ups along the east-dipping Longitudinal Valley fault. This observation suggests a likely coseismic and/or postseismic slip along the Longitudinal Valley fault. Our slip model indicates a maximum slip of approximately 3 m at a depth of 4.5 km to the west of Yuli, primarily on the Central Range fault. The coseismic slip extends over 50 km along the fault with two asperities near the hypocenter and Yuli. In addition, the Longitudinal Valley fault is characterized by shallow slip, with a maximum of 0.85 m at depths of 0–3 km.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230600"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Are strain rate lows proxies of low-potential of strong earthquakes? A case study in Western China 低应变率是强地震低势能的代用指标吗?中国西部案例研究
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230576
Yanqiang Wu , Changyun Chen , Zaisen Jiang , Jingwei Li , Mikhail Vladimir Rodkin , Valeri Grigorevich Gitis , Yajin Pang , Yuan Li
{"title":"Are strain rate lows proxies of low-potential of strong earthquakes? A case study in Western China","authors":"Yanqiang Wu ,&nbsp;Changyun Chen ,&nbsp;Zaisen Jiang ,&nbsp;Jingwei Li ,&nbsp;Mikhail Vladimir Rodkin ,&nbsp;Valeri Grigorevich Gitis ,&nbsp;Yajin Pang ,&nbsp;Yuan Li","doi":"10.1016/j.tecto.2024.230576","DOIUrl":"10.1016/j.tecto.2024.230576","url":null,"abstract":"<div><div>Strain accumulation is closely related to the occurrence of strong earthquakes. To investigate the pre-seismic deformation status of strong earthquakes, the correlation between the GNSS (Global Navigation Satellite System) strain rates and earthquakes subsequent to the GNSS observation period in Western China was studied. The primary results show that a large part of <em>M</em><sub>W</sub> ≥ 6.0 earthquakes occurred in the medium and low value regions (MLVR) of the second invariant of strain rate (SR). Meanwhile, about 81 % of strike-slip earthquakes occurred in the MLVR of the maximum shear strain rate, and the ratios are 72 % and 100.0 % for the reverse-faulting and normal-faulting earthquakes in the MLVR of principal compressive and tensile strain rates, respectively. The sustained slow fault slip rates, complex faults in different stages of inter-seismic period, and historical earthquakes, may possibly cause the typical strain rate patterns for the pre-seismic stage. Therefore, <em>M</em>w ≥ 6.0 earthquakes possibly occur in MLVR of strain rates, and low strain rate is not an indicative of low-potential of strong earthquakes.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230576"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Modeling the rupture dynamics of strong ground motion (> 1 g) in fault stepovers 断层阶跃中强地面运动(> 1 g)的破裂动力学建模
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230580
Julian Lozos , Sinan Akçiz , Holland Ladage
{"title":"Modeling the rupture dynamics of strong ground motion (> 1 g) in fault stepovers","authors":"Julian Lozos ,&nbsp;Sinan Akçiz ,&nbsp;Holland Ladage","doi":"10.1016/j.tecto.2024.230580","DOIUrl":"10.1016/j.tecto.2024.230580","url":null,"abstract":"<div><div>Following the July 2019 Ridgecrest, California earthquakes, multiple field investigators noted that pebble- to boulder-sized rocks had been displaced from their position in the desert pavement within a stepover along the right-lateral strike-slip M7.1 rupture trace, without evidence of dragging or shearing. This implies localized ground motions in excess of 1 g, in contrast to the instrumentally recorded peak of 0.57 g. Similar rock displacement occurred in a stepover in the predominantly strike-slip 2010 M7.2 El Mayor-Cucapah earthquake. Together, these examples suggest that some aspect of how earthquake rupture negotiates a strike-slip fault stepover produces extremely localized strong ground acceleration. Here, we use the 3D finite element method to investigate how rupture through a variety of strike-slip stepover geometries influences strong ground acceleration. For subshear ruptures, we find that the presence of a stepover in general matters more than its dimensions; the strongest ground acceleration always occurs at the end of the first fault. For supershear ruptures, the stepover is effectively irrelevant, since the strongest particle acceleration occurs at the point of the supershear transition on the first fault. Our model subshear and supershear ruptures alike do produce horizontal particle acceleration above 1 g, but over a region so close to the fault (&lt; 1 km) that a seismic network may not catch it. We suggest that the physics of rupture through a fault stepover could have been responsible for the displaced rocks in the Ridgecrest and El Mayor-Cucapah earthquakes, and that stepover regions may have particularly high ground motion hazard. Our study suggests that ground motion predictions and local hazard assessments should account for much stronger accelerations in the immediate near field of active faults, especially around stepovers and other geometrical discontinuities.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230580"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Applying and validating Coulomb rate-and-state seismicity models in acoustic emission experiments 库仑率态地震活动性模型在声发射实验中的应用与验证
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230574
Elías Rafn Heimisson , Milad Naderloo , Debanjan Chandra , Auke Barnhoorn
{"title":"Applying and validating Coulomb rate-and-state seismicity models in acoustic emission experiments","authors":"Elías Rafn Heimisson ,&nbsp;Milad Naderloo ,&nbsp;Debanjan Chandra ,&nbsp;Auke Barnhoorn","doi":"10.1016/j.tecto.2024.230574","DOIUrl":"10.1016/j.tecto.2024.230574","url":null,"abstract":"<div><div>A central goal of laboratory seismology is to infer large-scale seismic processes from small-scale experiments, with acoustic emissions (AE) being a common observable. These signals, indicative of microfracturing, slip localization, and damage evolution, are often paralleled with earthquakes to understand seismic behaviors. This study challenges traditional perspectives by applying Coulomb rate-and-state seismicity theory, originally developed for earthquake clustering, to AE experiments. This theory maps stressing history to seismicity rates using rate-and-state friction, however, its validity under controlled experimental conditions remains an open question. We conducted four experiments on a sawcut sample of red felser sandstone, representing a fault under variable stress conditions. Adjustments in loading rates and initial conditions revealed that, while a single free parameter <span><math><mi>A</mi></math></span>—related to the direct effect—should suffice, a rescaling of the model by 1.5 to 2.2 was necessary for fitting the data. Differences in values across experiments appeared mostly non-systematic, and partial data usage did not yield consistently systematic parameter migrations. These findings suggest that fault microstructure may complexly alter parameter values during loading beyond what is accounted for in the Coulomb rate-and-state theory. Nonetheless, with the introduction of the scaling parameter, the Coulomb rate-and-state theory effectively captures the fundamental aspects of AE responses to complex controlled loading histories.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230574"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Teleseismic evidence for structural heterogeneity in East Japan forearc from seafloor S-net data 来自海底S-net资料的东日本弧构造非均质性远震证据
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230579
Motoya Suzuki, Dapeng Zhao, Genti Toyokuni, Ryota Takagi
{"title":"Teleseismic evidence for structural heterogeneity in East Japan forearc from seafloor S-net data","authors":"Motoya Suzuki,&nbsp;Dapeng Zhao,&nbsp;Genti Toyokuni,&nbsp;Ryota Takagi","doi":"10.1016/j.tecto.2024.230579","DOIUrl":"10.1016/j.tecto.2024.230579","url":null,"abstract":"<div><div>We measure and analyze 4381 P-wave and 4307 S-wave arrival times of 48 teleseismic events recorded at 150 stations of a permanent seafloor seismic network (S-net) installed in the outer-rise and forearc region off East Japan. The obtained relative travel-time residuals amounting to ∼3 s at the S-net stations are generally negative on the incoming Pacific and Philippine Sea plates and positive on the continental Okhotsk plate, which reflect high and low seismic velocities, respectively. This pattern is generally consistent with previous results on the seismic velocity structure of the crust and upper mantle beneath the East Japan forearc and the outer-rise area. Large early arrivals (∼2.0 s) appear in the southern part of the S-net for the teleseismic events in the southwestern direction, which are mainly due to southwestward steepening of the subducting Pacific slab beneath Kanto. In the study region, the Pacific slab is the most significant anomaly with a thickness of ∼90 km and a seismic velocity of 5–6 % higher than that of the surrounding mantle. Early arrivals (∼1.5 s) also appear at the S-net stations off South Hokkaido, which are caused by northwestward steepening of the Pacific slab beneath the Tohoku-Hokkaido junction area. These results shed new light on the structural heterogeneity and subduction dynamics of the East Japan arc.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230579"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Moment tensors for small earthquakes and the stress regime in the mid-Atlantic United States 美国中大西洋地区小地震的矩张量和应力状态
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230582
Kyle Homman, Andrew Nyblade
{"title":"Moment tensors for small earthquakes and the stress regime in the mid-Atlantic United States","authors":"Kyle Homman,&nbsp;Andrew Nyblade","doi":"10.1016/j.tecto.2024.230582","DOIUrl":"10.1016/j.tecto.2024.230582","url":null,"abstract":"<div><div>Focal mechanisms for small magnitude earthquakes (M ∼ 1.3–4.1) in the mid-Atlantic region of the United States have been determined using a double-couple moment tensor inversion procedure. The 26 new focal mechanisms obtained, when combined with previously published mechanisms, show a pattern of reverse faulting in the easternmost portion of the study area and strike-slip faulting in the west, consistent with previous studies. The change in focal mechanisms from east to west helps to constrain the geographic location of the east-west transition in the stress regime to a NE-SW area within central Pennsylvania within proximity of the Allegheny Front. Stress inversions performed to constrain variations in the stress state across the region show that the maximum compressive stress varies only slightly, but that the near-vertical stress is the minimum compressive stress in the east and transitions to the intermediate compressive stress in the west, as expected for an east-west transition in reverse to strike-slip faulting. Analysis of driving forces causing the stress change suggests that tectonic terrane structure, glacial isostatic adjustment, and changes in gravitational potential energy have little effect on the stress field in this region, leaving the interaction of sublithospheric mantle flow with the eastern edge of the Laurentian cratonic lithosphere beneath central Pennsylvania as a primary explanation. The cratonic lithospheric keel may cause a deflection in mantle flow, thereby changing the stress field enough so that the magnitude of the vertical stress in relation to the minimum horizontal stress results in strike-slip as opposed to reverse faulting.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230582"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Numerical modelling of lithosphere-asthenosphere interaction and intraplate deformation in the Gulf of Guinea 几内亚湾岩石圈-岩石圈相互作用和板块内变形的数值模拟
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230581
Jaime Almeida , Hamzeh Mohammadigheymasi , Marta Neres , Stéphanie Dumont
{"title":"Numerical modelling of lithosphere-asthenosphere interaction and intraplate deformation in the Gulf of Guinea","authors":"Jaime Almeida ,&nbsp;Hamzeh Mohammadigheymasi ,&nbsp;Marta Neres ,&nbsp;Stéphanie Dumont","doi":"10.1016/j.tecto.2024.230581","DOIUrl":"10.1016/j.tecto.2024.230581","url":null,"abstract":"<div><div>To present day, the phenomenon of intraplate deformation and its associated earthquakes remain elusive. In this work, we argue that intraplate deformation may result from the interaction between lithospheric and upper mantle dynamic processes. To this extent, we targeted the Gulf of Guinea and adjacent Western Africa, a region with both low plate velocities and clear asthenosphere dynamics, allowing us to isolate the individual underlying dynamic constraints which govern intraplate deformation. Thus, here we present 3D numerical geodynamic models of the asthenosphere-lithosphere interaction in the Gulf of Guinea, ran with the state-of-the-art modelling code LaMEM. We employ different initial/boundary conditions such as: (a) identical vs different spreading rates for the varying segments of the Atlantic mid-ocean ridge, (b) the presence/absence of weak zones (e.g., the Romanche/Central-African shear zones), and (c) the effect exerted by an active mantle plume, with a varying ascension velocity. Seismicity patterns was used to evaluate the models and their validity. Our results suggest that intraplate deformation within the Gulf of Guinea is influenced by the spreading rate of the mid-ocean ridge, with stress being localized around the ocean-continent transition and existing shear zones. They also suggest that the existence of an underlying stress source (e.g., a mantle plume) beneath the Cameroon region is crucial to explain the epicenter distribution/deformation in the region.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230581"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Slip instability of dilatant and fluid-saturated faults 膨胀断层和流体饱和断层的滑动不稳定性
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230598
Cheng Mei
{"title":"Slip instability of dilatant and fluid-saturated faults","authors":"Cheng Mei","doi":"10.1016/j.tecto.2024.230598","DOIUrl":"10.1016/j.tecto.2024.230598","url":null,"abstract":"<div><div>The mechanisms of slip instabilities of dilatant and fluid-saturated faults remain controversial, particularly in low-permeability environments. Using a rate and state friction model including the effects of dilatancy, we conduct a linearized stability analysis of a one-dimensional spring-slider model and reexamine the critical stiffness (<span><math><msub><mi>k</mi><mi>c</mi></msub></math></span>) of the fault zone as a function of fluid diffusivity and dilatancy factor. Our analytical results indicate that under fully-drained conditions, <span><math><msub><mi>k</mi><mi>c</mi></msub></math></span> is independent of dilatancy factor, while under poorly-drained conditions, <span><math><msub><mi>k</mi><mi>c</mi></msub></math></span> depends on dilatancy factor and fluid diffusivity. Both analytical and numerical results show that a non-negative <span><math><msub><mi>k</mi><mi>c</mi></msub></math></span> always exists, even for highly-dilatant and poorly-drained faults where <span><math><msub><mi>k</mi><mi>c</mi></msub></math></span> is proportional to fluid diffusivity. This implies that dilatancy does not alter the inherent (in)stability of fault slip, and that a sufficiently low system stiffness can always produce unstable fault slips without a critical pore pressure or critical dilatancy factor. These findings may provide new insights into effects of dilatancy on fault instability. The numerical results further illustrate that the fault slip acceleration tends to be significantly suppressed by increasing dilatancy factor and decreasing fluid diffusivity. These results may explain ubiquitous slow-slip events on natural faults that vary in length.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230598"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Influence of seismometer misorientation on crustal thickness and Vp/Vs estimated with teleseismic P-wave receiver functions 地震仪方位偏差对用远震纵波接收函数估计地壳厚度和Vp/Vs的影响
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230577
Diogo Farrapo Albuquerque , Marcelo Peres Rocha , George Sand França , Marcelo Bianchi , Reinhardt A. Fuck
{"title":"Influence of seismometer misorientation on crustal thickness and Vp/Vs estimated with teleseismic P-wave receiver functions","authors":"Diogo Farrapo Albuquerque ,&nbsp;Marcelo Peres Rocha ,&nbsp;George Sand França ,&nbsp;Marcelo Bianchi ,&nbsp;Reinhardt A. Fuck","doi":"10.1016/j.tecto.2024.230577","DOIUrl":"10.1016/j.tecto.2024.230577","url":null,"abstract":"<div><div>We analyzed the influence of seismometer misorientation on crustal thickness and Vp/Vs estimated with teleseismic P-wave receiver functions simulating orientation errors during the rotation procedure of the horizontal components from true NS-EW (North-South, East-West) to RT (Radial-Tangential) coordinate system. During this procedure, we incrementally added 5° to the azimuth of the NS and EW components. The influence of the misorientation on P-wave teleseismic receiver functions was confirmed by the analysis of different parameters, such as normalized amplitude of P, Ps and multiple phases, reproduction of the radial component and crustal thickness and Vp/Vs estimates. This analysis indicated |45°| as the maximum misorientation allowed to consider crustal thickness, Vp/Vs, and geophysical interpretation reliable. For misorientations larger than |75°|, the reliability is low, and the data could be considered inappropriate for receiver function technique and crustal studies. We also identified some signs of misorientation: P-wave polarity inversion in radial RF trace combined with strong P-wave troughs in the tangential one, low Ps-wave normalized amplitude, reproduction of the radial lower than 90 % for most receiver function traces, and large standard deviations in crustal thickness and Vp/Vs estimates. Since most of the seismometers deployed at Brazilian Seismographic Network were well oriented (only three have orientation errors larger than 45°), in general, previous studies that used data from those stations for estimating crustal thickness and Vp/Vs using the H-k method are reliable. However, in future versions of Brazilian crustal models, the estimates using stations with misorientation larger than |45°| must be recalculated applying an azimuth correction. Finally, since normalized amplitudes are very sensitive to misorientation, the analysis of P and Ps amplitudes in radial receiver functions can be used as a tool to estimate seismometer orientation error and other issues affecting station gain.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230577"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Seismotectonic assessment of the High Atlas orogen: Implications for the 8 September Mw 6.8 El-Haouz earthquake 高阿特拉斯造山带地震构造评价:对9月8日El-Haouz地震的启示
IF 2.7 3区 地球科学
Tectonophysics Pub Date : 2025-01-24 DOI: 10.1016/j.tecto.2024.230573
Hamza Skikra , Abdelali Fadil , Youness Ouassanouan , Khalid Lakhouidsi , Abdelilah Tahayt , Abderrahmane Soulaimani , Lahcen El Moudnib
{"title":"Seismotectonic assessment of the High Atlas orogen: Implications for the 8 September Mw 6.8 El-Haouz earthquake","authors":"Hamza Skikra ,&nbsp;Abdelali Fadil ,&nbsp;Youness Ouassanouan ,&nbsp;Khalid Lakhouidsi ,&nbsp;Abdelilah Tahayt ,&nbsp;Abderrahmane Soulaimani ,&nbsp;Lahcen El Moudnib","doi":"10.1016/j.tecto.2024.230573","DOIUrl":"10.1016/j.tecto.2024.230573","url":null,"abstract":"<div><div>The Moroccan High Atlas is a slowly deforming intracontinental orogenic belt, characterized by moderate and diffuse seismic activity. The 8 September 2023 Mw 6.8 El-Haouz earthquake, one of the most powerful quakes recorded in North Africa, has intensified investigations into the seismotectonics of the High Atlas. This study examines seismotectonic patterns in the High Atlas using seismological and geodetic data to better understand the mechanisms driving such seismic events. Seismological data indicate active shortening in the region, contributing to ongoing mountain building. Present-day deformation is partitioned between thrust and strike-slip faulting, with NW-SE compression, consistent with the broader stress field in North Africa. Frequency-magnitude distribution analysis indicates that the Western High Atlas exhibited low b-values, slightly lower than 1, in the eight years preceding the El-Haouz earthquake, with an low b-value (∼ 0.8 ± 0.1) near the epicenter, suggesting high stress accumulation in the region. GNSS observations reveal that the High Atlas experiences low geodetic velocities compared with the Rif collision belt, with displacements below 1 mm/year. Notably, the axial zone of the Western High Atlas exhibits an uplift of 1.1 mm/yr. The combination of moderate shortening and relatively higher uplift prior to the El-Haouz earthquake suggests that present-day deformation in the Western High Atlas is predominantly accommodated by the reactivation of inherited faults in the axial zone. This is further corroborated by the distribution of aftershocks, which supports a steeply dipping seismogenic fault manifested by the Tizi n'Test Fault.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"895 ","pages":"Article 230573"},"PeriodicalIF":2.7,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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