Tectonophysics最新文献

Geological reconstruction based on metamorphic thermal analysis and utility in active fault research

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-21 DOI: 10.1016/j.tecto.2025.230759

Hiroshi Mori , Takafumi Shinya , Yuho Hayakawa , Kaho Nobuhara , Ken Yamaoka , Tomoki Taguchi , Tetsuya Tokiwa , Kazuhiro Ozawa , Daichi Murakami , Wataru Tanaka , Yurie Tsukishima

Reconstructing the geological configuration around a major fault prior to its movement is essential for understanding regional tectonics and estimating total fault displacement. We aimed to reconstruct and validate the geological distribution across the Itoigawa–Shizuoka Tectonic Line (ISTL), central Japan, based on a metamorphic thermal analysis of the surrounding basement metamorphic rocks. The thermal structure of metamorphic rocks south of the ISTL shows a temperature increase in two directions: from east to west toward the western margin of the geologic body, and from south to north toward the intruded plutonic body. The east–west thermal structure closely resembles that of the metamorphic rocks north of the ISTL. Based on this regional-scale correspondence in metamorphic thermal structure across the ISTL, the reconstructed pre-faulting configuration suggests that the now discontinuously exposed plutonic bodies to the south and north of the ISTL were originally a single plutonic body before faulting. The extent of the intrusive magma body, inferred from the estimated thermal structure and modeled through intrusion thermal analysis, is consistent with the north–south span of the reconstructed plutonic body. This consistency supports the validity of the reconstruction based on regional thermal structure. Furthermore, our results are consistent with the strike–slip faulting along the ISTL having occurred after the intrusion of magma at approximately 10 Ma and caused a total horizontal displacement of approximately 13 km. Thus, analyzing the metamorphic temperatures of basement rocks offers a novel and effective approach for reconstructing pre-faulting geological relationships and for investigating fault history over geological timescales.

{"title":"Geological reconstruction based on metamorphic thermal analysis and utility in active fault research","authors":"Hiroshi Mori , Takafumi Shinya , Yuho Hayakawa , Kaho Nobuhara , Ken Yamaoka , Tomoki Taguchi , Tetsuya Tokiwa , Kazuhiro Ozawa , Daichi Murakami , Wataru Tanaka , Yurie Tsukishima","doi":"10.1016/j.tecto.2025.230759","DOIUrl":"10.1016/j.tecto.2025.230759","url":null,"abstract":"<div><div>Reconstructing the geological configuration around a major fault prior to its movement is essential for understanding regional tectonics and estimating total fault displacement. We aimed to reconstruct and validate the geological distribution across the Itoigawa–Shizuoka Tectonic Line (ISTL), central Japan, based on a metamorphic thermal analysis of the surrounding basement metamorphic rocks. The thermal structure of metamorphic rocks south of the ISTL shows a temperature increase in two directions: from east to west toward the western margin of the geologic body, and from south to north toward the intruded plutonic body. The east–west thermal structure closely resembles that of the metamorphic rocks north of the ISTL. Based on this regional-scale correspondence in metamorphic thermal structure across the ISTL, the reconstructed pre-faulting configuration suggests that the now discontinuously exposed plutonic bodies to the south and north of the ISTL were originally a single plutonic body before faulting. The extent of the intrusive magma body, inferred from the estimated thermal structure and modeled through intrusion thermal analysis, is consistent with the north–south span of the reconstructed plutonic body. This consistency supports the validity of the reconstruction based on regional thermal structure. Furthermore, our results are consistent with the strike–slip faulting along the ISTL having occurred after the intrusion of magma at approximately 10 Ma and caused a total horizontal displacement of approximately 13 km. Thus, analyzing the metamorphic temperatures of basement rocks offers a novel and effective approach for reconstructing pre-faulting geological relationships and for investigating fault history over geological timescales.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"907 ","pages":"Article 230759"},"PeriodicalIF":2.7,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870353","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

A zoning model for seismic hazard analysis of Finland and adjacent areas: A fusion of seismological and geological data

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-21 DOI: 10.1016/j.tecto.2025.230757

Päivi Mäntyniemi , Ludovic Fülöp , Kati Oinonen , Niina Junno , Emilia Kosonen , Annakaisa Korja

We present a new seismic zoning model for the territory of Finland and adjacent areas in northern Europe for the purpose of seismic hazard mapping. The target region, mostly situated in the stable continental region of the Fennoscandian Shield, exhibits predominantly earthquakes below moment magnitude 3.0. We have delineated area seismic source zones by fusing seismological, geological, and geophysical data, and tectonic boundaries. The approach is warranted to find sufficient argumentation on the zoning due to the poor to non-existent seismicity data in the eastern and southeastern part of our target region. We have addressed the subjectivity included in delineation of zone boundaries by combining the preliminary delineations of four expert groups into a model with three levels of details: macro-, meso- and microlevel. We compare the new microlevel zoning with the regional zoning models of 2015 and 2016 and all the three zonings with the respective zonings of the 2020 European Seismic Hazard Model. We argue that the new zoning model SZ2025FI provides a sufficient basis for seismic hazard mapping on national and regional scales, as well as European and global mapping initiatives.

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引用次数: 0

A review of velocity fields in fault bend folding kinematic models: General algorithm for computational application

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-21 DOI: 10.1016/j.tecto.2025.230758

Ernesto Cristallini

This study presents a comprehensive approach to fault-related folding by integrating multiple kinematic models into a unified framework. Fault-parallel flow, inclined shear, classical fault-bend folding (flexural-slip fault bend folding), and backlimb trishear are combined within this methodology. Hanging-wall particle velocities are computed based on the asymmetry of the axial trace relative to the bisector of each fault bend. A backlimb trishear zone for smoothing deformation over sharp fault bends can be added to produce a curved shape in the resulting folds. Validation against analog physical experiments and natural examples demonstrates a strong agreement, accurately capturing the geometry of natural folds. By incorporating asymmetry angles and backlimb trishear apical angles, the model successfully reproduces complex structures, including folds with progressive limb rotation. Additionally, it enhances classical fault-bend folding, inclined shear, and fault-parallel flow models by enabling independent balancing of each fault bend, facilitating the development of curved and geologically realistic folds. Implemented in Python, the proposed algorithm allows users to test it on simple fold structures, serving as a foundation for integration into more advanced software. Its computational efficiency and reversibility make it particularly well-suited for iterative model adjustments to fit real data. This integration of fault-bend fold models represents a significant advancement, offering a robust framework for simulating complex geological structures consistent with seismic profiles, well data, and field observations. Moreover, by adjusting the slip direction, the model can be adapted to accommodate both reverse and normal faulting, making it applicable to a wide range of geological scenarios. Strain in the models can be effectively tracked by embedding objects of known shape, such as circles or a regular grid, in the undeformed state.

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引用次数: 0

Interseismic deformation and 3D kinematic reconstruction of the Balapur Fault, NW Himalaya: Insights from InSAR and gravity data

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-20 DOI: 10.1016/j.tecto.2025.230744

Asrar Ahmad Rather , Syed Kaiser Bukhari

The Balapur Fault is one of the most studied faults within the Kashmir Basin due to its possible role in future seismicity and its proximity to the population center in the NW Himalaya. This study utilizes the multidisciplinary approach of Persistent Scatterer InSAR and gravity analysis to study the surface kinematics and subsurface characteristics of the fault structure. Over 200 Sentinel-1 scenes acquired in ascending and descending geometries between 2014 and 2023 were analyzed to derive interseismic deformation patterns, yielding mean Line-of-Sight rates ranging from 1 ± 0.3 mm/yr to 2 ± 0.4 mm/yr. LOS data were decomposed into east-west and vertical components, revealing uplift rates of approximately 2 mm/yr in agreement with the known shortening rates. Cross-sectional velocity analyses along the entire fault length (both mapped and inferred) indicate uniform fault activity, although a detailed fault-locking inversion reveals along-strike heterogeneities. Specifically, Monte Carlo simulations integrated within the inversion framework quantify uncertainties in fault parameters and indicate that while most segments lock at depths of 12–13 km, the northern Segment 1 appears to be locked at greater depths (∼16 km), consistent with a deepening décollement observed in the region. Continuous GPS station data from 3 nearby locations is further utilized to cross-validate and calibrate InSAR-derived displacement rates. Gravity data acquisition and processing, including Complete Bouguer anomaly and Total Horizontal Derivative mapping, provide further constraints on the subsurface structure, delineating fault strike and revealing contrasting density gradients. 3D model inversion of the gravity data uncovers three prominent zones of discontinuity corresponding to the main fault and its subsidiary branches, indicating a high dip angle (>60°) and the deep-rooted nature of the fault. This integrated approach enhances our understanding of fault kinematics and locking behavior in the Balapur Fault and demonstrates the utility of combining geodetic and gravimetric methods for comprehensive seismic hazard assessment.

{"title":"Interseismic deformation and 3D kinematic reconstruction of the Balapur Fault, NW Himalaya: Insights from InSAR and gravity data","authors":"Asrar Ahmad Rather , Syed Kaiser Bukhari","doi":"10.1016/j.tecto.2025.230744","DOIUrl":"10.1016/j.tecto.2025.230744","url":null,"abstract":"<div><div>The Balapur Fault is one of the most studied faults within the Kashmir Basin due to its possible role in future seismicity and its proximity to the population center in the NW Himalaya. This study utilizes the multidisciplinary approach of Persistent Scatterer InSAR and gravity analysis to study the surface kinematics and subsurface characteristics of the fault structure. Over 200 Sentinel-1 scenes acquired in ascending and descending geometries between 2014 and 2023 were analyzed to derive interseismic deformation patterns, yielding mean Line-of-Sight rates ranging from 1 ± 0.3 mm/yr to 2 ± 0.4 mm/yr. LOS data were decomposed into east-west and vertical components, revealing uplift rates of approximately 2 mm/yr in agreement with the known shortening rates. Cross-sectional velocity analyses along the entire fault length (both mapped and inferred) indicate uniform fault activity, although a detailed fault-locking inversion reveals along-strike heterogeneities. Specifically, Monte Carlo simulations integrated within the inversion framework quantify uncertainties in fault parameters and indicate that while most segments lock at depths of 12–13 km, the northern Segment 1 appears to be locked at greater depths (∼16 km), consistent with a deepening décollement observed in the region. Continuous GPS station data from 3 nearby locations is further utilized to cross-validate and calibrate InSAR-derived displacement rates. Gravity data acquisition and processing, including Complete Bouguer anomaly and Total Horizontal Derivative mapping, provide further constraints on the subsurface structure, delineating fault strike and revealing contrasting density gradients. 3D model inversion of the gravity data uncovers three prominent zones of discontinuity corresponding to the main fault and its subsidiary branches, indicating a high dip angle (>60°) and the deep-rooted nature of the fault. This integrated approach enhances our understanding of fault kinematics and locking behavior in the Balapur Fault and demonstrates the utility of combining geodetic and gravimetric methods for comprehensive seismic hazard assessment.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"907 ","pages":"Article 230744"},"PeriodicalIF":2.7,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859884","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

Tectonic tremor source depths in relation to subduction zone structure in northern Cascadia

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-20 DOI: 10.1016/j.tecto.2025.230752

Madison Bombardier , John F. Cassidy , Stan E. Dosso , Honn Kao

Tectonic tremor occurs in frequent episodes throughout northern Cascadia, typically during slow slip events deep in the subduction zone. Adequately constraining tremor source depths is a challenge associated with using low-amplitude, emergent waveforms. In this study, we present a tremor catalogue with improved depth resolution computed using the differential traveltime Bayesian inversion method, where tremor sources are represented as 3D probability distributions. We examine tremor source depths throughout northern Cascadia in relation to low-frequency earthquakes (LFEs) and key features in the subduction zone imaged using receiver-function analysis. We show that the highest concentrations of tremor are 5–10 km shallower than LFEs everywhere in northern Cascadia. We also find that neither tremor nor LFEs localize consistently to the top of the oceanic crust, which is often interpreted to represent the subduction fault. Rather, tremor localizes throughout a volume corresponding to the deep accretionary complex at depths deeper than 15 km. Where the accretionary complex appears to be vertically-truncated by forearc terranes, such as the Olympic Accretionary Complex in Washington, the tremor depth distribution is similarly vertically restricted. Depth trends of tremor and LFEs may indicate deformation within and above the downgoing plate that is not represented in current models of the subduction zone. We suggest that tremor-generating processes may involve multiple mechanisms that are partly dependent on their distance from the downgoing plate and occur within the compositionally- and structurally-heterogeneous mélange of the deep accretionary complex.

{"title":"Tectonic tremor source depths in relation to subduction zone structure in northern Cascadia","authors":"Madison Bombardier , John F. Cassidy , Stan E. Dosso , Honn Kao","doi":"10.1016/j.tecto.2025.230752","DOIUrl":"10.1016/j.tecto.2025.230752","url":null,"abstract":"<div><div>Tectonic tremor occurs in frequent episodes throughout northern Cascadia, typically during slow slip events deep in the subduction zone. Adequately constraining tremor source depths is a challenge associated with using low-amplitude, emergent waveforms. In this study, we present a tremor catalogue with improved depth resolution computed using the differential traveltime Bayesian inversion method, where tremor sources are represented as 3D probability distributions. We examine tremor source depths throughout northern Cascadia in relation to low-frequency earthquakes (LFEs) and key features in the subduction zone imaged using receiver-function analysis. We show that the highest concentrations of tremor are 5–10 km shallower than LFEs everywhere in northern Cascadia. We also find that neither tremor nor LFEs localize consistently to the top of the oceanic crust, which is often interpreted to represent the subduction fault. Rather, tremor localizes throughout a volume corresponding to the deep accretionary complex at depths deeper than 15 km. Where the accretionary complex appears to be vertically-truncated by forearc terranes, such as the Olympic Accretionary Complex in Washington, the tremor depth distribution is similarly vertically restricted. Depth trends of tremor and LFEs may indicate deformation within and above the downgoing plate that is not represented in current models of the subduction zone. We suggest that tremor-generating processes may involve multiple mechanisms that are partly dependent on their distance from the downgoing plate and occur within the compositionally- and structurally-heterogeneous mélange of the deep accretionary complex.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"907 ","pages":"Article 230752"},"PeriodicalIF":2.7,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143875041","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

Revisiting the reservoir-triggered seismicity of Koyna India using near-source seismological observations and relationship with reservoir water level changes

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-15 DOI: 10.1016/j.tecto.2025.230743

Anup K. Sutar , Sunil Rohilla , Himanshu Chaube , Charulata Chaudhari

The Koyna-Warna region in western Maharashtra, India, continues to experience seismic activity, even six decades after the impoundment of Koyna Reservoir. The seismicity of Koyna region is primarily linked to the Donichawadi fault zone, which ruptured the surface during the 1967 M6.3 Koyna earthquake. In 2017, a 3 km-deep scientific borehole (Koyna Pilot Borehole, KFD1) was drilled, revealing subsurface fault characteristics through downhole geophysical logs. The present study utilizes data acquired from a near-field, 5-station broadband seismological network surrounding KFD1, which has been operational since January 2022. The analysis identifies a zone of recurrent earthquakes within a 1–2 km radius of KFD1, where 13 M > 2 earthquakes occurred over 21 months, recurring approximately every four months. Precise earthquake locations, obtained using an updated velocity model of the Koyna area, delineate four distinct sub-zones within the Koyna fault zone. The northernmost sub-zone produces stronger, shallower earthquakes (4–8 km deep) with a strike-slip faulting mechanism. The second sub-zone generates deeper earthquakes (7–10 km deep) with a combination of normal and strike-slip faulting mechanisms. The third sub-zone experiences recurrent seismic activity at 4–8 km depth, while the southernmost sub-zone produces smaller, shallower earthquakes (2–4 km deep). Identifying these sub-zones helps in understanding the underlying tectonic processes of the Koyna region.

Further analysis reveals a positive correlation between the water level fluctuation of Koyna reservoir and earthquake occurrence within the region. A statistical analysis of earthquake records from 2005 to 2017 yielded a correlation coefficient of 0.15. However, analysis focusing on recent, near-source seismic data of 2022 demonstrates an enhanced correlation of 0.25. These findings underscore the critical role of continued near-source monitoring in refining our understanding of reservoir-triggered seismicity in the Koyna region.

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引用次数: 0

Control of inherited structures on deformation and surface uplift: Crustal-scale analogue modelling with implications for the European eastern Southern Alps

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-12 DOI: 10.1016/j.tecto.2025.230736

Anna-Katharina Sieberer , Ernst Willingshofer , Thomas Klotz , Hugo Ortner , Hannah Pomella

We use crustal-scale physical analogue modelling to investigate the effect of mechanical and structural inheritance on the surface uplift of fold-and-thrust belts. Our study includes inversion of a pre-defined basin and platform structure of varying geometry and strength as well as that of a structurally controlled heterogeneity at the model-base. Our experiments represent multiply deformed continental crust, as it is the case for the eastern Southern Alps (ESA) of Europe, where lateral strength variations stem from Permian volcanic and plutonic rocks located within the northern Trento platform. Basal structural heterogeneity in the models represents Permian paleo-faults bordering volcanic rocks, reactivated under various tectonic regimes up to the present-day. Crustal composition and structure variations are embedded in a structural frame of an extensional platform and basin differentiation related to Triassic/Jurassic extension. We present a novel approach of comparing model surface uplift patterns with exhumation data from regional thermochronological studies of the ESA, enabling interpretations of first-order tectonic processes governing specific exhumation patterns. Modelling results demonstrate that pre-defined structures control timing and patterns of uplift of the evolving fold-and-thrust belt and stronger crustal domains and/or basement heterogeneities localise deformation. Besides prevalent in-sequence deformation, out-of-sequence reactivation of specific faults is coeval with slip on multiple faults, influencing spatial and temporal surface uplift. Two distinct end-members of surface uplift patterns emerge: “differential” versus “continuous”. Inherited basement structures control strain localisation and promote “differential” surface uplift, where the rear of the fold-and-thrust belt experiences little surface uplift and uplift is mainly focused above the inherited basement structure, consistent with documented plateaus in low-temperature thermochronology data of the western ESA north of the Valsugana fault system between Jurassic and Neogene times. Contrarily, experiments featuring relative stronger upper crustal domains show “continuous” surface uplift, correlating with continuous exhumation over the last ∼15 Ma according to geochronology data.

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引用次数: 0

High-rate GNSS detects the near- and far-field effects of displacements during the 2011 Tohoku Mw9.0 earthquake

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-11 DOI: 10.1016/j.tecto.2025.230742

Peiliang Xu

Although there are a great number of research and publications on empirical amplitude, distance and magnitude scaling laws, none of them have ever considered the near- and far-field effects of displacement functions of seismic waves. We use the GEONET GNSS data collected from the 2011 Tohoku Mw9.0 earthquake to resolve the inconsistency between empirical amplitude, distance and magnitude scaling laws and theoretical displacement functions. We find that the high-rate dynamical GNSS PPP displacements clearly detect the near- and far-field amplitude distance scaling effects during the 2011 Tohoku Mw9.0 earthquake. The GNSS PPP coseismic displacements decay much more rapidly than theoretically expected in the near field but likely more slowly in the far field. If the near-field effect of displacements is not correctly taken into account, the decay rate will be significantly underestimated, implying that magnitudes of earthquakes will be significantly underestimated from near-field data with profound negative impact in earthquake early warning and hazard assessment.

引用次数: 0

Revealing strong earthquake risks in seismic gaps of the Sichuan-Yunnan region based on crustal-scale magnetic inversion

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-08 DOI: 10.1016/j.tecto.2025.230741

Weinan Wang , Liguo Jiao , Jiyao Tu , Yu Lei , Junhao Zhao , Zhaobo He , Kunjie Sun , Huaran Chen

The physical property structure of the crustal medium exerts a significant control on the formation of seismic gaps and the associated strong earthquake risk. Using EMAG2-v3 magnetic anomaly grids and 5561 field outcrop rock magnetic susceptibility data, we inverted the 0.1 × 0.1⁰ 3D magnetic structure of the Sichuan-Yunnan region. Based on this structure, we analyzed its influence on regional tectonic deformation and assessed the seismic risks in major seismic gaps. The strong magnetic bodies primarily originate from the NE-trending Neoproterozoic basement of the Sichuan Basin and the finger-like mafic-ultramafic channels in the central Yunnan block formed by the Permian Emeishan plumelets. These mafic components intensify the crust and exert varying degrees of resistance to the extrusion and escape of the Tibetan Plateau, indicating that the early strong magnetic basement plays a more significant role in craton strengthening and stabilization compared to the later mantle plume. Based on magnetic boundaries and magnetic intensity, combined with stress accumulation and fault coupling, the following seismic risks are identified: The southernmost segment of the Longmenshan Fault Zone and the Mianning-Xichang section, especially its southern half near Xichang, are at high risk of strong earthquakes (M_S 7+) and moderate-strong earthquakes (M_S 6-M_S 7), respectively. The Bamei-Kangding section has a moderate earthquake (<M_S 6) risk. The Dayi seismic gap shows no short-term strong earthquake risk but may shift to the Pujiang-Xinjin Fault Zone ∼60 km southeast.

{"title":"Revealing strong earthquake risks in seismic gaps of the Sichuan-Yunnan region based on crustal-scale magnetic inversion","authors":"Weinan Wang , Liguo Jiao , Jiyao Tu , Yu Lei , Junhao Zhao , Zhaobo He , Kunjie Sun , Huaran Chen","doi":"10.1016/j.tecto.2025.230741","DOIUrl":"10.1016/j.tecto.2025.230741","url":null,"abstract":"<div><div>The physical property structure of the crustal medium exerts a significant control on the formation of seismic gaps and the associated strong earthquake risk. Using EMAG2-v3 magnetic anomaly grids and 5561 field outcrop rock magnetic susceptibility data, we inverted the 0.1 × 0.1<sup>0</sup> 3D magnetic structure of the Sichuan-Yunnan region. Based on this structure, we analyzed its influence on regional tectonic deformation and assessed the seismic risks in major seismic gaps. The strong magnetic bodies primarily originate from the NE-trending Neoproterozoic basement of the Sichuan Basin and the finger-like mafic-ultramafic channels in the central Yunnan block formed by the Permian Emeishan plumelets. These mafic components intensify the crust and exert varying degrees of resistance to the extrusion and escape of the Tibetan Plateau, indicating that the early strong magnetic basement plays a more significant role in craton strengthening and stabilization compared to the later mantle plume. Based on magnetic boundaries and magnetic intensity, combined with stress accumulation and fault coupling, the following seismic risks are identified: The southernmost segment of the Longmenshan Fault Zone and the Mianning-Xichang section, especially its southern half near Xichang, are at high risk of strong earthquakes (<em>M</em><sub>S</sub> 7+) and moderate-strong earthquakes (<em>M</em><sub>S</sub> 6-<em>M</em><sub>S</sub> 7), respectively. The Bamei-Kangding section has a moderate earthquake (<<em>M</em><sub>S</sub> 6) risk. The Dayi seismic gap shows no short-term strong earthquake risk but may shift to the Pujiang-Xinjin Fault Zone ∼60 km southeast.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"906 ","pages":"Article 230741"},"PeriodicalIF":2.7,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143807622","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

Strength of the lithosphere in Graham Land region (Antarctic Peninsula), derived from geological and geophysical data

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-04-08 DOI: 10.1016/j.tecto.2025.230727

Fernando Linsalata , Daniele Melini , Giorgio Spada

We explore the lithospheric strength in the Graham Land region of the Antarctic Peninsula (AP) through the integration of geological and geophysical data with numerical modeling. We used GNSS data and Glacial Isostatic Adjustment (GIA) models to derive velocity and strain fields, while rheological parameters and geothermal heat flow (GHF) provided constraints for calculating the lithospheric strength profile. The methodology incorporates the Yield Strength Envelope (YSE), a framework that characterizes lithospheric strength at varying depths by accounting for both brittle and viscous deformation. A key result is a refined model of vertical and horizontal velocity fields, revealing a dominant uplift with peak rates reaching approximately 12.7 mm yr

^{- 1}

. The strength model reveals a lithosphere with significant thermal variations, which are influenced by substrate composition and regional geodynamic processes. The analysis underscores that the lithosphere's mechanical behavior is strongly impacted by regional tectonic interactions and elevated geothermal heat flow. This work enhances understanding of Antarctic lithospheric dynamics, with implications for geological evolution and global climate change studies.

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引用次数: 0