Pub Date : 2026-04-10Epub Date: 2026-02-25DOI: 10.1016/j.tecto.2026.231141
Ruiya Bai , Yingquan Sang , Canyang Ding , Chengli Liu , Lingling Ye , Thorne Lay , Neng Xiong , Xiong Xiong
The rupture process of the 2024 Hualien MW 7.4 earthquake was investigated through a joint inversion of seismic and geodetic datasets, revealing a complex multi-faulting event involving four fault segments that ruptured coseismically. The rupture initiated on a southeast-dipping reverse fault (F1) at a depth of 20 km. Six seconds later, slip propagated onto a conjugate reverse fault (F2), intersecting F1 at a depth of 34.5 km. Subsequent ruptures occurred on fault segments to the north; F3 at 20 s, with normal faulting mechanism, followed by overlying thrust fault F4 at approximately 33 s. The rupture propagated progressively toward the northeast, extending roughly 80 km along strike, with an average rupture velocity of ∼2.5 km/s. The heterogeneous slip distributions have peak slip of ∼4 m near the intersection of F1 and F2, accompanied by complementary aftershock patterns. The total seismic moment is estimated as 1.53 × 1020 N·m, with the majority released within the first 35 s, predominantly on F1 and F2. Notably, we identified depth-dependent rise time patterns on the main fault, with longer rise times at shallower depths. This study provides new insights into multi-fault interactions during a major earthquake rupture, particularly the dynamics of conjugate faulting in continental collision zones, which can guide seismic hazard assessments and more realistic simulations of complex suture zone fault behavior.
{"title":"Complex rupture of the 2 April 2024 MW 7.4 Hualien earthquake inferred from seismic and geodetic observations","authors":"Ruiya Bai , Yingquan Sang , Canyang Ding , Chengli Liu , Lingling Ye , Thorne Lay , Neng Xiong , Xiong Xiong","doi":"10.1016/j.tecto.2026.231141","DOIUrl":"10.1016/j.tecto.2026.231141","url":null,"abstract":"<div><div>The rupture process of the 2024 Hualien <em>M</em><sub><em>W</em></sub> 7.4 earthquake was investigated through a joint inversion of seismic and geodetic datasets, revealing a complex multi-faulting event involving four fault segments that ruptured coseismically. The rupture initiated on a southeast-dipping reverse fault (F1) at a depth of 20 km. Six seconds later, slip propagated onto a conjugate reverse fault (F2), intersecting F1 at a depth of 34.5 km. Subsequent ruptures occurred on fault segments to the north; F3 at 20 s, with normal faulting mechanism, followed by overlying thrust fault F4 at approximately 33 s. The rupture propagated progressively toward the northeast, extending roughly 80 km along strike, with an average rupture velocity of ∼2.5 km/s. The heterogeneous slip distributions have peak slip of ∼4 m near the intersection of F1 and F2, accompanied by complementary aftershock patterns. The total seismic moment is estimated as 1.53 × 10<sup>20</sup> N·m, with the majority released within the first 35 s, predominantly on F1 and F2. Notably, we identified depth-dependent rise time patterns on the main fault, with longer rise times at shallower depths. This study provides new insights into multi-fault interactions during a major earthquake rupture, particularly the dynamics of conjugate faulting in continental collision zones, which can guide seismic hazard assessments and more realistic simulations of complex suture zone fault behavior.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"927 ","pages":"Article 231141"},"PeriodicalIF":2.6,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387527","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}
Pub Date : 2026-04-10Epub Date: 2026-02-20DOI: 10.1016/j.tecto.2026.231135
Dominik R. Vlaha , Andrew V. Zuza , Ariuntsetseg Ganbat , Chen Wu , Peter J. Haproff , Victor E. Guevara , A. Alexander G. Webb , Marie C. Genge , Birendra P. Singh
Early Paleozoic plutonism and metamorphism in the Cenozoic Himalayan orogen is correlated with tectono-magmatic events that impacted the margins of the Gondwanan continent. Deciphering the tectonic origin of these Cambrian–Ordovician intrusions is important to better understand the evolution of the Gondwanan and Eurasian continents and initial conditions for Cenozoic Himalayan construction. To address these issues, we integrated geologic observations, whole-rock and Sr-Nd isotope geochemistry, and igneous and detrital zircon geochronology in the Himachal Himalaya along the Chenab, Pin, Sutlej, and Baspa river valleys in northwestern India. The goals of this study are to constrain: (1) the pre-Himalayan tectono-stratigraphic framework of the proto-Tethyan margin; and (2) the geodynamic setting for early Paleozoic peri-Gondwana crustal melting. Geologic, geochronologic, and geochemical data show that ca. 495–463 Ma crustal-derived peraluminous magmas crystallized at moderate to shallow crustal levels, synchronous with a regionally extensive Cambrian–Ordovician hiatus in sedimentation. Cambrian–Cretaceous strata in the Tethyan Himalaya show similar detrital zircon age distributions and evidence of a consistent provenance source via an extensive fluvial system over a broad area of eastern Gondwana. These results, combined with observed structural continuity across the Cambrian–Ordovician unconformity, suggest that the source area for the northern Greater India passive margin did not significantly change due to peri-Gondwanan orogenesis. New and compiled geologic observations, whole-rock and Sr-Nd isotope geochemistry, and igneous and detrital zircon geochronology are consistent with global Paleozoic S-type magmatism along the margins of Gondwana, which may be explained by multiple or a single peri-Gondwanan silicic Large Igneous Province.
{"title":"Early Paleozoic magmatism in the Himalaya linked with a peri-Gondwana silicic large igneous province","authors":"Dominik R. Vlaha , Andrew V. Zuza , Ariuntsetseg Ganbat , Chen Wu , Peter J. Haproff , Victor E. Guevara , A. Alexander G. Webb , Marie C. Genge , Birendra P. Singh","doi":"10.1016/j.tecto.2026.231135","DOIUrl":"10.1016/j.tecto.2026.231135","url":null,"abstract":"<div><div>Early Paleozoic plutonism and metamorphism in the Cenozoic Himalayan orogen is correlated with tectono-magmatic events that impacted the margins of the Gondwanan continent. Deciphering the tectonic origin of these Cambrian–Ordovician intrusions is important to better understand the evolution of the Gondwanan and Eurasian continents and initial conditions for Cenozoic Himalayan construction. To address these issues, we integrated geologic observations, whole-rock and Sr-Nd isotope geochemistry, and igneous and detrital zircon geochronology in the Himachal Himalaya along the Chenab, Pin, Sutlej, and Baspa river valleys in northwestern India. The goals of this study are to constrain: (1) the pre-Himalayan tectono-stratigraphic framework of the proto-Tethyan margin; and (2) the geodynamic setting for early Paleozoic peri-Gondwana crustal melting. Geologic, geochronologic, and geochemical data show that ca. 495–463 Ma crustal-derived peraluminous magmas crystallized at moderate to shallow crustal levels, synchronous with a regionally extensive Cambrian–Ordovician hiatus in sedimentation. Cambrian–Cretaceous strata in the Tethyan Himalaya show similar detrital zircon age distributions and evidence of a consistent provenance source via an extensive fluvial system over a broad area of eastern Gondwana. These results, combined with observed structural continuity across the Cambrian–Ordovician unconformity, suggest that the source area for the northern Greater India passive margin did not significantly change due to peri-Gondwanan orogenesis. New and compiled geologic observations, whole-rock and Sr-Nd isotope geochemistry, and igneous and detrital zircon geochronology are consistent with global Paleozoic S-type magmatism along the margins of Gondwana, which may be explained by multiple or a single peri-Gondwanan silicic Large Igneous Province.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"927 ","pages":"Article 231135"},"PeriodicalIF":2.6,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146778216","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}
Pub Date : 2026-04-10Epub Date: 2026-02-18DOI: 10.1016/j.tecto.2026.231127
Takato Takemura , David Healy
Understanding stress-dependent permeability in cracked rocks is crucial for predicting fluid migration in the subsurface subjected to stress and in controlled laboratory experiments. In Oda's permeability tensor, the parameter related to connectivity is represented solely by the fraction of geometrically connected cracks, and neither tortuosity nor bottleneck effects, which are strongly influenced by crack closure, particularly under anisotropic stress, are taken into account. We propose a new crack network parameter, , in tensor form, which is defined to incorporate tortuosity and bottleneck effects. By integrating this parameter into the permeability tensor, fluid flow through crack networks under anisotropic stress conditions can be evaluated. Numerical simulations were performed using idealised three mutually orthogonal crack-set models under hydrostatic, triaxial, and polyaxial stress conditions, with varying crack densities and degrees of anisotropy. In addition, we then compared and validated the equivalent permeability obtained in this study with the results of flow simulations based on a DFN model. The results show that under low crack density, the closure of cracks normal to the loading axis significantly increases tortuosity and forms bottlenecks. It was also shown that permeability decreases in the direction of the loading axis, even within the elastic regime. Moreover, as failure progresses and crack density increases due to crack development, the flow paths tend to become more linear, thereby reducing the influence of tortuosity on permeability. The proposed tensor successfully reproduces this reduction in permeability along the loading direction, which conventional models cannot explain—for instance, the decrease in permeability observed during the crack closure stage of triaxial compression tests. Furthermore, this study presents a practical procedure for estimating from experimental and observational data, including crack orientation, aperture, and elastic wave velocity measurements. These data are incorporated into , which is formulated as a correction factor within the conventional permeability tensor framework.
{"title":"Anisotropic stress-induced permeability change in cracked rock during the crack closure stage: A tensorial approach incorporating tortuosity and bottlenecks","authors":"Takato Takemura , David Healy","doi":"10.1016/j.tecto.2026.231127","DOIUrl":"10.1016/j.tecto.2026.231127","url":null,"abstract":"<div><div>Understanding stress-dependent permeability in cracked rocks is crucial for predicting fluid migration in the subsurface subjected to stress and in controlled laboratory experiments. In Oda's permeability tensor, the parameter related to connectivity is represented solely by the fraction of geometrically connected cracks<em>,</em> and neither tortuosity nor bottleneck effects, which are strongly influenced by crack closure, particularly under anisotropic stress, are taken into account. We propose a new crack network parameter, <span><math><msub><mi>T</mi><mi>ij</mi></msub></math></span>, in tensor form<em>,</em> which is defined to incorporate tortuosity and bottleneck effects. By integrating this parameter into the permeability tensor, fluid flow through crack networks under anisotropic stress conditions can be evaluated. Numerical simulations were performed using idealised three mutually orthogonal crack-set models under hydrostatic, triaxial, and polyaxial stress conditions, with varying crack densities and degrees of anisotropy. In addition, we then compared and validated the equivalent permeability obtained in this study with the results of flow simulations based on a DFN model. The results show that under low crack density, the closure of cracks normal to the loading axis significantly increases tortuosity and forms bottlenecks. It was also shown that permeability decreases in the direction of the loading axis, even within the elastic regime. Moreover, as failure progresses and crack density increases due to crack development, the flow paths tend to become more linear, thereby reducing the influence of tortuosity on permeability. The proposed tensor <span><math><msub><mi>T</mi><mi>ij</mi></msub></math></span> successfully reproduces this reduction in permeability along the loading direction, which conventional models cannot explain—for instance, the decrease in permeability observed during the crack closure stage of triaxial compression tests. Furthermore, this study presents a practical procedure for estimating <span><math><msub><mi>T</mi><mi>ij</mi></msub></math></span> from experimental and observational data, including crack orientation, aperture, and elastic wave velocity measurements. These data are incorporated into <span><math><msub><mi>T</mi><mi>ij</mi></msub></math></span>, which is formulated as a correction factor within the conventional permeability tensor framework.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"927 ","pages":"Article 231127"},"PeriodicalIF":2.6,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146778218","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}
Pub Date : 2026-04-10Epub Date: 2026-02-22DOI: 10.1016/j.tecto.2026.231138
Minyoung Huh , Hyunseong Kim , Changyeol Lee
The origin of the east-west aligned Ulleung-Dok volcano group in the East/Japan Sea is enigmatic, as its formation cannot be explained by simple rifting or arc volcanism. While the wet plume hypothesis has been proposed, it fails to explain why plumes formed earlier and at a shallower depth beneath this region compared to other intraplate volcanoes in Northeast Asia. This study investigates the hypothesis that localized, short-term heating of the subducting Pacific plate beneath the arc could trigger the early formation of a wet plume beneath the volcano group. We test this mechanism using a series of two-dimensional numerical models that implement the interaction between the excess heating and the hydrous layer of the subducting slab. Model results demonstrate the formation of two distinct wet plumes. A deep plume develops from the stagnant slab at approximately 445 km depth, driven by intrinsic buoyancy. However, a shallow wet plume forms at around 350 km depth only when short-term heating is applied to the slab beneath the arc. Parametric analyses confirm that the formation of this shallow plume is sensitive to the duration and intensity of the short-term heating, as well as the thickness and bound-water content of the hydrous layer. We propose that this shallow plume undergoes dehydration and hydrous melting as it is dragged westward by the subducting plate, with the resulting magma ascending to form the volcano group. This mechanism explains the east-to-west age progression of the Ulleung-Dok volcano group, providing a refined framework for understanding plume-slab interactions in subduction zones.
{"title":"Localized slab heating as a trigger for East Asian Back-arc volcanism","authors":"Minyoung Huh , Hyunseong Kim , Changyeol Lee","doi":"10.1016/j.tecto.2026.231138","DOIUrl":"10.1016/j.tecto.2026.231138","url":null,"abstract":"<div><div>The origin of the east-west aligned Ulleung-Dok volcano group in the East/Japan Sea is enigmatic, as its formation cannot be explained by simple rifting or arc volcanism. While the wet plume hypothesis has been proposed, it fails to explain why plumes formed earlier and at a shallower depth beneath this region compared to other intraplate volcanoes in Northeast Asia. This study investigates the hypothesis that localized, short-term heating of the subducting Pacific plate beneath the arc could trigger the early formation of a wet plume beneath the volcano group. We test this mechanism using a series of two-dimensional numerical models that implement the interaction between the excess heating and the hydrous layer of the subducting slab. Model results demonstrate the formation of two distinct wet plumes. A deep plume develops from the stagnant slab at approximately 445 km depth, driven by intrinsic buoyancy. However, a shallow wet plume forms at around 350 km depth only when short-term heating is applied to the slab beneath the arc. Parametric analyses confirm that the formation of this shallow plume is sensitive to the duration and intensity of the short-term heating, as well as the thickness and bound-water content of the hydrous layer. We propose that this shallow plume undergoes dehydration and hydrous melting as it is dragged westward by the subducting plate, with the resulting magma ascending to form the volcano group. This mechanism explains the east-to-west age progression of the Ulleung-Dok volcano group, providing a refined framework for understanding plume-slab interactions in subduction zones.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"927 ","pages":"Article 231138"},"PeriodicalIF":2.6,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146778214","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}
Pub Date : 2026-04-10Epub Date: 2026-02-19DOI: 10.1016/j.tecto.2026.231136
F. Chacón-Hernández , L. Quintanar-Robles , I. Rodríguez-Rasilla
Induced seismicity in the Mexico Basin (MB) occurs along local fault systems that generally align with the maximum regional stress field (SHR max). This seismicity is also influenced by local induction mechanisms, such as groundwater extraction and volcanic activity. Based on 281 shear wave splitting (SWS) measurements, supported by previous results of focal mechanisms, and stress orientation estimates, we identify irregular spatial and temporal stress patterns, reinforcing the hypothesis of a heterogeneous local stress regime across the region. Previous estimates place SHR max between N40°E and N83°E, consistent with our overall average of fast polarizations of ∼N61.7E°, and the orientation of major continental fault systems. The influence of SHR max is more susceptible in certain structurally areas, disseminated under particular deformation regimes that evolve. Approximately 78.57% of the studied regions, mainly in central and northern sectors, are more prone to experience stress-induced anisotropy and therefore trigger seismic swarms, due to NE-SW and ENE-WSW fault systems aligned with SHR max. Around 50% of the regions also appear to be affected by particular transient local stress fields, some of them also exhibiting effects of structure-induced anisotropy. Spatial constraining reveals both clockwise and counterclockwise rotations of anisotropic alignments, with certain evidence of spatio-temporal deformation, with average fractional difference reaching up to 5.9%. Notably, structural reorientations of ∼2.03°/km and ∼ 8.7°/km are observed in the central and central-western sectors, suggesting the coexistence of inherited features and evolving regional stress regimes.
{"title":"Characterizing stress orientations in the Mexico Basin: A crustal anisotropy perspective","authors":"F. Chacón-Hernández , L. Quintanar-Robles , I. Rodríguez-Rasilla","doi":"10.1016/j.tecto.2026.231136","DOIUrl":"10.1016/j.tecto.2026.231136","url":null,"abstract":"<div><div>Induced seismicity in the Mexico Basin (MB) occurs along local fault systems that generally align with the maximum regional stress field (S<sub>HR max</sub>). This seismicity is also influenced by local induction mechanisms, such as groundwater extraction and volcanic activity. Based on 281 shear wave splitting (SWS) measurements, supported by previous results of focal mechanisms, and stress orientation estimates, we identify irregular spatial and temporal stress patterns, reinforcing the hypothesis of a heterogeneous local stress regime across the region. Previous estimates place S<sub>HR max</sub> between N40°E and N83°E, consistent with our overall average of fast polarizations of ∼N61.7E°, and the orientation of major continental fault systems. The influence of S<sub>HR max</sub> is more susceptible in certain structurally areas, disseminated under particular deformation regimes that evolve. Approximately 78.57% of the studied regions, mainly in central and northern sectors, are more prone to experience stress-induced anisotropy and therefore trigger seismic swarms, due to NE-SW and ENE-WSW fault systems aligned with S<sub>HR max</sub>. Around 50% of the regions also appear to be affected by particular transient local stress fields, some of them also exhibiting effects of structure-induced anisotropy. Spatial constraining reveals both clockwise and counterclockwise rotations of anisotropic alignments, with certain evidence of spatio-temporal deformation, with average fractional difference reaching up to 5.9%. Notably, structural reorientations of ∼2.03°/km and ∼ 8.7°/km are observed in the central and central-western sectors, suggesting the coexistence of inherited features and evolving regional stress regimes.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"927 ","pages":"Article 231136"},"PeriodicalIF":2.6,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146778215","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}
Pub Date : 2026-04-10Epub Date: 2026-02-26DOI: 10.1016/j.tecto.2026.231142
Ayaka Tagami , Tomomi Okada , Martha K. Savage , Calum J. Chamberlain , Francesca Ghisetti , Richard Sibson , Kazuya Tateiwa , Miu Matsuno , Satoshi Matsumoto , Yuta Kawamura , Yoshihisa Iio , Tadashi Sato , Satoshi Hirahara , Shuutoku Kimura , Stephen Bannister , John Ristau
The Alpine Fault is a major transpressive right-lateral fault at the intracontinental plate boundary between the Australian and Pacific Plates. Inversion tectonics are inferred to affect a sizable proportion of the active faults in the crust of the Australian Plate, west of the Alpine Fault. However, the relationship between seismic activity and active faulting in this region remains poorly understood. This study presents new data to estimate the stress tensor in the northern South Island and to assess whether historical and recent earthquakes occurred on faults that were favorably oriented to slip. The estimated stress field in the northwestern region of the South Island favors reverse faulting, with dominant N-S faults dipping approximately 30°–60° and being the most favorably oriented for the slip. Both compressionally reactivated normal faults and newly developed reverse faults were found to be favorably oriented to slip under the current stress regime. In contrast, the estimated stress field in the northeastern part of the South Island favors strike-slip faulting, with NE-SW faults dipping approximately 75°–90°, which is the most favorable orientation for slip. Therefore, faults in the Australian and Pacific crusts have the most favorable geometry for being seismically reactivated in the current stress field. However, suboptimal fault clusters were identified west of the Alpine Fault. A previous study observed elevated Vp/Vs ratios extending continuously from the top of the subducting Pacific Plate into the crust in the northwestern South Island, suggesting that crustal overpressured fluid migration may have locally triggered fault activity.
{"title":"Fault activity and stress field of shallow intraplate earthquakes in northern South Island, New Zealand","authors":"Ayaka Tagami , Tomomi Okada , Martha K. Savage , Calum J. Chamberlain , Francesca Ghisetti , Richard Sibson , Kazuya Tateiwa , Miu Matsuno , Satoshi Matsumoto , Yuta Kawamura , Yoshihisa Iio , Tadashi Sato , Satoshi Hirahara , Shuutoku Kimura , Stephen Bannister , John Ristau","doi":"10.1016/j.tecto.2026.231142","DOIUrl":"10.1016/j.tecto.2026.231142","url":null,"abstract":"<div><div>The Alpine Fault is a major transpressive right-lateral fault at the intracontinental plate boundary between the Australian and Pacific Plates. Inversion tectonics are inferred to affect a sizable proportion of the active faults in the crust of the Australian Plate, west of the Alpine Fault. However, the relationship between seismic activity and active faulting in this region remains poorly understood. This study presents new data to estimate the stress tensor in the northern South Island and to assess whether historical and recent earthquakes occurred on faults that were favorably oriented to slip. The estimated stress field in the northwestern region of the South Island favors reverse faulting, with dominant N-S faults dipping approximately 30°–60° and being the most favorably oriented for the slip. Both compressionally reactivated normal faults and newly developed reverse faults were found to be favorably oriented to slip under the current stress regime. In contrast, the estimated stress field in the northeastern part of the South Island favors strike-slip faulting, with NE-SW faults dipping approximately 75°–90°, which is the most favorable orientation for slip. Therefore, faults in the Australian and Pacific crusts have the most favorable geometry for being seismically reactivated in the current stress field. However, suboptimal fault clusters were identified west of the Alpine Fault. A previous study observed elevated Vp/Vs ratios extending continuously from the top of the subducting Pacific Plate into the crust in the northwestern South Island, suggesting that crustal overpressured fluid migration may have locally triggered fault activity.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"927 ","pages":"Article 231142"},"PeriodicalIF":2.6,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147334700","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}
Pub Date : 2026-03-26Epub Date: 2026-02-03DOI: 10.1016/j.tecto.2026.231112
Mohamed Sabri Arfaoui , Mohamed Gharbi
The Middle Mejerda basins of northwestern Tunisia provide a key setting for investigating post-collisional extensional deformation within an active orogenic wedge. This study integrates detailed geological mapping, structural cross-sections, 2D seismic reflection profiles, gravity data, and a new structural map to characterize the geometry, tectonic style, and polyphase evolution of the region. The structural framework comprises four interconnected sub-basins bounded by NE-SW, E-W, and NW-SE fault systems. Despite local variations, all sub-basins record alternating episodes of shortening and extension, expressed by local thrusts, salt-related structures, and regional low-angle detachments and listric normal faults. These extensional systems exerted a first-order control on Neogene sedimentation patterns. The transition from marine to continental deposition reflects a progressive shift from foreland basin development to post-orogenic collapse. Four major unconformities (U1-U4) record successive deformation phases associated with continuous Paleogene-Neogene plate convergence. The integrated structural model highlights the dynamic coupling between fold-and-thrust propagation and gravitational collapse, likely linked to lithospheric delamination and underplating beneath northern Tunisia. These findings clarify the structural architecture of the Middle Mejerda domain and indicate that deformation partitioning between thick- and thin-skinned tectonics played a central role in shaping syn-convergent extensional basins along the southern margin of the Western Mediterranean.
{"title":"Syn-convergent extension and deformation coupling in the Middle Mejerda basins (NW-Tunisia): Insights into polyphase evolution within the Tunisian orogenic wedge","authors":"Mohamed Sabri Arfaoui , Mohamed Gharbi","doi":"10.1016/j.tecto.2026.231112","DOIUrl":"10.1016/j.tecto.2026.231112","url":null,"abstract":"<div><div>The Middle Mejerda basins of northwestern Tunisia provide a key setting for investigating post-collisional extensional deformation within an active orogenic wedge. This study integrates detailed geological mapping, structural cross-sections, 2D seismic reflection profiles, gravity data, and a new structural map to characterize the geometry, tectonic style, and polyphase evolution of the region. The structural framework comprises four interconnected sub-basins bounded by NE-SW, E-W, and NW-SE fault systems. Despite local variations, all sub-basins record alternating episodes of shortening and extension, expressed by local thrusts, salt-related structures, and regional low-angle detachments and listric normal faults. These extensional systems exerted a first-order control on Neogene sedimentation patterns. The transition from marine to continental deposition reflects a progressive shift from foreland basin development to post-orogenic collapse. Four major unconformities (U1-U4) record successive deformation phases associated with continuous Paleogene-Neogene plate convergence. The integrated structural model highlights the dynamic coupling between fold-and-thrust propagation and gravitational collapse, likely linked to lithospheric delamination and underplating beneath northern Tunisia. These findings clarify the structural architecture of the Middle Mejerda domain and indicate that deformation partitioning between thick- and thin-skinned tectonics played a central role in shaping <em>syn</em>-convergent extensional basins along the southern margin of the Western Mediterranean.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"926 ","pages":"Article 231112"},"PeriodicalIF":2.6,"publicationDate":"2026-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110627","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}
Pub Date : 2026-03-26Epub Date: 2026-02-02DOI: 10.1016/j.tecto.2026.231111
Xiubo Wang
The West Pacific subduction zone is a convergence zone marked by significant stress changes and active seismicity due to complex plate tectonics. However, debate continues over the region's stress states. Here, I integrate 4074 Centroid Moment Tensor (CMT) solutions using a robust summation approach, enabling systematic quantification of strain rate partitioning and deformation velocities along the Pacific subduction zone. Through a high-resolution tessellation scheme that divides the region into 37 kinematic domains based on slab geometry (boundary morphology, dip variations), focal mechanisms, and spatial seismicity clustering, I have resolved previously unrecognized strain rate gradients across the outer rise-forearc-backarc continuum, with three key findings: First, depth-dependent slip partitioning with trench-parallel normal faulting dominating the outer rise (0–30 km), transitional strike-slip regimes in the shallow mantle wedge (30–100 km), and trench-perpendicular reverse faulting along the deep plate interface (>100 km). Second, distinct deformation velocity clusters correlate with slab bending stresses at the Kuril-Japan transition zone and triple junction interactions near the Sagami Trough. Third, first-order control of subducting plate curvature on strain localization, where concave trench segments exhibit higher strain rates than convex counterparts due to strong interplate coupling. This approach helps fill observational gaps and provides long-term deformation data for seismic hazard assessment in tectonically active but poorly monitored regions. As a result, the upper slab boundary morphology, geometry, and convergence rate primarily determine the distinct strain rates and deformation velocity patterns, providing valuable insights into long-term stress assessment and earthquake generation in the West Pacific subduction zone.
{"title":"Significant stress variations in the West Pacific subduction zone derived from the summations of moment tensors of seismic events","authors":"Xiubo Wang","doi":"10.1016/j.tecto.2026.231111","DOIUrl":"10.1016/j.tecto.2026.231111","url":null,"abstract":"<div><div>The West Pacific subduction zone is a convergence zone marked by significant stress changes and active seismicity due to complex plate tectonics. However, debate continues over the region's stress states. Here, I integrate 4074 Centroid Moment Tensor (CMT) solutions using a robust summation approach, enabling systematic quantification of strain rate partitioning and deformation velocities along the Pacific subduction zone. Through a high-resolution tessellation scheme that divides the region into 37 kinematic domains based on slab geometry (boundary morphology, dip variations), focal mechanisms, and spatial seismicity clustering, I have resolved previously unrecognized strain rate gradients across the outer rise-forearc-backarc continuum, with three key findings: First, depth-dependent slip partitioning with trench-parallel normal faulting dominating the outer rise (0–30 km), transitional strike-slip regimes in the shallow mantle wedge (30–100 km), and trench-perpendicular reverse faulting along the deep plate interface (>100 km). Second, distinct deformation velocity clusters correlate with slab bending stresses at the Kuril-Japan transition zone and triple junction interactions near the Sagami Trough. Third, first-order control of subducting plate curvature on strain localization, where concave trench segments exhibit higher strain rates than convex counterparts due to strong interplate coupling. This approach helps fill observational gaps and provides long-term deformation data for seismic hazard assessment in tectonically active but poorly monitored regions. As a result, the upper slab boundary morphology, geometry, and convergence rate primarily determine the distinct strain rates and deformation velocity patterns, providing valuable insights into long-term stress assessment and earthquake generation in the West Pacific subduction zone.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"926 ","pages":"Article 231111"},"PeriodicalIF":2.6,"publicationDate":"2026-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110666","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}
Pub Date : 2026-03-26Epub Date: 2026-02-03DOI: 10.1016/j.tecto.2026.231115
Lepolt Linkimer, Ivonne G. Arroyo
The interaction among the Cocos, Nazca, and Panama plates at the Panama Triple Junction (PTJ) generates diverse seismic sources that remain poorly characterized. Using data from the National Seismological Network of Costa Rica and the Chirinet network of Panama, we analyzed four recent earthquake sequences (Mw 5.6–6.2, 2019–2021) near the Burica Peninsula and relocated 32 significant events (Mw 5.6–6.7) that occurred between 2000 and 2025. The results reveal: (1) right-lateral strike-slip faulting along the Panama and Balboa fracture zones; (2) right-lateral faulting on their inland projections, including the 2019 Mw 6.0 Canoas Fault earthquake; (3) reverse faulting during the 2008 (Mw 5.6) and 2020 (Mw 5.6) North Burica sequences, associated with the Media Fault Zone of the upper Panama Plate; (4) left-lateral strike-slip faulting within the subducting Cocos Plate, where at least five Mw 5.8–6.5 events occurred between 2002 and 2019; and (5) a seismogenic Cocos–Panama interplate zone extending southeast of the Burica Peninsula. We further reinterpret the 1934 Ms. 7.6 Armuelles tsunamigenic earthquake as a large megathrust rupture on this interplate boundary. Together, these findings refine the geometry of the seismic sources near the PTJ improving our understanding of the tectonic processes shaping the region.
{"title":"Seismotectonics of the Panama Triple Junction region revealed by recent seismicity","authors":"Lepolt Linkimer, Ivonne G. Arroyo","doi":"10.1016/j.tecto.2026.231115","DOIUrl":"10.1016/j.tecto.2026.231115","url":null,"abstract":"<div><div>The interaction among the Cocos, Nazca, and Panama plates at the Panama Triple Junction (PTJ) generates diverse seismic sources that remain poorly characterized. Using data from the National Seismological Network of Costa Rica and the Chirinet network of Panama, we analyzed four recent earthquake sequences (Mw 5.6–6.2, 2019–2021) near the Burica Peninsula and relocated 32 significant events (Mw 5.6–6.7) that occurred between 2000 and 2025. The results reveal: (1) right-lateral strike-slip faulting along the Panama and Balboa fracture zones; (2) right-lateral faulting on their inland projections, including the 2019 Mw 6.0 Canoas Fault earthquake; (3) reverse faulting during the 2008 (Mw 5.6) and 2020 (Mw 5.6) North Burica sequences, associated with the Media Fault Zone of the upper Panama Plate; (4) left-lateral strike-slip faulting within the subducting Cocos Plate, where at least five Mw 5.8–6.5 events occurred between 2002 and 2019; and (5) a seismogenic Cocos–Panama interplate zone extending southeast of the Burica Peninsula. We further reinterpret the 1934 Ms. 7.6 Armuelles tsunamigenic earthquake as a large megathrust rupture on this interplate boundary. Together, these findings refine the geometry of the seismic sources near the PTJ improving our understanding of the tectonic processes shaping the region.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"926 ","pages":"Article 231115"},"PeriodicalIF":2.6,"publicationDate":"2026-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110629","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}
Pub Date : 2026-03-26Epub Date: 2026-02-03DOI: 10.1016/j.tecto.2026.231114
C. Araque-Pérez , D. Stich , T. Teixido , E. Carmona , J. Morales , F. Mancilla
A detailed seismic imaging profile of the subsurface beneath the Granada Basin (southern Spain) has been generated using P-wave seismic interferometry applied to local microseismicity. The analysis, conducted along a 44 km long, SW–NE trending transect, used 117 well-located earthquakes (12–17 km depth) recorded by only three local stations between 1984 and 2024. Our imaging methodology applies Common Interferometry Points (CIPs), a geometric construction that approximates the stationary phase points for impulsive seismic sources. CIPs provide a robust spatial organization of the interferometric traces, enabling improved stacking, enhanced reflector continuity, and extensive subsurface illumination despite the sparse station coverage. The resulting seismic section reveals the complex crustal architecture in the central part of the basin, including a mid-crustal reflector at 10–15 km depth. This low-angle structure is interpreted as being part of the basal detachment of the basin, decoupling the brittle upper crust from the ductile part. The detachment roots major normal faults that generate horst-and-graben structures within the basin. Integration with four decades of instrumental seismicity supports this structural interpretation and demonstrates the potential of the method to recover deep crustal structure in tectonically active and logistically challenging regions.
{"title":"P-wave seismic interferometric profile within the Granada Basin (Southern-Spain)","authors":"C. Araque-Pérez , D. Stich , T. Teixido , E. Carmona , J. Morales , F. Mancilla","doi":"10.1016/j.tecto.2026.231114","DOIUrl":"10.1016/j.tecto.2026.231114","url":null,"abstract":"<div><div>A detailed seismic imaging profile of the subsurface beneath the Granada Basin (southern Spain) has been generated using P-wave seismic interferometry applied to local microseismicity. The analysis, conducted along a 44 km long, SW–NE trending transect, used 117 well-located earthquakes (12–17 km depth) recorded by only three local stations between 1984 and 2024. Our imaging methodology applies Common Interferometry Points (CIPs), a geometric construction that approximates the stationary phase points for impulsive seismic sources. CIPs provide a robust spatial organization of the interferometric traces, enabling improved stacking, enhanced reflector continuity, and extensive subsurface illumination despite the sparse station coverage. The resulting seismic section reveals the complex crustal architecture in the central part of the basin, including a mid-crustal reflector at 10–15 km depth. This low-angle structure is interpreted as being part of the basal detachment of the basin, decoupling the brittle upper crust from the ductile part. The detachment roots major normal faults that generate <em>horst</em>-and-<em>graben</em> structures within the basin. Integration with four decades of instrumental seismicity supports this structural interpretation and demonstrates the potential of the method to recover deep crustal structure in tectonically active and logistically challenging regions.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"926 ","pages":"Article 231114"},"PeriodicalIF":2.6,"publicationDate":"2026-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110628","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}
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